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- Mac Slow Performance
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- Docker For Mac Slow Ext4 Partition Usb
- Docker For Mac Slow Ext4 Partition Restore
Welcome to Docker Desktop! The Docker Desktop for Mac user manual provides information on how to configure and manage your Docker Desktop settings.
Commands in older versions of Docker e.g. 1.13.x (run as root not sudo): # Delete 'exited' containers docker rm -v $(docker ps -a -q -f status=exited) # Delete 'dangling' images (If there are no images you will get a docker: 'rmi' requires a minimum of 1 argument) docker rmi $(docker images -f 'dangling=true' -q) # Delete 'dangling' volumes (If there are no images you will get a docker. Because of that, Docker runs on Mac OS slowly. You are not able to run the Docker on Mac OS like on Linux. If I need to give some instances about real use-cases. I have the same machine. So, I use Symfony 4 on Docker v18 on Mac OS Mojave. This is my Symfony total execution time on Docker. Docker For Mac Slow Ext4 Partition Steam For Mac Review Gintama Season 2 Sub Indo Download Allahuma Shali Wash Watch Resident Evil 4 Online Pdf2jpg Reviews Of Bio Snazio Dtvpvr S Usb2 Driver For Mac Usb Vid 090c Pid 1000 Rev 1000 Review Windows Installer Kb893803 V2 X64 Or X86.
Because of that, Docker runs on Mac OS slowly. You are not able to run the Docker on Mac OS like on Linux. If I need to give some instances about real use-cases. I have the same machine. So, I use Symfony 4 on Docker v18 on Mac OS Mojave. This is my Symfony total execution time on Docker. Create and work on an ext4 filesystem image inside of macOS using Docker for Mac. Use this method if you aren't using external USB drives and/or don't want to install a fat VM like VirtualBox. Follow the steps outlined on Docker's website. Download Docker for Mac directly.
For information about Docker Desktop download, system requirements, and installation instructions, see Install Docker Desktop.
Preferences
The Docker Preferences menu allows you to configure your Docker settings such as installation, updates, version channels, Docker Hub login,and more.
Choose the Docker menu > Preferences from themenu bar and configure the runtime options described below.
General
On the General tab, you can configure when to start and update Docker:
- Start Docker Desktop when you log in: Automatically starts Docker Desktop when you open your session.
- Include VM in Time Machine backups: Select this option to back up the Docker Desktop virtual machine. This option is disabled by default.
- Securely store Docker logins in macOS keychain: Docker Desktop stores your Docker login credentials in macOS keychain by default.
- Send usage statistics: Docker Desktop sends diagnostics, crash reports, and usage data. This information helps Docker improve and troubleshoot the application. Clear the check box to opt out.
Resources
The Resources tab allows you to configure CPU, memory, disk, proxies, network, and other resources.
Advanced
On the Advanced tab, you can limit resources available to Docker.
Advanced settings are:
CPUs: By default, Docker Desktop is set to use half the number of processorsavailable on the host machine. To increase processing power, set this to ahigher number; to decrease, lower the number.
Memory: By default, Docker Desktop is set to use
2
GB runtime memory,allocated from the total available memory on your Mac. To increase the RAM, set this to a higher number. To decrease it, lower the number.Swap: Configure swap file size as needed. The default is 1 GB.
Disk image size: Specify the size of the disk image.
Disk image location: Specify the location of the Linux volume where containers and images are stored.
You can also move the disk image to a different location. If you attempt to move a disk image to a location that already has one, you get a prompt asking if you want to use the existing image or replace it.
File sharing
Use File sharing to allow local directories on the Mac to be shared with Linux containers.This is especially useful forediting source code in an IDE on the host while running and testing the code in a container.By default the
/Users
, /Volume
, /private
, /tmp
and /var/folders
directory are shared. If your project is outside this directory then it must be addedto the list. Otherwise you may get Mounts denied
or cannot start service
errors at runtime.File share settings are:
- Add a Directory: Click
+
and navigate to the directory you want to add. - Apply & Restart makes the directory available to containers using Docker’sbind mount (
-v
) feature.
Tips on shared folders, permissions, and volume mounts
- Shared folders are designed to allow application code to be edited on the host while being executed in containers. For non-code items such as cache directories or databases, the performance will be much better if they are stored in the Linux VM, using a data volume (named volume) or data container.
- By default, Mac file systems are case-insensitive while Linux is case-sensitive. On Linux, it is possible to create 2 separate files:
test
andTest
, while on Mac these filenames would actually refer to the same underlying file. This can lead to problems where an app works correctly on a Mac (where the file contents are shared) but fails when run in Linux in production (where the file contents are distinct). To avoid this, Docker Desktop insists that all shared files are accessed as their original case. Therefore, if a file is created calledtest
, it must be opened astest
. Attempts to openTest
will fail with the errorNo such file or directory
. Similarly, once a file calledtest
is created, attempts to create a second file calledTest
will fail. For more information, see Volume mounting requires file sharing for any project directories outside of/Users
.)
Proxies
Docker Desktop detects HTTP/HTTPS Proxy Settings from macOS and automaticallypropagates these to Docker. For example, if you set yourproxy settings to
http://proxy.example.com
, Docker uses this proxy whenpulling containers.Your proxy settings, however, will not be propagated into the containers you start.If you wish to set the proxy settings for your containers, you need to defineenvironment variables for them, just like you would do on Linux, for example:
For more information on setting environment variables for running containers,see Set environment variables.
Network
You can configure Docker Desktop networking to work on a virtual private network (VPN). The beginners guide crack. Specify a network address translation (NAT) prefix and subnet mask to enable Internet connectivity.
Docker Engine
![Ext4 partition type Ext4 partition type](/uploads/1/2/6/3/126327887/245556003.png)
The Docker Engine page allows you to configure the Docker daemon to determine how your containers run.
Type a JSON configuration file in the box to configure the daemon settings. For a full list of options, see the Docker Enginedockerd commandline reference.
Click Apply & Restart to save your settings and restart Docker Desktop.
Command Line
On the Command Line page, you can specify whether or not to enable experimental features.
Experimental features provide early access to future product functionality.These features are intended for testing and feedback only as they may changebetween releases without warning or can be removed entirely from a futurerelease. Experimental features must not be used in production environments.Docker does not offer support for experimental features.
To enable experimental features in the Docker CLI, edit the
config.json
file and set experimental
to enabled.Hellpoint for mac. Description For technical reasons the Mac version will be available slightly later. Hellpoint is a dark and challenging action RPG set in a heavily atmospheric sci-fi universe where the line between science and occultism is blurred. Once a pinnacle of human achievement, the Irid Novo space station has fallen. Hellpoint Mac Game Free Download. Hellpoint MacOSX Free Download. Hellpoint: The Irid Novo space station, the pinnacle of human success, crashed once. Their ruins are now awash with violent inter-dimensional beings who act as puppets of the evil Cosmic Gods. Hellpoint is a dark and challenging action RPG set in a heavily atmospheric sci-fi universe where the line between science and occultism is blurred. Once a pinnacle of human achievement, the Irid Novo space station has fallen. Its ruins are now overrun by cruel interdimensional entities acting as puppets of the malevolent Cosmic Gods.
To enable experimental features from the Docker Desktop menu, clickSettings (Preferences on macOS) > Command Line and then turn onthe Enable experimental features toggle. Click Apply & Restart.
For a list of current experimental features in the Docker CLI, see Docker CLI Experimental features.
You can toggle the experimental features on and off in Docker Desktop. If you toggle the experimental features off, Docker Desktop uses the current generally available release of Docker Engine.
You can see whether you are running experimental mode at the command line. If
Experimental
is true
, then Docker is running in experimental mode, as shownhere. (If false
, Experimental mode is off.)Kubernetes
Docker Desktop includes a standalone Kubernetes server that runs on your Mac, sothat you can test deploying your Docker workloads on Kubernetes.
The Kubernetes client command,
kubectl
, is included and configured to connectto the local Kubernetes server. If you have kubectl
already installed andpointing to some other environment, such as minikube
or a GKE cluster, be sureto change context so that kubectl
is pointing to docker-desktop
:If you installed
kubectl
with Homebrew, or by some other method, andexperience conflicts, remove /usr/local/bin/kubectl
.- To enable Kubernetes support and install a standalone instance of Kubernetesrunning as a Docker container, select Enable Kubernetes. To set Kubernetes as thedefault orchestrator, select Deploy Docker Stacks to Kubernetes by default.Click Apply & Restart to save the settings. This instantiates images required to run the Kubernetes server as containers, and installs the
/usr/local/bin/kubectl
command on your Mac.When Kubernetes is enabled and running, an additional status bar item displaysat the bottom right of the Docker Desktop Settings dialog.The status of Kubernetes shows in the Docker menu and the context points todocker-desktop
. - By default, Kubernetes containers are hidden from commands like
dockerservice ls
, because managing them manually is not supported. To make themvisible, select Show system containers (advanced) and click Apply andRestart. Most users do not need this option. - To disable Kubernetes support at any time, clear the Enable Kubernetes check box. TheKubernetes containers are stopped and removed, and the
/usr/local/bin/kubectl
command is removed.For more about using the Kubernetes integration with Docker Desktop, seeDeploy on Kubernetes.
Reset
Reset and Restart options
On Docker Desktop Mac, the Restart Docker Desktop, Reset to factory defaults, and other reset options are available from the Troubleshoot menu.
For information about the reset options, see Logs and Troubleshooting.
Dashboard
The Docker Desktop Dashboard enables you to interact with containers and applications and manage the lifecycle of your applications directly from your machine. The Dashboard UI shows all running, stopped, and started containers with their state. It provides an intuitive interface to perform common actions to inspect and manage containers and existing Docker Compose applications. For more information, see Docker Desktop Dashboard.
Add TLS certificates
You can add trusted Certificate Authorities (CAs) (used to verify registryserver certificates) and client certificates (used to authenticate toregistries) to your Docker daemon.
Add custom CA certificates (server side)
All trusted CAs (root or intermediate) are supported. Docker Desktop creates acertificate bundle of all user-trusted CAs based on the Mac Keychain, andappends it to Moby trusted certificates. So if an enterprise SSL certificate istrusted by the user on the host, it is trusted by Docker Desktop.
To manually add a custom, self-signed certificate, start by adding thecertificate to the macOS keychain, which is picked up by Docker Desktop. Here isan example:
Or, if you prefer to add the certificate to your own local keychain only (ratherthan for all users), run this command instead:
See also, Directory structures forcertificates.
Note: You need to restart Docker Desktop after making any changes to thekeychain or to the
~/.docker/certs.d
directory in order for the changes totake effect.For a complete explanation of how to do this, see the blog post AddingSelf-signed Registry Certs to Docker & Docker Desktop forMac.
Add client certificates
You can put your client certificates in
~/.docker/certs.d/<MyRegistry>:<Port>/client.cert
and~/.docker/certs.d/<MyRegistry>:<Port>/client.key
.When the Docker Desktop application starts, it copies the
~/.docker/certs.d
folder on your Mac to the /etc/docker/certs.d
directory on Moby (the DockerDesktop xhyve
virtual machine).- You need to restart Docker Desktop after making any changes to the keychainor to the
~/.docker/certs.d
directory in order for the changes to takeeffect. - The registry cannot be listed as an insecure registry (see DockerEngine. Docker Desktop ignores certificates listedunder insecure registries, and does not send client certificates. Commandslike
docker run
that attempt to pull from the registry produce errormessages on the command line, as well as on the registry.
Directory structures for certificates
If you have this directory structure, you do not need to manually add the CAcertificate to your Mac OS system login:
The following further illustrates and explains a configuration with customcertificates:
You can also have this directory structure, as long as the CA certificate isalso in your keychain.
To learn more about how to install a CA root certificate for the registry andhow to set the client TLS certificate for verification, seeVerify repository client with certificatesin the Docker Engine topics.
Install shell completion
Docker Desktop comes with scripts to enable completion for the
docker
and docker-compose
commands. The completion scripts may befound inside Docker.app
, in the Contents/Resources/etc/
directory and can beinstalled both in Bash and Zsh.Bash
Bash has built-in support forcompletion To activate completion for Docker commands, these files need to becopied or symlinked to your
bash_completion.d/
directory. For example, if youinstalled bash via Homebrew:Add the following to your
~/.bash_profile
:OR
Zsh
In Zsh, the completionsystemtakes care of things. To activate completion for Docker commands,these files need to be copied or symlinked to your Zsh
site-functions/
directory. For example, if you installed Zsh via Homebrew:Fish-Shell
Fish-shell also supports tab completion completionsystem. To activate completion for Docker commands,these files need to be copied or symlinked to your Fish-shell
completions/
directory.Create the
completions
directory:Now add fish completions from docker.
Give feedback and get help
To get help from the community, review current user topics, join or start adiscussion, log on to our Docker Desktop for Macforum.
To report bugs or problems, log on to Docker Desktop for Mac issues onGitHub,where you can review community reported issues, and file new ones. SeeLogs and Troubleshooting for more details.
For information about providing feedback on the documentation or update it yourself, see Contribute to documentation.
Docker Hub
Select Sign in /Create Docker ID from the Docker Desktop menu to access your Docker Hub account. Once logged in, you can access your Docker Hub repositories and organizations directly from the Docker Desktop menu.
For more information, refer to the following Docker Hub topics:
Two-factor authentication
Mac Slow Performance
Docker Desktop enables you to sign into Docker Hub using two-factor authentication. Two-factor authentication provides an extra layer of security when accessing your Docker Hub account.
You must enable two-factor authentication in Docker Hub before signing into your Docker Hub account through Docker Desktop. For instructions, see Enable two-factor authentication for Docker Hub.
After you have enabled two-factor authentication: Vhdl code for 3x8 decoder.
- Go to the Docker Desktop menu and then select Sign in / Create Docker ID.
- Enter your Docker ID and password and click Sign in.
- After you have successfully signed in, Docker Desktop prompts you to enter the authentication code. Enter the six-digit code from your phone and then click Verify.
After you have successfully authenticated, you can access your organizations and repositories directly from the Docker Desktop menu.
Where to go next
- Try out the walkthrough at Get Started.
- Dig in deeper with Docker Labs examplewalkthroughs and source code.
- For a summary of Docker command line interface (CLI) commands, seeDocker CLI Reference Guide.
- Check out the blog post, What’s New in Docker 17.06 Community Edition(CE).
Device Mapper is a kernel-based framework that underpins many advancedvolume management technologies on Linux. Docker’s
devicemapper
storage driverleverages the thin provisioning and snapshotting capabilities of this frameworkfor image and container management. This article refers to the Device Mapperstorage driver as devicemapper
, and the kernel framework as Device Mapper.For the systems where it is supported,
devicemapper
support is included inthe Linux kernel. However, specific configuration is required to use it withDocker.The
devicemapper
driver uses block devices dedicated to Docker and operates atthe block level, rather than the file level. These devices can be extended byadding physical storage to your Docker host, and they perform better than usinga filesystem at the operating system (OS) level.Prerequisites
This, for example, means that only the boot partition created to install the system appears when the Raspberry MicroSD is installed. So, on this tutorial, I will explain how to mount a Linux partition EXT4, EXT3, EXT2 to Windows 10, 8, 7. Some of the reasons for mounting Linux drives in Windows are: Create dual-boot systems (Windows and Linux). Then, copy all the data from the ext4 partition to the btrfs partition: cp -ax is your. Both readable and writable on any modern Mac or Windows machine (sorry. Usage but also it was terribly slow on my root subvolume where docker uses.
devicemapper
storage driver is a supported storage driver for DockerEE on many OS distribution. See theProduct compatibility matrix for details.devicemapper
is also supported on Docker Engine - Community running on CentOS, Fedora,Ubuntu, or Debian.- Changing the storage driver makes any containers you have alreadycreated inaccessible on the local system. Use
docker save
to save containers,and push existing images to Docker Hub or a private repository, so you donot need to recreate them later.
Configure Docker with the devicemapper
storage driver
Before following these procedures, you must first meet all theprerequisites.
Configure loop-lvm
mode for testing
This configuration is only appropriate for testing. The
loop-lvm
mode makesuse of a ‘loopback’ mechanism that allows files on the local disk to beread from and written to as if they were an actual physical disk or blockdevice.However, the addition of the loopback mechanism, and interaction with the OSfilesystem layer, means that IO operations can be slow and resource-intensive.Use of loopback devices can also introduce race conditions.However, setting up loop-lvm
mode can help identify basic issues (such asmissing user space packages, kernel drivers, etc.) ahead of attempting the morecomplex set up required to enable direct-lvm
mode. loop-lvm
mode shouldtherefore only be used to perform rudimentary testing prior to configuringdirect-lvm
.For production systems, seeConfigure direct-lvm mode for production.
- Stop Docker.
- Edit
/etc/docker/daemon.json
. If it does not yet exist, create it. Assumingthat the file was empty, add the following contents.See all storage options for each storage driver:Docker does not start if thedaemon.json
file contains badly-formed JSON. - Start Docker.
- Verify that the daemon is using the
devicemapper
storage driver. Use thedocker info
command and look forStorage Driver
.
This host is running in
loop-lvm
mode, which is not supported on production systems. This is indicated by the fact that the Data loop file
and a Metadata loop file
are on files under /var/lib/docker/devicemapper
. These are loopback-mounted sparse files. For production systems, see Configure direct-lvm mode for production.Configure direct-lvm mode for production
Production hosts using the
devicemapper
storage driver must use direct-lvm
mode. This mode uses block devices to create the thin pool. This is faster thanusing loopback devices, uses system resources more efficiently, and blockdevices can grow as needed. However, more setup is required than in loop-lvm
mode.After you have satisfied the prerequisites, follow the stepsbelow to configure Docker to use the
devicemapper
storage driver indirect-lvm
mode.Warning: Changing the storage driver makes any containers you have already created inaccessible on the local system. Use
docker save
to save containers, and push existing images to Docker Hub or a private repository, so you do not need to recreate them later.Allow Docker to configure direct-lvm mode
With Docker
17.06
and higher, Docker can manage the block device for you,simplifying configuration of direct-lvm
mode. This is appropriate for fresh Docker setups only. You can only use a single block device. If you need touse multiple block devices, configure direct-lvm modemanually instead. The following newconfiguration options have been added:Option | Description | Required? | Default | Example |
---|---|---|---|---|
dm.directlvm_device | The path to the block device to configure for direct-lvm . | Yes | dm.directlvm_device='/dev/xvdf' | |
dm.thinp_percent | The percentage of space to use for storage from the passed in block device. | No | 95 | dm.thinp_percent=95 |
dm.thinp_metapercent | The percentage of space to use for metadata storage from the passed-in block device. | No | 1 | dm.thinp_metapercent=1 |
dm.thinp_autoextend_threshold | The threshold for when lvm should automatically extend the thin pool as a percentage of the total storage space. | No | 80 | dm.thinp_autoextend_threshold=80 |
dm.thinp_autoextend_percent | The percentage to increase the thin pool by when an autoextend is triggered. | No | 20 | dm.thinp_autoextend_percent=20 |
dm.directlvm_device_force | Whether to format the block device even if a filesystem already exists on it. If set to false and a filesystem is present, an error is logged and the filesystem is left intact. | No | false | dm.directlvm_device_force=true |
Edit the
daemon.json
file and set the appropriate options, then restart Dockerfor the changes to take effect. The following daemon.json
configuration sets all of theoptions in the table above.See all storage options for each storage driver:
Restart Docker for the changes to take effect. Docker invokes the commands toconfigure the block device for you.
Warning: Changing these values after Docker has prepared the block devicefor you is not supported and causes an error.
You still need to perform periodic maintenance tasks.
Configure direct-lvm mode manually
The procedure below creates a logical volume configured as a thin pool touse as backing for the storage pool. It assumes that you have a spare blockdevice at
/dev/xvdf
with enough free space to complete the task. The deviceidentifier and volume sizes may be different in your environment and youshould substitute your own values throughout the procedure. The procedure alsoassumes that the Docker daemon is in the stopped
state.- Identify the block device you want to use. The device is located under
/dev/
(such as/dev/xvdf
) and needs enough free space to store theimages and container layers for the workloads that host runs.A solid state drive is ideal. - Stop Docker.
- Install the following packages:
- RHEL / CentOS:
device-mapper-persistent-data
,lvm2
, and alldependencies - Ubuntu / Debian:
thin-provisioning-tools
,lvm2
, and alldependencies
- Create a physical volume on your block device from step 1, using the
pvcreate
command. Substitute your device name for/dev/xvdf
.Warning: The next few steps are destructive, so be sure that you havespecified the correct device! - Create a
docker
volume group on the same device, using thevgcreate
command. - Create two logical volumes named
thinpool
andthinpoolmeta
using thelvcreate
command. The last parameter specifies the amount of free spaceto allow for automatic expanding of the data or metadata if space runs low,as a temporary stop-gap. These are the recommended values. - Convert the volumes to a thin pool and a storage location for metadata forthe thin pool, using the
lvconvert
command. - Configure autoextension of thin pools via an
lvm
profile. - Specify
thin_pool_autoextend_threshold
andthin_pool_autoextend_percent
values.thin_pool_autoextend_threshold
is the percentage of space used beforelvm
attempts to autoextend the available space (100 = disabled, not recommended).thin_pool_autoextend_percent
is the amount of space to add to the devicewhen automatically extending (0 = disabled).The example below adds 20% more capacity when the disk usage reaches80%.Save the file. - Apply the LVM profile, using the
lvchange
command. - Ensure monitoring of the logical volume is enabled.If the output in the
Monitor
column reports, as above, that the volume isnot monitored
, then monitoring needs to be explicitly enabled. Withoutthis step, automatic extension of the logical volume will not occur,regardless of any settings in the applied profile.Double check that monitoring is now enabled by running thesudo lvs -o+seg_monitor
command a second time. TheMonitor
columnshould now report the logical volume is beingmonitored
. - If you have ever run Docker on this host before, or if
/var/lib/docker/
exists, move it out of the way so that Docker can use the new LVM pool tostore the contents of image and containers.If any of the following steps fail and you need to restore, you can remove/var/lib/docker
and replace it with/var/lib/docker.bk
. - Edit
/etc/docker/daemon.json
and configure the options needed for thedevicemapper
storage driver. If the file was previously empty, it shouldnow contain the following contents: - Start Docker.systemd:service:
- Verify that Docker is using the new configuration using
docker info
.If Docker is configured correctly, theData file
andMetadata file
isblank, and the pool name isdocker-thinpool
. - After you have verified that the configuration is correct, you can remove the
/var/lib/docker.bk
directory which contains the previous configuration.
Manage devicemapper
Monitor the thin pool
Do not rely on LVM auto-extension alone. The volume groupautomatically extends, but the volume can still fill up. You can monitorfree space on the volume using
lvs
or lvs -a
. Consider using a monitoringtool at the OS level, such as Nagios.To view the LVM logs, you can use
journalctl
:If you run into repeated problems with thin pool, you can set the storage option
dm.min_free_space
to a value (representing a percentage) in/etc/docker/daemon.json
. For instance, setting it to 10
ensuresthat operations fail with a warning when the free space is at or near 10%.See thestorage driver options in the Engine daemon reference.Increase capacity on a running device
You can increase the capacity of the pool on a running thin-pool device. This isuseful if the data’s logical volume is full and the volume group is at fullcapacity. The specific procedure depends on whether you are using aloop-lvm thin pool or adirect-lvm thin pool.
Resize a loop-lvm thin pool
The easiest way to resize a
loop-lvm
thin pool is touse the device_tool utility,but you can use operating system utilitiesinstead.Use the device_tool utility
A community-contributed script called
device_tool.go
is available in themoby/mobyGithub repository. You can use this tool to resize a loop-lvm
thin pool,avoiding the long process above. This tool is not guaranteed to work, but youshould only be using loop-lvm
on non-production systems.If you do not want to use
device_tool
, you can resize the thin pool manually instead.- To use the tool, clone the Github repository, change to the
contrib/docker-device-tool
, and follow the instructions in theREADME.md
to compile the tool. - Use the tool. The following example resizes the thin pool to 200GB.
Use operating system utilities
If you do not want to use the device-tool utility,you can resize a
loop-lvm
thin pool manually using the following procedure.In
loop-lvm
mode, a loopback device is used to store the data, and anotherto store the metadata. loop-lvm
mode is only supported for testing, becauseit has significant performance and stability drawbacks.If you are using
loop-lvm
mode, the output of docker info
shows filepaths for Data loop file
and Metadata loop file
:Follow these steps to increase the size of the thin pool. In this example, thethin pool is 100 GB, and is increased to 200 GB.
- List the sizes of the devices.
- Increase the size of the
data
file to 200 G using thetruncate
command,which is used to increase or decrease the size of a file. Note thatdecreasing the size is a destructive operation. - Verify the file size changed.
- The loopback file has changed on disk but not in memory. List the size ofthe loopback device in memory, in GB. Reload it, then list the size again.After the reload, the size is 200 GB.
- Reload the devicemapper thin pool.a. Get the pool name first. The pool name is the first field, delimited by ` :`. This command extracts it.b. Dump the device mapper table for the thin pool.c. Calculate the total sectors of the thin pool using the second field of the output. The number is expressed in 512-k sectors. A 100G file has 209715200 512-k sectors. If you double this number to 200G, you get 419430400 512-k sectors.d. Reload the thin pool with the new sector number, using the following three
dmsetup
commands.
Resize a direct-lvm thin pool
To extend a
direct-lvm
thin pool, you need to first attach a new block deviceto the Docker host, and make note of the name assigned to it by the kernel. Inthis example, the new block device is /dev/xvdg
.Follow this procedure to extend a
direct-lvm
thin pool, substituting yourblock device and other parameters to suit your situation.- Gather information about your volume group.Use the
pvdisplay
command to find the physical block devices currently inuse by your thin pool, and the volume group’s name.In the following steps, substitute your block device or volume group name asappropriate. - Extend the volume group, using the
vgextend
command with theVG Name
from the previous step, and the name of your new block device. - Extend the
docker/thinpool
logical volume. This command uses 100% of thevolume right away, without auto-extend. To extend the metadata thinpoolinstead, usedocker/thinpool_tmeta
. - Verify the new thin pool size using the
Data Space Available
field in theoutput ofdocker info
. If you extended thedocker/thinpool_tmeta
logicalvolume instead, look forMetadata Space Available
.
Activate the devicemapper
after reboot
If you reboot the host and find that the
docker
service failed to start,look for the error, “Non existing device”. You need to re-activate thelogical volumes with this command:Mac Slow Startup
How the devicemapper
storage driver works
Warning: Do not directly manipulate any files or directories within
/var/lib/docker/
. These files and directories are managed by Docker.Use the
lsblk
command to see the devices and their pools, from the operatingsystem’s point of view:Use the
mount
command to see the mount-point Docker is using:When you use
devicemapper
, Docker stores image and layer contents in thethinpool, and exposes them to containers by mounting them undersubdirectories of /var/lib/docker/devicemapper/
.Image and container layers on-disk
The
/var/lib/docker/devicemapper/metadata/
directory contains metadata aboutthe Devicemapper configuration itself and about each image and container layerthat exist. The devicemapper
storage driver uses snapshots, and this metadatainclude information about those snapshots. These files are in JSON format.The
/var/lib/docker/devicemapper/mnt/
directory contains a mount point for each imageand container layer that exists. Image layer mount points are empty, but acontainer’s mount point shows the container’s filesystem as it appears fromwithin the container.Image layering and sharing
The
devicemapper
storage driver uses dedicated block devices rather thanformatted filesystems, and operates on files at the block level for maximumperformance during copy-on-write (CoW) operations.Snapshots
Another feature of
devicemapper
is its use of snapshots (also sometimes calledthin devices or virtual devices), which store the differences introduced ineach layer as very small, lightweight thin pools. Snapshots provide manybenefits:- Layers which are shared in common between containers are only stored on diskonce, unless they are writable. For instance, if you have 10 differentimages which are all based on
alpine
, thealpine
image and all itsparent images are only stored once each on disk. - Snapshots are an implementation of a copy-on-write (CoW) strategy. This meansthat a given file or directory is only copied to the container’s writablelayer when it is modified or deleted by that container.
- Because
devicemapper
operates at the block level, multiple blocks in awritable layer can be modified simultaneously. - Snapshots can be backed up using standard OS-level backup utilities. Justmake a copy of
/var/lib/docker/devicemapper/
.
Devicemapper workflow
When you start Docker with the
devicemapper
storage driver, all objectsrelated to image and container layers are stored in/var/lib/docker/devicemapper/
, which is backed by one or more block-leveldevices, either loopback devices (testing only) or physical disks.- The base device is the lowest-level object. This is the thin pool itself.You can examine it using
docker info
. It contains a filesystem. This basedevice is the starting point for every image and container layer. The basedevice is a Device Mapper implementation detail, rather than a Docker layer. - Metadata about the base device and each image or container layer is stored in
/var/lib/docker/devicemapper/metadata/
in JSON format. These layers arecopy-on-write snapshots, which means that they are empty until they divergefrom their parent layers. - Each container’s writable layer is mounted on a mountpoint in
/var/lib/docker/devicemapper/mnt/
. An empty directory exists for eachread-only image layer and each stopped container.
Each image layer is a snapshot of the layer below it. The lowest layer of eachimage is a snapshot of the base device that exists in the pool. When you run acontainer, it is a snapshot of the image the container is based on. The followingexample shows a Docker host with two running containers. The first is a
ubuntu
container and the second is a busybox
container.How container reads and writes work with devicemapper
![Docker for mac slow ext4 partition restore Docker for mac slow ext4 partition restore](/uploads/1/2/6/3/126327887/801654627.png)
Reading files
With
devicemapper
, reads happen at the block level. The diagram below showsthe high level process for reading a single block (0x44f
) in an examplecontainer.An application makes a read request for block
0x44f
in the container. Becausethe container is a thin snapshot of an image, it doesn’t have the block, but ithas a pointer to the block on the nearest parent image where it does exist, andit reads the block from there. The block now exists in the container’s memory.Writing files
Writing a new file: With the
devicemapper
driver, writing new data to acontainer is accomplished by an allocate-on-demand operation. Each block ofthe new file is allocated in the container’s writable layer and the block iswritten there.Updating an existing file: The relevant block of the file is read from thenearest layer where it exists. When the container writes the file, only themodified blocks are written to the container’s writable layer.
Deleting a file or directory: When you delete a file or directory in acontainer’s writable layer, or when an image layer deletes a file that existsin its parent layer, the
devicemapper
storage driver intercepts further readattempts on that file or directory and responds that the file or directory doesnot exist.Writing and then deleting a file: If a container writes to a file and laterdeletes the file, all of those operations happen in the container’s writablelayer. In that case, if you are using
direct-lvm
, the blocks are freed. If youuse loop-lvm
, the blocks may not be freed. This is another reason not to useloop-lvm
in production.View Ext4 Partition Windows
Device Mapper and Docker performance
allocate-on demand
performance impact:Thedevicemapper
storage driver uses anallocate-on-demand
operation toallocate new blocks from the thin pool into a container’s writable layer.Each block is 64KB, so this is the minimum amount of space that is usedfor a write.- Copy-on-write performance impact: The first time a container modifies aspecific block, that block is written to the container’s writable layer.Because these writes happen at the level of the block rather than the file,performance impact is minimized. However, writing a large number of blocks canstill negatively impact performance, and the
devicemapper
storage driver mayactually perform worse than other storage drivers in this scenario. Forwrite-heavy workloads, you should use data volumes, which bypass the storagedriver completely.
Performance best practices
Keep these things in mind to maximize performance when using the
devicemapper
storage driver.- Use
direct-lvm
: Theloop-lvm
mode is not performant and should neverbe used in production. - Use fast storage: Solid-state drives (SSDs) provide faster reads andwrites than spinning disks.
- Memory usage: the
devicemapper
uses more memory than some other storagedrivers. Each launched container loads one or more copies of its files intomemory, depending on how many blocks of the same file are being modified atthe same time. Due to the memory pressure, thedevicemapper
storage drivermay not be the right choice for certain workloads in high-density use cases. Madness: project nexus soundtrack crack. - Use volumes for write-heavy workloads: Volumes provide the best and mostpredictable performance for write-heavy workloads. This is because they bypassthe storage driver and do not incur any of the potential overheads introducedby thin provisioning and copy-on-write. Volumes have other benefits, such asallowing you to share data among containers and persisting even when norunning container is using them.
- Note: when using
devicemapper
and thejson-file
log driver, the logfiles generated by a container are still stored in Docker’s dataroot directory, by default/var/lib/docker
. If your containers generate lots of log messages, this may lead to increased disk usage or the inability to manage your system dueto a full disk. You can configure a log driver to store your containerlogs externally.
Related Information
container, storage, driver, device mapperCreate and work on an ext4 filesystem image inside of macOS using Docker for Mac. Use this method if you aren't using external USB drives and/or don't want to install a fat VM like VirtualBox.
1. Install Docker
Follow the steps outlined on Docker's website.
Download Docker for Mac directly.
2. Create a working folder
Pick a directory to start in: e.g.
mkdir -p $HOME/ext4fs
3. Run an Ubuntu container
Run the container in privileged mode and mount the directory you just created:
4. Create a raw disk image
Create a blank file and format it as ext4:
Docker For Mac Slow Ext4 Partition Usb
5. Verify the image is mounted
Enter the directory where the image is mounted to see if it formatted correctly:
Docker For Mac Slow Ext4 Partition Restore
6. Profit
When finished, you can unmount the directory (
umount /ext4fs
) and exit the container. Then on your host filesystem you'll have a shiny new raw ext4 image which you can then use other tools to convert to other image types, e.g. VirtualBox, VMWare, etc., using tools like Packer.Note: this method does not mount external drives, as currently USB devices aren't supported in Docker for Mac. You may be able to mount partitions or other disk images, if you copy them into and mount another directory alongside your ext4 filesystem:
You can then use any tools available to Ubuntu to work on other disk images or partitions while inside the container, having full read-write access to your ext4 partition.
Note: your mounted filesystem will not be visible to the host OS, as it's mounted in a loopback inside the container's OS.