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Merge pull request #113 from mbentley/fix-devicemapper-docs 

Fixed jekyll formatting for dm docs; fixed #112
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John Mulhausen 2016-10-06 21:55:35 -07:00 committed by GitHub
parent bdc4a3b934 73fac8acb7
commit 1357a4486d
1 changed files with 153 additions and 151 deletions
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engine/userguide/storagedriver/device-mapper-driver.md
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@ -194,7 +194,7 @@ Storage Driver: devicemapper
Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
Library Version: 1.02.93-RHEL7 (2015-01-28) Library Version: 1.02.93-RHEL7 (2015-01-28)
[...] [...]
``` ```
The output above shows a Docker host running with the `devicemapper` storage The output above shows a Docker host running with the `devicemapper` storage
driver operating in `loop-lvm` mode. This is indicated by the fact that the driver operating in `loop-lvm` mode. This is indicated by the fact that the
@ -223,125 +223,126 @@ assumes that the Docker daemon is in the `stopped` state.
1. Log in to the Docker host you want to configure and stop the Docker daemon. 1. Log in to the Docker host you want to configure and stop the Docker daemon.
2. Install the LVM2 package. 2. Install the LVM2 package.
The LVM2 package includes the userspace toolset that provides logical volume
management facilities on linux. The LVM2 package includes the userspace toolset that provides logical volume
management facilities on linux.
3. Create a physical volume replacing `/dev/xvdf` with your block device. 3. Create a physical volume replacing `/dev/xvdf` with your block device.
```bash ```bash
$ pvcreate /dev/xvdf $ pvcreate /dev/xvdf
``` ```
4. Create a 'docker' volume group. 4. Create a 'docker' volume group.
```bash ```bash
$ vgcreate docker /dev/xvdf $ vgcreate docker /dev/xvdf
``` ```
5. Create a thin pool named `thinpool`. 5. Create a thin pool named `thinpool`.
In this example, the data logical is 95% of the 'docker' volume group size. In this example, the data logical is 95% of the 'docker' volume group size.
Leaving this free space allows for auto expanding of either the data or Leaving this free space allows for auto expanding of either the data or
metadata if space runs low as a temporary stopgap. metadata if space runs low as a temporary stopgap.
```bash ```bash
$ lvcreate --wipesignatures y -n thinpool docker -l 95%VG $ lvcreate --wipesignatures y -n thinpool docker -l 95%VG
$ lvcreate --wipesignatures y -n thinpoolmeta docker -l 1%VG $ lvcreate --wipesignatures y -n thinpoolmeta docker -l 1%VG
``` ```
6. Convert the pool to a thin pool. 6. Convert the pool to a thin pool.
```bash ```bash
$ lvconvert -y --zero n -c 512K --thinpool docker/thinpool --poolmetadata docker/thinpoolmeta $ lvconvert -y --zero n -c 512K --thinpool docker/thinpool --poolmetadata docker/thinpoolmeta
``` ```
7. Configure autoextension of thin pools via an `lvm` profile. 7. Configure autoextension of thin pools via an `lvm` profile.
```bash ```bash
$ vi /etc/lvm/profile/docker-thinpool.profile $ vi /etc/lvm/profile/docker-thinpool.profile
``` ```
8. Specify 'thin_pool_autoextend_threshold' value. 8. Specify `thin_pool_autoextend_threshold` value.
The value should be the percentage of space used before `lvm` attempts The value should be the percentage of space used before `lvm` attempts
to autoextend the available space (100 = disabled). to autoextend the available space (100 = disabled).
``` ```
thin_pool_autoextend_threshold = 80 thin_pool_autoextend_threshold = 80
``` ```
9. Modify the `thin_pool_autoextend_percent` for when thin pool autoextension occurs. 9. Modify the `thin_pool_autoextend_percent` for when thin pool autoextension occurs.
The value's setting is the percentage of space to increase the thin pool (100 = The value's setting is the percentage of space to increase the thin pool (100 =
disabled) disabled)
``` ```
thin_pool_autoextend_percent = 20 thin_pool_autoextend_percent = 20
``` ```
10. Check your work, your `docker-thinpool.profile` file should appear similar to the following: 10. Check your work, your `docker-thinpool.profile` file should appear similar to the following:
An example `/etc/lvm/profile/docker-thinpool.profile` file: An example `/etc/lvm/profile/docker-thinpool.profile` file:
``` ```
activation { activation {
thin_pool_autoextend_threshold=80 thin_pool_autoextend_threshold=80
thin_pool_autoextend_percent=20 thin_pool_autoextend_percent=20
} }
``` ```
11. Apply your new lvm profile 11. Apply your new lvm profile
```bash ```bash
$ lvchange --metadataprofile docker-thinpool docker/thinpool $ lvchange --metadataprofile docker-thinpool docker/thinpool
``` ```
12. Verify the `lv` is monitored. 12. Verify the `lv` is monitored.
```bash ```bash
$ lvs -o+seg_monitor $ lvs -o+seg_monitor
``` ```
13. If the Docker daemon was previously started, clear your graph driver directory. 13. If the Docker daemon was previously started, clear your graph driver directory.
Clearing your graph driver removes any images, containers, and volumes in your Clearing your graph driver removes any images, containers, and volumes in your
Docker installation. Docker installation.
```bash ```bash
$ rm -rf /var/lib/docker/* $ rm -rf /var/lib/docker/*
``` ```
14. Configure the Docker daemon with specific devicemapper options. 14. Configure the Docker daemon with specific devicemapper options.
There are two ways to do this. You can set options on the command line if you start the daemon there: There are two ways to do this. You can set options on the command line if you start the daemon there:
```bash ```bash
--storage-driver=devicemapper --storage-opt=dm.thinpooldev=/dev/mapper/docker-thinpool --storage-opt dm.use_deferred_removal=true --storage-driver=devicemapper --storage-opt=dm.thinpooldev=/dev/mapper/docker-thinpool --storage-opt dm.use_deferred_removal=true
``` ```
You can also set them for startup in the `daemon.json` configuration, for example: You can also set them for startup in the `daemon.json` configuration, for example:
```json ```json
{ {
"storage-driver": "devicemapper", "storage-driver": "devicemapper",
"storage-opts": [ "storage-opts": [
"dm.thinpooldev=/dev/mapper/docker-thinpool", "dm.thinpooldev=/dev/mapper/docker-thinpool",
"dm.use_deferred_removal=true" "dm.use_deferred_removal=true"
] ]
} }
``` ```
15. If using systemd and modifying the daemon configuration via unit or drop-in file, reload systemd to scan for changes. 15. If using systemd and modifying the daemon configuration via unit or drop-in file, reload systemd to scan for changes.
```bash ```bash
$ systemctl daemon-reload $ systemctl daemon-reload
``` ```
16. Start the Docker daemon. 16. Start the Docker daemon.
```bash ```bash
$ systemctl start docker $ systemctl start docker
``` ```
After you start the Docker daemon, ensure you monitor your thin pool and volume After you start the Docker daemon, ensure you monitor your thin pool and volume
group free space. While the volume group will auto-extend, it can still fill group free space. While the volume group will auto-extend, it can still fill
@ -453,79 +454,79 @@ The `Data Space` values show that the pool is 100GB total. This example extends
1. List the sizes of the devices. 1. List the sizes of the devices.
```bash ```bash
$ sudo ls -lh /var/lib/docker/devicemapper/devicemapper/ $ sudo ls -lh /var/lib/docker/devicemapper/devicemapper/
total 1175492 total 1175492
-rw------- 1 root root 100G Mar 30 05:22 data -rw------- 1 root root 100G Mar 30 05:22 data
-rw------- 1 root root 2.0G Mar 31 11:17 metadata -rw------- 1 root root 2.0G Mar 31 11:17 metadata
``` ```
2. Truncate `data` file to the size of the `metadata` file (approximage 200GB). 2. Truncate `data` file to the size of the `metadata` file (approximage 200GB).
```bash ```bash
$ sudo truncate -s 214748364800 /var/lib/docker/devicemapper/devicemapper/data $ sudo truncate -s 214748364800 /var/lib/docker/devicemapper/devicemapper/data
``` ```
3. Verify the file size changed. 3. Verify the file size changed.
```bash ```bash
$ sudo ls -lh /var/lib/docker/devicemapper/devicemapper/ $ sudo ls -lh /var/lib/docker/devicemapper/devicemapper/
total 1.2G total 1.2G
-rw------- 1 root root 200G Apr 14 08:47 data -rw------- 1 root root 200G Apr 14 08:47 data
-rw------- 1 root root 2.0G Apr 19 13:27 metadata -rw------- 1 root root 2.0G Apr 19 13:27 metadata
``` ```
4. Reload data loop device 4. Reload data loop device
```bash ```bash
$ sudo blockdev --getsize64 /dev/loop0 $ sudo blockdev --getsize64 /dev/loop0
107374182400 107374182400
$ sudo losetup -c /dev/loop0 $ sudo losetup -c /dev/loop0
$ sudo blockdev --getsize64 /dev/loop0 $ sudo blockdev --getsize64 /dev/loop0
214748364800 214748364800
``` ```
5. Reload devicemapper thin pool. 5. Reload devicemapper thin pool.
a. Get the pool name first. 1. Get the pool name first.
```bash ```bash
$ sudo dmsetup status | grep pool $ sudo dmsetup status | grep pool
docker-8:1-123141-pool: 0 209715200 thin-pool 91 docker-8:1-123141-pool: 0 209715200 thin-pool 91
422/524288 18338/1638400 - rw discard_passdown queue_if_no_space - 422/524288 18338/1638400 - rw discard_passdown queue_if_no_space -
``` ```
The name is the string before the colon. The name is the string before the colon.
b. Dump the device mapper table first. 2. Dump the device mapper table first.
```bash ```bash
$ sudo dmsetup table docker-8:1-123141-pool $ sudo dmsetup table docker-8:1-123141-pool
0 209715200 thin-pool 7:1 7:0 128 32768 1 skip_block_zeroing 0 209715200 thin-pool 7:1 7:0 128 32768 1 skip_block_zeroing
``` ```
c. Calculate the real total sectors of the thin pool now. 3. Calculate the real total sectors of the thin pool now.
Change the second number of the table info (i.e. the disk end sector) to Change the second number of the table info (i.e. the disk end sector) to
reflect the new number of 512 byte sectors in the disk. For example, as the reflect the new number of 512 byte sectors in the disk. For example, as the
new loop size is 200GB, change the second number to 419430400. new loop size is 200GB, change the second number to 419430400.
d. Reload the thin pool with the new sector number 4. Reload the thin pool with the new sector number
```bash ```bash
$ sudo dmsetup suspend docker-8:1-123141-pool \ $ sudo dmsetup suspend docker-8:1-123141-pool \
&& sudo dmsetup reload docker-8:1-123141-pool --table '0 419430400 thin-pool 7:1 7:0 128 32768 1 skip_block_zeroing' \ && sudo dmsetup reload docker-8:1-123141-pool --table '0 419430400 thin-pool 7:1 7:0 128 32768 1 skip_block_zeroing' \
&& sudo dmsetup resume docker-8:1-123141-pool && sudo dmsetup resume docker-8:1-123141-pool
``` ```
#### The device_tool #### The device_tool
@ -548,63 +549,64 @@ disk partition.
1. Extend the volume group (VG) `vg-docker`. 1. Extend the volume group (VG) `vg-docker`.
```bash ```bash
$ sudo vgextend vg-docker /dev/sdh1 $ sudo vgextend vg-docker /dev/sdh1
Volume group "vg-docker" successfully extended Volume group "vg-docker" successfully extended
``` ```
Your volume group may use a different name. Your volume group may use a different name.
2. Extend the `data` logical volume(LV) `vg-docker/data` 2. Extend the `data` logical volume(LV) `vg-docker/data`
```bash ```bash
$ sudo lvextend -l+100%FREE -n vg-docker/data $ sudo lvextend -l+100%FREE -n vg-docker/data
Extending logical volume data to 200 GiB Extending logical volume data to 200 GiB
Logical volume data successfully resized Logical volume data successfully resized
``` ```
3. Reload devicemapper thin pool. 3. Reload devicemapper thin pool.
a. Get the pool name. 1. Get the pool name.
```bash ```bash
$ sudo dmsetup status | grep pool $ sudo dmsetup status | grep pool
docker-253:17-1835016-pool: 0 96460800 thin-pool 51593 6270/1048576 701943/753600 - rw no_discard_passdown queue_if_no_space docker-253:17-1835016-pool: 0 96460800 thin-pool 51593 6270/1048576 701943/753600 - rw no_discard_passdown queue_if_no_space
``` ```
The name is the string before the colon. The name is the string before the colon.
b. Dump the device mapper table. 2. Dump the device mapper table.
```bash ```bash
$ sudo dmsetup table docker-253:17-1835016-pool $ sudo dmsetup table docker-253:17-1835016-pool
0 96460800 thin-pool 252:0 252:1 128 32768 1 skip_block_zeroing 0 96460800 thin-pool 252:0 252:1 128 32768 1 skip_block_zeroing
``` ```
c. Calculate the real total sectors of the thin pool now. we can use `blockdev` to get the real size of data lv. 3. Calculate the real total sectors of the thin pool now. we can use `blockdev` to get the real size of data lv.
Change the second number of the table info (i.e. the number of sectors) to Change the second number of the table info (i.e. the number of sectors) to
reflect the new number of 512 byte sectors in the disk. For example, as the reflect the new number of 512 byte sectors in the disk. For example, as the
new data `lv` size is `264132100096` bytes, change the second number to new data `lv` size is `264132100096` bytes, change the second number to
`515883008`. `515883008`.
```bash ```bash
$ sudo blockdev --getsize64 /dev/vg-docker/data $ sudo blockdev --getsize64 /dev/vg-docker/data
264132100096 264132100096
``` ```
d. Then reload the thin pool with the new sector number. 4. Then reload the thin pool with the new sector number.
```bash ```bash
$ sudo dmsetup suspend docker-253:17-1835016-pool \ $ sudo dmsetup suspend docker-253:17-1835016-pool \
&& sudo dmsetup reload docker-253:17-1835016-pool --table '0 515883008 thin-pool 252:0 252:1 128 32768 1 skip_block_zeroing' \ && sudo dmsetup reload docker-253:17-1835016-pool \
&& sudo dmsetup resume docker-253:17-1835016-pool --table '0 515883008 thin-pool 252:0 252:1 128 32768 1 skip_block_zeroing' \
``` && sudo dmsetup resume docker-253:17-1835016-pool
```
## Device Mapper and Docker performance ## Device Mapper and Docker performance