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System-docker and RootFS
When you ssh into RancherOS, you actually access the console container. The default console will automatically clean up the data, except for the following directories:
# These are the main ones
/opt
/home/
/var/lib/docker
/mnt
/var/log
...
...
If you put the data in these directories, you actually write directly to the root disk.
The system-docker data is written to the root disk, so it is not recommended for users to run their containers under system-docker.
If the user can use it friendly, two places still need attention:
-
the only thing that needs attention is the
/var/logdirectory. It is necessary to clean it regularly. -
the container logs in system-docker, they are in json-file format. This part of the change should be slow.
User-docker
The user-docker data is written to the root disk by default. This part is necessary to use additional disk. Can refer to the following settings:
#cloud-config
mounts:
- - /dev/sdb
- /var/lib/docker/mnt
- ext4
- ""
rancher:
docker:
graph: /var/lib/docker/mnt
# check user docker
$ docker info
Name: rancher
ID: BU6T:6LTB:VKUU:GZM2:OGCR:IIVZ:6MVK:II73:KVVE:EEGI:CGPT:FWYS
***Docker Root Dir: /var/lib/docker/mnt****
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
...
# check mountinfo
$ df -hT
....
/dev/sdb ext4 9.8G 36.2M 9.2G 0% /var/lib/docker/mnt
....
Others
If you are not using the default console, then most of the data you write will be saved in the root disk.
In the system, it is necessary to run a monitor to detect disk usage at all times.
How to custom partition layout
When users use the default ros install, ROS will automatically create one partition on the root disk.
It will be the only partition with the label RANCHER_STATE.
But sometimes users want to be able to customize the root disk partition to isolate the data.
Use RANCHER_STATE partition
As mentioned above, the default mode is that ROS will automatically create one partition with the label RANCHER_STATE.
In addition, we can have other partitions, e.g.: two partitions, one is RANCHER_STATE and the other is a normal partition.
First boot a ROS instance from ISO, then manually format and partition /dev/sda , the reference configuration is as follows:
[root@rancher oem]# fdisk -l
Disk /dev/sda: 5 GiB, 5377622016 bytes, 10503168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x9fff87e9
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 7503167 7501120 3.6G 83 Linux
/dev/sda2 7503872 10503167 2999296 1.4G 83 Linux
[root@rancher oem]# blkid
/dev/sda1: LABEL="RANCHER_STATE" UUID="512f212b-3130-458e-a2d1-1d601c34d4e4" TYPE="ext4" PARTUUID="9fff87e9-01"
/dev/sda2: UUID="3828e3ac-b825-4898-9072-45da9d37c2a6" TYPE="ext4" PARTUUID="9fff87e9-02"
Then install ROS to the disk with ros install -t noformat -d /dev/sda ....
After rebooting, you can use /dev/sda2. For example, changing the data root of user-docker:
$ ros config set mounts '[["/dev/sda2","/mnt/s","ext4",""]]’
$ ros config set rancher.docker.graph /mnt/s
$ reboot
Use RANCHER_BOOT partition
When you only use the RRACHER_STATE partition, the bootloader will be installed in the /boot directory.
$ system-docker run -it --rm -v /:/host alpin
ls /host/boot
...
If you want to use a separate boot partition, you also need to boot a ROS instance from ISO, then manually format and partition /dev/sda:
[root@rancher rancher]# fdisk -l
Disk /dev/sda: 5 GiB, 5377622016 bytes, 10503168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe32b3025
Device Boot Start End Sectors Size Id Type
/dev/sda1 2048 2503167 2501120 1.2G 83 Linux
/dev/sda2 2504704 7503167 4998464 2.4G 83 Linux
/dev/sda3 7503872 10503167 2999296 1.4G 83 Linux
[root@rancher rancher]# mkfs.ext4 -L RANCHER_BOOT /dev/sda1
[root@rancher rancher]# mkfs.ext4 -L RANCHER_STATE /dev/sda2
[root@rancher rancher]# mkfs.ext4 /dev/sda3
[root@rancher rancher]# blkid
/dev/sda1: LABEL="RANCHER_BOOT" UUID="43baeac3-11f3-4eed-acfa-64daf66b26c8" TYPE="ext4" PARTUUID="e32b3025-01"
/dev/sda2: LABEL="RANCHER_STATE" UUID="16f1ecef-dbe4-42a2-87a1-611939684e0b" TYPE="ext4" PARTUUID="e32b3025-02"
/dev/sda3: UUID="9f34e161-0eee-48f9-93de-3b7c54dea437" TYPE="ext4" PARTUUID="c9b8f181-03"
Then install ROS to the disk with ros install -t noformat -d /dev/sda ....
After rebooting, you can check the boot partition:
[root@rancher rancher]# mkdir /boot
[root@rancher rancher]# mount /dev/sda1 /boot
[root@rancher rancher]# ls -ahl /boot/
total 175388
drwxr-xr-x 4 root root 4.0K Sep 27 03:35 .
drwxr-xr-x 1 root root 4.0K Sep 27 03:38 ..
-rw-r--r-- 1 root root 24 Sep 27 03:05 append
-rw-r--r-- 1 root root 128 Sep 27 03:35 global.cfg
-rw-r--r-- 1 root root 96.8M Sep 27 03:05 initrd-2f9fc0b
If you are not using the first partition as a BOOT partition, you need to set BOOT flag via the fdisk tool.
Use RANCHER_OEM partition
If you format any partition with the label RANCHER_OEM, ROS will mount this partition to /usr/share/ros/oem:
[root@rancher rancher]# blkid
/dev/sda2: LABEL="RANCHER_OEM" UUID="4f438455-63a3-4d29-ac90-50adbeced412" TYPE="ext4" PARTUUID="9fff87e9-02"
[root@rancher rancher]# df -hT | grep sda2
/dev/sda2 ext4 1.4G 4.3M 1.3G 0% /usr/share/ros/oem
Currently, this OEM directory is hardcoded and not configurable.
Use RANCHER_SWAP partition
Suppose you have a partition(/dev/sda2) and you want to use it as a SWAP partition:
$ mkswap -L RANCHER_SWAP /dev/sda2
$ blkid
/dev/sda1: LABEL="RANCHER_STATE" UUID="512f212b-3130-458e-a2d1-1d601c34d4e4" TYPE="ext4" PARTUUID="9fff87e9-01"
/dev/sda2: LABEL="RANCHER_SWAP" UUID="772b6e76-f89c-458e-931e-10902d78d3e4" TYPE="swap" PARTUUID="9fff87e9-02"
After you install ROS to the disk, you can add the runcmd to enable SWAP:
runcmd:
- swapon -L RANCHER_SWAP
Then check the memory information:
[root@rancher rancher]# free -m
total used free shared buffers cached
Mem: 1996 774 1221 237 20 614
-/+ buffers/cache: 139 1856
Swap: 487 0 487
Reference
Resources