Stratis is a Linux local storage management tool that aims to enable easy use of advanced storage features such as thin provisioning, snapshots, and pool-based management & monitoring.
Stratis daemon is originally developed by Red Hat. Stratis is written in RUST language and distributed under Mozilla Public License 2.0. Stratis provides ZFS/Btrfs-style features by integrating layers of existing technology: Linux's device mapper subsystem, and the XFS filesystem.
In this article, we will install and configure Stratis local storage on CentOS 8.
Table of Contents:
- Stratis Storage Features
- Stratis Storage Building Blocks
- Environment Specification
- Installing Stratis Local Storage on CentOS 8
- Creating Stratis Storage Pools
- Add a Block Device to Existing Stratis Storage Pool
- Create Stratis Storage Pool from Multiple Block Devices
- Creating Stratis FileSystems
- Mounting the Stratis FileSystems
- Creating Snapshot of Stratis FileSystems
- Removing a Stratis FileSystem
- Removing a Stratis Storage Pool
- Conclusion
Stratis Storage Features:
Stratis storage provides following advanced features.
- Thin Provisioning
- Pool Based Management and Monitoring
- FileSystem Snapshots
Stratis Storage Building Blocks:
To understand Stratis Storage architecture, you need know the following three buidling blocks.
- Block Device: A block device can be a disk, partition or Logical Volume (LVM).
- Storage Pool: A Stratis storage pool consist of one or more Block devices.
- FileSystem: A FileSystem is a final ready to mount storage. It is provisioned from a Storage Pool.
Environment Specification:
We have provisioned virtual machine with minimally installed CentOS 8 with following specification.
- CPU - 3.4 Ghz (2 cores)
- Memory - 1 GB
- Storage - 20 GB
- Operating System - CentOS 8.0
- Hostname - stratis-01.centlinux.com
- IP Address - 192.168.116.206 /24
Installing Stratis Local Storage on CentOS 8:
Connect with stratis-01.centlinux.com using ssh as root user.
To setup Stratis Local Storage on CentOS 8, we have to install following two packages.
- stratisd - Stratis Daemon
- stratis-cli - Command-line interface to manage stratis local storage.
Both packages are available in default dnf repository, therefore, we are installing it using dnf command.
# dnf install -y stratisd stratis-cli
Installer automatically enables the stratisd service. We are only required to start stratisd service once.
# systemctl start stratisd.service
Stratis has been successfully installed on CentOS 8.
Creating Stratis Storage Pools:
We have added four hard disks (10GB each) in our CentOS 8 virtual machine. We will use these disks as block devices for our Stratis storage pools.
# lsblk | grep 'sd[b-e]'
sdb 8:16 0 10G 0 disk
sdc 8:32 0 10G 0 disk
sdd 8:48 0 10G 0 disk
sde 8:64 0 10G 0 disk
Check current storage pools.
# stratis pool list
Name Total Physical Size Total Physical Used
Right now, we have no storage pool defined.
Let's create a Stratis storage pool using /dev/sdb block device.
# stratis pool create db_pool /dev/sdb
Check current storage pools again.
# stratis pool list
Name Total Physical Size Total Physical Used
db_pool 10 GiB 52 MiB
Add a Block Device to Existing Stratis Storage Pool:
Let's add our second disk to the db_pool stratis storage pool.
# stratis pool add-data db_pool /dev/sdc
Check current storage pools list.
# stratis pool list
Name Total Physical Size Total Physical Used
db_pool 20 GiB 56 MiB
You can see that the total size of the db_pool has been increased.
Create Stratis Storage Pool from Multiple Block Devices:
We can alternatively, create a pool using multiple block devices in a single command.
# stratis pool create backup_pool /dev/sdd /dev/sde
Check current storage pools now.
# stratis pool list
Name Total Physical Size Total Physical Used
backup_pool 20 GiB 56 MiB
db_pool 20 GiB 56 MiB
Creating Stratis FileSystems:
We have a Stratis storage pool, we can now use it to provision Stratis filesystems as follows.
# stratis fs create db_pool prod_db_fs # stratis fs create db_pool test_db_fs
Check the list of Stratis filesystems.
# stratis fs list
Pool Name Name Used Created Device UUID
db_pool prod_db_fs 546 MiB Dec 17 2019 22:22 /stratis/db_pool/prod_db_fs d62f6884dffc40a6b8024784b7f60ca8
db_pool test_db_fs 546 MiB Dec 17 2019 22:22 /stratis/db_pool/test_db_fs 9ce32861f56b408597550d88e9bf5a44
Mounting the Stratis FileSystems:
We have create two Stratis filesystems, one for our Production database (prod_db_fs) and the other for the Test database (test_db_fs).
Now it's time to mount these filesystems.
To mount these filesystems, we need to identify the UUID of the filesystems. We can obtain the UUID using following command.
# blkid | grep /dev/mapper/stratis
/dev/mapper/stratis-1-c943c04939f5432cbe4d3d9985cd462e-thin-fs-d62f6884dffc40a6b8024784b7f60ca8: UUID="d62f6884-dffc-40a6-b802-4784b7f60ca8" TYPE="xfs"
/dev/mapper/stratis-1-c943c04939f5432cbe4d3d9985cd462e-thin-fs-9ce32861f56b408597550d88e9bf5a44: UUID="9ce32861-f56b-4085-9755-0d88e9bf5a44" TYPE="xfs"
We can use these UUIDs to persistently mount our Stratis filesystems.
Create directories to mount Stratis filesystems.
# mkdir /mnt/{prod,test}
Edit /etc/fstab to add automount entries.
# vi /etc/fstab
Add entries for our Stratis filesystems therein.
UUID=d62f6884-dffc-40a6-b802-4784b7f60ca8 /mnt/prod xfs defaults,x-systemd.requires=stratisd.service 0 0
UUID=9ce32861-f56b-4085-9755-0d88e9bf5a44 /mnt/test xfs defaults,x-systemd.requires=stratisd.service 0 0
Execute following command to update systemd units generated from this file.
# systemctl daemon-reload
Mount all entries in /etc/fstab using mount command.
# mount -a
Verify that our Stratis filesystem are mounted correctly.
# mount | grep /dev/mapper/stratis
/dev/mapper/stratis-1-c943c04939f5432cbe4d3d9985cd462e-thin-fs-d62f6884dffc40a6b8024784b7f60ca8 on /mnt/prod type xfs (rw,relatime,seclabel,attr2,inode64,sunit=2048,swidth=2048,noquota,x-systemd.requires=stratisd.service)
/dev/mapper/stratis-1-c943c04939f5432cbe4d3d9985cd462e-thin-fs-9ce32861f56b408597550d88e9bf5a44 on /mnt/test type xfs (rw,relatime,seclabel,attr2,inode64,sunit=2048,swidth=2048,noquota,x-systemd.requires=stratisd.service)
Creating Snapshot of Stratis FileSystems:
Copy some data in /mnt/prod directory.
# cp -r /etc/[a-f]* /mnt/prod
We can take snapshot of the prod_db_fs filesystem using following command.
# stratis fs snapshot db_pool prod_db_fs prod_db_bkp_17dev2019
Check Stratis filesystems.
# stratis fs list
Pool Name Name Used Created Device UUID
db_pool prod_db_bkp_17dev2019 577 MiB Dec 17 2019 23:28 /stratis/db_pool/prod_db_bkp_17dev2019 b4583769df9e40d790a55f11b705b65d
db_pool prod_db_fs 577 MiB Dec 17 2019 22:22 /stratis/db_pool/prod_db_fs d62f6884dffc40a6b8024784b7f60ca8
db_pool test_db_fs 546 MiB Dec 17 2019 22:22 /stratis/db_pool/test_db_fs 9ce32861f56b408597550d88e9bf5a44
A Stratis Snapshot is also a Stratis filesystem, therefore, we can mount it inplace of the actual filesystem to restore a previous state of data, without required to remove the existing filesystem.
Removing a Stratis FileSystem:
To remove a filesystem, make sure it is not mounted and then remove it using following command.
# umount /mnt/test # stratis fs destroy db_pool test_db_pool
Removing a Stratis Storage Pool:
To remove a Stratis Storage, make sure that, there isn't any filesystem exists within that pool.
Remove an existing storage pool using following command.
# stratis pool destroy backup_pool
Conclusion:
We have successfully installed and configured Stratis local storage on CentOS 8 and explored some of it's advanced features like thin-provisioning and snapshots.
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