Stratis is a local storage management solution for Linux Operating System and aims to ease the work of a system administrator by advanced storage options like snapshots, thin provisioning, pool-based management, monitoring, Tiering, etc. apart from being very simple to use.
Stratis is a user-space daemon that configures and monitors existing components from Linux’s device-mapper subsystem, as well as the XFS filesystem. Stratis Pool which is the central attraction of the Stratis tool is a collection of one or more local disks or partitions. Once the pool is created, administrators can create volumes.
Currently, Stratis supports block devices based on LVM Logical Volumes, mdraid, dm-multipath, iSCSI, and LUKS (crypto), as well as hard drives, SSDs, and NVMe storage devices.
Stratis Layers
Internally, Stratis uses the Backstore subsystem to manage the block devices, and the Thinpool subsystem to manage the pools. The Backstore subsystem has a data tier that maintains the on-disk metadata on block devices and detects and corrects data corruption. The cache tier uses high-performance block devices to act as a cache on top of the data tier.
The Thin pool subsystem manages the thin-provisioned volumes associated with the Stratis filesystems. This subsystem uses the dm-thin device-mapper driver to replace LVM on the virtual volume sizing and management. dm-thin creates volumes with a large virtual size, formatted with XFS, but with a small physical size. As the physical size nears full, Stratis enlarges it automatically.
Features:
- Thin provisioning
- Filesystem snapshots
- Pool-based management
- Monitoring
Stratis Terminologies:
When working with Stratis, you’ll often come across the following terminologies:
- blockdev: This is a block device, such as a disk or a disk partition.
- pool: A pool is composed of one or more block devices with a fixed total size, equal to the size of the block devices.
- filesystem: Each pool can contain one or more file systems, which store files. A filesystem does not have a fixed total size since it is thinly provisioned. If the size of the data approaches the virtual size of the file system, Stratis grows the thin volume and the file system automatically.
Stratis Software components:
Stratis provides two software components:
- stratisd daemon: This manages collections of block devices and provides a D-Bus API.
- stratis-cli: This provides a command-line tool stratis which itself uses the D-Bus API to communicate with stratisd.
Step 1: Install Stratis on RHEL 8 / CentOS 8
RHEL 8 is distributed with stratisd and stratis-cli which can be easily installed using the yum package management tool.
[root@redaix ~]# yum install stratisd stratis-cli -y
Updating Subscription Management repositories.
Last metadata expiration check: 0:50:34 ago on Sun 31 May 2020 04:53:08 AM PDT.
Dependencies resolved.
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Package Architecture Version Repository Size
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Installing:
stratis-cli noarch 2.0.0-1.el8 rhel-8-for-x86_64-appstream-rpms 60 k
stratisd x86_64 2.0.0-4.el8 rhel-8-for-x86_64-appstream-rpms 1.2 M
Installing dependencies:
python3-dbus-client-gen noarch 0.4-1.el8 rhel-8-for-x86_64-appstream-rpms 26 k
python3-dbus-python-client-gen noarch 0.7-3.el8 rhel-8-for-x86_64-appstream-rpms 28 k
python3-dbus-signature-pyparsing noarch 0.03-2.el8 rhel-8-for-x86_64-appstream-rpms 19 k
python3-into-dbus-python noarch 0.06-2.el8 rhel-8-for-x86_64-appstream-rpms 27 k
python3-justbases noarch 0.9-6.el8 rhel-8-for-x86_64-appstream-rpms 45 k
python3-justbytes noarch 0.11-2.el8 rhel-8-for-x86_64-appstream-rpms 40 k
Transaction Summary
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Install 8 Packages
You can get full package details using the rpm command:
[root@redaix ~]# rpm -qi stratisd stratis-cli
Name : stratisd
Version : 2.0.0
Release : 4.el8
Architecture: x86_64
Install Date: Sun 31 May 202005:44:10 AM PDT
Group : Unspecified
Size : 4037577
License : MPLv2.0
Signature : RSA/SHA256, Tue 19 Nov 201909:19:51 AM PST, Key ID 199e2f91fd431d51
Source RPM : stratisd-2.0.0-4.el8.src.rpm
Build Date : Tue12 Nov 201906:21:20 AM PST
Build Host : x86-vm-08.build.eng.bos.redhat.com
Relocations : (notrelocatable)
Packager : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
Vendor : Red Hat, Inc.
URL : https://github.com/stratis-storage/stratisd
Summary : Daemon that manages block devices to create filesystems
Description :
Daemon that manages block devices to create filesystems.
Name : stratis-cli
Version : 2.0.0
Release : 1.el8
Architecture: noarch
Install Date: Sun 31 May 202005:44:13 AM PDT
Group : Unspecified
Size : 184831
License : ASL2.0
Signature : RSA/SHA256, Tue 19 Nov 201909:19:46 AM PST, Key ID 199e2f91fd431d51
Source RPM : stratis-cli-2.0.0-1.el8.src.rpm
Build Date : Sun10 Nov 201909:37:36 AM PST
Build Host : ppc-062.build.eng.bos.redhat.com
Relocations : (notrelocatable)
Packager : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
Vendor : Red Hat, Inc.
URL : https://github.com/stratis-storage/stratis-cli
Summary : Command-line tool for interacting with the Stratis daemon
Description :
stratis provides a command-line interface (CLI) for
interacting with the Stratis daemon, stratisd. stratis
interacts with stratisd via D-Bus.Step 2: Start Stratis services:
After installing Stratis packages, you’ll need to start the service and enable it.
[root@redaix ~]# systemctl start stratisd.service
[root@redaix ~]# systemctl enable stratisd.service --nowStep 3: Creating a Stratis pool
For this, you’ll require block devices which are not in use or mounted to create Stratis pool from. The block devices should be at least 1 GiB in size each.
[root@redaix ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 1024M 0 rom
nvme0n1 259:0 0 20G 0 disk
├─nvme0n1p1 259:1 0 300M 0 part /boot
├─nvme0n1p2 259:2 0 2G 0 part [SWAP]
└─nvme0n1p3 259:3 0 17.7G 0 part /
nvme0n2 259:4 0 20G 0 disk
nvme0n3 259:5 0 5G 0 disk
nvme0n4 259:6 0 5G 0 diskI’ll create the first pool with single block device nvme0n2 and the other pool with two block devices nvme0n3 & nvme0n4
These block devices should not have a partition table, confirm with:
[root@redaix ~]# blkid -p /dev/nvme0n2
/dev/nvme0n2: UUID="3ddbc7bb-d3a2-4a38-88da-579cbfa7edaa" TYPE="vdo" USAGE="other"If it has a partition table and you want to use it, first clear a device so that it can be used by Stratis.
[root@redaix ~]# wipefs -a /dev/nvme0n2
/dev/nvme0n2: 8 bytes were erased at offset 0x00000000 (vdo): 646d 76646f 303031
[root@redaix ~]# blkid -p /dev/nvme0n2
[root@redaix ~]# blkid -p /dev/nvme0n3
[root@redaix ~]# blkid -p /dev/nvme0n4
[root@redaix ~]#Create a pool with one block device:
To create a pool with one block device /dev/nvme0n2 use:
[root@redaix ~]# stratis pool create mypool1 /dev/nvme0n2
List available pools with:
[root@redaix ~]# stratis pool list
Name Total Physical
mypool1 20 GiB / 37.64 MiB / 19.96 GiBStep 4: Creating a filesystem from the pool
Once you have your pools ready, you can create a Stratis filesystem on a pool using the syntax:
#stratis fs create <pool_name> <filesystem_name>Create a filesystem on mypool1
[root@redaix ~]# stratis fs create mypool1 myfsCreate filesystem on mypool2
[root@redaix ~]# stratis fs create mypool2 data
[root@redaix ~]# stratis fs create mypool2 webTo list created filesystems, use:
[root@redaix ~]# stratis fs list
Pool Name Name Used Created Device UUID
mypool1 myfs 546 MiB May 31 2020 07:18 /stratis/mypool1/myfs 5cd703ee68224195aad2060c5d9ae9d1
mypool2 data 546 MiB May 31 2020 07:20 /stratis/mypool2/data f0a95a27dfe14d388d8b4724fd15ffc0
mypool2 web 546 MiB May 31 2020 07:20 /stratis/mypool2/web 4c8a7463d0fc45628591d9e9ea545804You can also limit output to specified pool:
[root@redaix ~]# stratis fs list mypool2
Pool Name Name Used Created Device UUID
mypool2 data 546 MiB May 31 2020 07:20 /stratis/mypool2/data f0a95a27dfe14d388d8b4724fd15ffc0
mypool2 web 546 MiB May 31 2020 07:20 /stratis/mypool2/web 4c8a7463d0fc45628591d9e9ea545804Step 5: Mounting a Stratis file system
To mount the file system, use the entries that Stratis maintains in the /dev/stratis/ directory. See examples below:
Create directories, /myfs. /data & /web
[root@redaix ~]# mount /stratis/mypool1/myfs /myfs
[root@redaix ~]# mount /stratis/mypool2/data /data
[root@redaix ~]# mount /stratis/mypool2/web /webCheck current mount points
[root@redaix ~]# df -Th | grep stratis
/dev/mapper/stratis-1-2a95bb640590433f864b4d322ddece10-thin-fs-5cd703ee68224195aad2060c5d9ae9d1 xfs 1.0T 7.2G 1017G 1% /myfs
/dev/mapper/stratis-1-5dc6d5aafd83443da8bd6adcecaf0b88-thin-fs-f0a95a27dfe14d388d8b4724fd15ffc0 xfs 1.0T 7.2G 1017G 1% /data
/dev/mapper/stratis-1-5dc6d5aafd83443da8bd6adcecaf0b88-thin-fs-4c8a7463d0fc45628591d9e9ea545804 xfs 1.0T 7.2G 1017G 1% /webAdd a persistent mount point to /etc/fstab
To configure persistent mount, get the UUID of the filesystem.
[root@redaix ~]# blkid -p /stratis/mypool1/myfs
/stratis/mypool1/myfs: UUID="5cd703ee-6822-4195-aad2-060c5d9ae9d1"TYPE="xfs"USAGE="filesystem"
[root@redaix ~]# blkid -p /stratis/mypool2/data
/stratis/mypool2/data: UUID="f0a95a27-dfe1-4d38-8d8b-4724fd15ffc0"TYPE="xfs"USAGE="filesystem"
[root@redaix ~]# blkid -p /stratis/mypool2/web
/stratis/mypool2/web: UUID="4c8a7463-d0fc-4562-8591-d9e9ea545804"TYPE="xfs"USAGE="filesystem"Copy the printed UUID and add mount options to /etc/fstab file
[root@redaix ~]# echo "UUID=5cd703ee-6822-4195-aad2-060c5d9ae9d1 /myfs xfs defaults,x-systemd.requires=stratisd.service 0 0" | sudo tee -a /etc/fstab
UUID=5cd703ee-6822-4195-aad2-060c5d9ae9d1 /myfs xfs defaults,x-systemd.requires=stratisd.service 00
[root@redaix ~]# echo "UUID=f0a95a27-dfe1-4d38-8d8b-4724fd15ffc0 /data xfs defaults,x-systemd.requires=stratisd.service 0 0" | sudo tee -a /etc/fstab
UUID=f0a95a27-dfe1-4d38-8d8b-4724fd15ffc0 /data xfs defaults,x-systemd.requires=stratisd.service 00
[root@redaix ~]# echo "UUID=4c8a7463-d0fc-4562-8591-d9e9ea545804 /web xfs defaults,x-systemd.requires=stratisd.service 0 0" | sudo tee -a /etc/fstab
UUID=4c8a7463-d0fc-4562-8591-d9e9ea545804 /web xfs defaults,x-systemd.requires=stratisd.service 00Stratis Administration Tasks & Commands
- Add a disk to an existing pool
- Create Stratis snapshots
- Revert a Stratis file system to a previous snapshot
- Removing a Stratis snapshot
- Renaming a file system
- Removing a Stratis pool
Add a disk to an existing pool
Verify present disks
[root@redaix ~]# stratis blockdev
Pool Name Device Node Physical Size Tier
mypool2 /dev/nvme0n3 5 GiB Data
mypool2 /dev/nvme0n4 5 GiB DataTo add another disk to the pool, use:
[root@redaix ~]# stratis pool add-data mypool2 /dev/nvme0n2Verify post verification:
[root@redaix ~]# stratis blockdev
Pool Name Device Node Physical Size Tier
mypool2 /dev/nvme0n2 20 GiB Data
mypool2 /dev/nvme0n3 5 GiB Data
mypool2 /dev/nvme0n4 5 GiB Data
Create Stratis snapshots
Stratis Snapshot is a read/writeable thinly provisioned point-in-time copy of the source FS.
To create Stratis snapshot, use:
sudo stratis fs snapshot <poolname><fsname><snapshotname>Example:
[root@redaix ~]# stratis fs snapshot mypool2 web websnapshot-$(date +%Y-%m-%d)Confirm:
[root@redaix ~]# stratis filesystem list mypool2
Pool Name Name Used Created Device UUID
mypool2 websnapshot-2020-05-31 546 MiB May 31 2020 08:51 /stratis/mypool2/websnapshot-2020-05-31 e6f993bae71046bc9cd94f0a97cfa64b
mypool2 data 546 MiB May 31 2020 07:20 /stratis/mypool2/data f0a95a27dfe14d388d8b4724fd15ffc0
mypool2 web 546 MiB May 31 2020 07:20 /stratis/mypool2/web 4c8a7463d0fc45628591d9e9ea545804You can mount and operate Snapshot independent of the source file system.
[root@redaix ~]# mount /stratis/mypool2/websnapshot-2020-05-31 /mnt
[root@redaix ~]# cd /mnt
[root@redaix mnt]# ls
[root@redaix mnt]# touch test_file{1..10}
[root@redaix mnt]# ls
test_file1 test_file2 test_file4 test_file6 test_file8
test_file10 test_file3 test_file5 test_file7 test_file9Revert a Stratis file system to a previous snapshot
It is possible to revert a Statis file system to the previously created snapshot. See below
First Unmount and remove the original file system:
[root@redaix mnt]# umount /web
[root@redaix mnt]# stratis filesystem destroy mypool2 webThen create a copy of the snapshot under the name of the original file system:
[root@redaix mnt]# stratis filesystem snapshot mypool2 websnapshot-2020-05-31 web
Mount the snapshot & filesystem should contain the data we added to the snapshot
[root@redaix ~]# mount /stratis/mypool2/web /web
[root@redaix ~]# cd /web
[root@redaix web]# ls
test_file1 test_file2 test_file4 test_file6 test_file8
test_file10 test_file3 test_file5 test_file7 test_file9Also change UUID on /etc/fstab to match new filesystem UUID.
[root@redaix web]# blkid -p /stratis/mypool2/web
/stratis/mypool2/web: UUID="e84d1fb6-6b6a-4653-acf1-4ef097c4971c"TYPE="xfs"USAGE="filesystem"
[root@redaix web]# grep web /etc/fstab
UUID=4c8a7463-d0fc-4562-8591-d9e9ea545804 /web xfs defaults,x-systemd.requires=stratisd.service 0 0Removing a Stratis snapshot
To remove the snapshot, unmount the snapshot
[root@redaix ~]# umount /mntNow destroy the snapshot
stratis filesystem destroy <pool_name><snapshot_name>Example:
[root@redaix ~]# stratis filesystem destroy mypool2 websnapshot-2020-05-31Post Verification:
[root@redaix ~]# stratis filesystem list mypool2
Pool Name Name Used Created Device UUID
mypool2 web 546 MiB May 31 2020 09:06 /stratis/mypool2/web e84d1fb66b6a4653acf14ef097c4971c
mypool2 data 546 MiB May 31 2020 07:20 /stratis/mypool2/data f0a95a27dfe14d388d8b4724fd15ffc0Renaming a file system
To rename a file system, use the below syntax:
stratis filesystem rename <pool_name><old_fsname><new_fsname>The example below renames “web” filesystem to “backups”
[root@redaix ~]# stratis filesystem rename mypool2 web backupsPost verification:
[root@redaix ~]# stratis filesystem list mypool2
Pool Name Name Used Created Device UUID
mypool2 backups 546 MiB May 31 2020 09:06 /stratis/mypool2/backups e84d1fb66b6a4653acf14ef097c4971c
mypool2 data 546 MiB May 31 2020 07:20 /stratis/mypool2/data f0a95a27dfe14d388d8b4724fd15ffc0Removing a Stratis Pool
To completely destroy a Stratis Pool, you need to:
- Unmount all filesystems on the pool
- Destroy the filesystems
- Destroy the pool
In below example, we will destroy mypool1
List available filesystems
[root@redaix ~]# stratis filesystem list mypool1
Pool Name Name Used Created Device UUID
mypool1 myfs 546 MiB May 31 2020 07:18 /stratis/mypool1/myfs 5cd703ee68224195aad2060c5d9ae9d1Unmount the filesystem
[root@redaix ~]# umount /myfsDestroy filesystem
[root@redaix ~]# stratis filesystem destroy mypool1 myfsDestroy the pool
[root@redaix ~]# stratis pool destroy mypool1Verify that the pool no longer exists
[root@redaix ~]# stratis pool list
Name Total Physical
mypool2 10 GiB / 1.11 GiB / 8.89 GiBRemove /etc/fstab lines for destroyed filesystem
[root@redaix ~]# vi /etc/fstabReference:
Setting up Stratis file systems
That’s all friend’s
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