Storage management under Fedora made easy: System Storage Manager
One of the innovations of Fedora 18 is the new System Storage Manager as I mentioned yesterday. This tool enables the central administration of storage devices. Are the times of reading manpages finally over for newbies? I had a deeper look at the SSM - and was pleasantly suprised. The System Storage Manager can be installed comfortably using Yum or rather DNF:
1# yum install system-storage-manager
2# dnf install system-storage-manager
The concept of SSM reminds me on diskpart from Windows and the in the HP-UX world good-known vxdisk utility - those tools also allow storage management using simple and self-explanatory commands. But what can SSM do at all?
- create and check ext3-, ext4, xfs- and btrfs volumes
- list devices, volumes and LVM/RAID/btrfs pools (
list dev/vol/pool) - create, expand and delete LVM/RAID/btrfs pools
- remove and delete volumes, filesystems
- create snapshots (
snapshot)
As you can see, the commands are self-explanatory - the applicable options sound like well-known mkfs/lvm commands. So SSM is very transit-friendly.
Create volumes
Using three short commands 1 LVM volumegroup is created with two logical volumes, from which one is resized afterwards:
1# ssm list dev
2------------------------------------------------------------
3Device Free Used Total Pool Mount point
4------------------------------------------------------------
5/dev/sda 20.00 GB PARTITIONED
6/dev/sda1 500.00 MB /boot
7/dev/sda2 0.00 KB 19.51 GB 19.51 GB fedora
8/dev/sdb 10.00 GB
9/dev/sdc 10.00 GB
10------------------------------------------------------------
11
12# ssm create -s 6G --fstype ext4 /dev/sdb
13 No physical volume label read from /dev/sdb
14 Physical volume "/dev/sdb" successfully created
15 Volume group "lvm_pool" successfully created
16 Logical volume "lvol001" created
17# ssm resize -s 5G lvm_pool/lvol001
18# ssm create -s 2G -n crash_vol --fstype ext4 -p lvm_pool
19
20# ssm list vol
21-----------------------------------------------------------------------------------------------
22Volume Pool Volume size FS FS size Free Type Mount point
23-----------------------------------------------------------------------------------------------
24...
25/dev/lvm_pool/lvol001 lvm_pool 5.00 GB ext4 5.00 GB 4.53 GB linear
26/dev/lvm_pool/crash_vol lvm_pool 2.00 GB ext4 2.00 GB 1.80 GB linear
27-----------------------------------------------------------------------------------------------
28
29# ssm list pool
30----------------------------------------------------
31Pool Type Devices Free Used Total
32----------------------------------------------------
33fedora lvm 1 0.00 KB 19.51 GB 19.51 GB
34lvm_pool lvm 1 3.00 GB 7.00 GB 10.00 GB
35----------------------------------------------------
Snapshots
The creation of snapshots is really simple - one command is enough. Using the list command snapshots can be displayed including their size:
1# ssm snapshot -s 1G -n crash_snap lvm_pool/crash_vol
2# ssm list snap
3-----------------------------------------------------------------
4Snapshot Origin Volume size Size Type
5-----------------------------------------------------------------
6/dev/lvm_pool/crash_snap crash_vol 1.00 GB 0.00 KB linear
7-----------------------------------------------------------------
8
9# dd if=/dev/zero of=/crash/bla.bin bs=1024k count=10
10# ssm list snap
11-------------------------------------------------------------------
12Snapshot Origin Volume size Size Type
13-------------------------------------------------------------------
14/dev/lvm_pool/crash_snap crash_vol 1.00 GB 10.04 MB linear
15-------------------------------------------------------------------
Snapshots are deleted like volumes:
1# umount /crash
2# ssm remove lvm_pool/crash_snap
3# mount /dev/lvm_pool/crash_vol /crash
Currently there is no possibility to recover LVM snapshots - for this you'll have to use lvconvert instead (like before):
1# lvconvert --merge lvm_pool/crash_snap
Expand and check volumes
Expanding LVM volume groups and logical volumes is simpler using the SSM than applying well-known lvresize/resize2fs commands:
1# ssm add -p lvm_pool /dev/sdc
2 No physical volume label read from /dev/sdc
3 Physical volume "/dev/sdc" successfully created
4 Volume group "lvm_pool" successfully extended
5# ssm resize -s 10G lvm_pool/crash_vol
6# ssm list pool
7----------------------------------------------------
8Pool Type Devices Free Used Total
9----------------------------------------------------
10fedora lvm 1 0.00 KB 19.51 GB 19.51 GB
11lvm_pool lvm 2 4.99 GB 15.00 GB 19.99 GB
12----------------------------------------------------
13
14# ssm check lvm_pool/crash_vol
15Checking ext4 file system on '/dev/mapper/lvm_pool-crash_vol':
16Device '/dev/mapper/lvm_pool-crash_vol' is mounted on '/crash' Unmount (N/y/q) ? Y
17e2fsck 1.42.5 (29-Jul-2012)
18...
19/dev/mapper/lvm_pool-crash_vol: 12/655360 Dateien (0.0% nicht zusammenhängend), 61231/2621440 Blöcke
20OK
Conclusion
For an administrator SSM is a very interesting tool which is able to handle a lot of features and functions by now. I'm missing some things to call the SSM a perfect tool - including:
- creation of LVM volume groups without logical volumes
- recovering LVM snapshots
- print internally executed LVM/*2fs commands for documentation purposes
I'm really exited in seeing the further development progress of SSM. For the next RHEL release 7.0 the new tool is a bleeding-edge "enhancement candidate".