Dm-multipath-vscsi
From Linux on Power wiki
Using dm-multipath (no success...)
- 1. Check minor/major numbers:
op720-1-client1:~ # ls -al /dev/sdd brw-rw---- 1 root disk 8, 48 Jan 11 08:47 /dev/sdd op720-1-client1:~ # ls -al /dev/sdc brw-rw---- 1 root disk 8, 32 Jan 11 08:47 /dev/sdc
- 2. Check disk size
op720-1-client1:~ # dmesg |grep 512-byte SCSI device sdc: 20971520 512-byte hdwr sectors (10737 MB) SCSI device sdd: 20971520 512-byte hdwr sectors (10737 MB)
- 3. Create response file for dmsetup
op720-1-client1:~ # cat dmtest.txt 0 20971520 multipath 0 0 2 1 round-robin 0 1 1 8:32 1000 round-robin 0 1 1 8:48 1000
- 4. Setup dm-devices
op720-1-client1:~ # dmsetup create dmtest dmtest.txt
- 5. Multipath
op720-1-client1:~ # multipath -ll dm names N dm table dmtest N dm table dmtest N dm status dmtest N dm info dmtest O dmtest [size=10 GB][features="0"][hwhandler="0"] \_ round-robin 0 [active] \_ #:#:#:# sdc 8:32 [active][faulty] \_ round-robin 0 [enabled] \_ #:#:#:# sdd 8:48 [active][faulty]
-> No idea how to get it ready instead of faulty
op720-1-client1:~ # dmsetup info Name: dmtest State: ACTIVE Tables present: LIVE Open count: 0 Event number: 0 Major, minor: 253, 0 Number of targets: 1
op720-1-client1:~ # dmsetup table dmtest 0 20971520 multipath 0 0 2 1 round-robin 0 1 1 8:32 1000 round-robin 0 1 1 8:48 1000
- 6. Trying to use dm-device
p720-1-client1:~ # fdisk -l /dev/dm-0 Disk /dev/dm-0: 10.7 GB, 10737418240 bytes 255 heads, 63 sectors/track, 1305 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk /dev/dm-0 doesn't contain a valid partition table
Formatting and mounting it
op720-1-client1:~ # mkfs.ext3 /dev/dm-0
mke2fs 1.38 (30-Jun-2005)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
1310720 inodes, 2621440 blocks
131072 blocks (5.00%) reserved for the super user
First data block=0
80 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 35 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
mount /dev/dm-0 /mnt tar clvf /mnt/test.tar /
op720-1-client1:~ # df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 16G 1.5G 15G 10% / tmpfs 491M 8.0K 491M 1% /dev/shm /dev/dm-0 9.9G 964M 8.5G 11% /mnt
- 7. Failure test
If VIO1 is going down and /dev/sdc is not available: system crashes
- XX. Remove dm-Device
op720-1-client1:~ # dmsetup remove dmtest
Using md-device (works)
- 1. Create md-devise /dev/md0 with multipath level using /dev/sdd and /dev/sdc (given sdd and sdc are one and the same lun exported through two VIO servers)
op720-1-client1:~ # mdadm --create /dev/md0 -l multipath --raid-devices 2 /dev/sdd /dev/sdc
- 2. Check status
op720-1-client1:~ # cat /proc/mdstat
Personalities : [multipath]
md0 : active multipath sdc[1] sdd[0]
10485696 blocks [2/2] [UU]
unused devices: <none>
from /var/log/messages:
Jan 12 09:41:58 op720-1-client1 kernel: md: bind<sdd> Jan 12 09:41:58 op720-1-client1 kernel: md: bind<sdc> Jan 12 09:41:58 op720-1-client1 kernel: md: multipath personality registered as nr 7 Jan 12 09:41:58 op720-1-client1 kernel: multipath: array md0 active with 2 out of 2 IO paths
- 3. Format and mount it
mkfs.ext3 /dev/md0 mount /dev/md0 /mnt
- 4. Failover (shutting down VIO2 providing /dev/sdd)
op720-1-client1:~ # cat /proc/mdstat
Personalities : [multipath]
md0 : active multipath sdc[1] sdd[2](F)
10485696 blocks [2/1] [_U]
unused devices: <none>
- 5. Readding device
op720-1-client1:~ # mdadm -r /dev/md0 /dev/sdd mdadm: hot removed /dev/sdd op720-1-client1:~ # mdadm -a /dev/md0 /dev/sdd mdadm: hot added /dev/sdd
op720-1-client1:~ # cat /proc/mdstat
Personalities : [multipath]
md0 : active multipath sdd[2] sdc[1]
10485696 blocks [2/1] [_U]
unused devices: <none>
