Re: New feature: Migrate active filesystems for I/O load balancing

So far looking good.  Below I demonstrate the procedure to properly
migrate a hard mount from node 1 to 2.

Some information:
- Filesystem migration only supports hard mounts.
- New nodes that join the cluster during migration do see the "down"
hard mount and will be able to access the mount after the filesystem
has migrated.
- Same with failover, migration speed depends on how fast fsck
completes and on a journaling filesystem it is very quick.
- High availability is not affected and as usual the hard mount
survives single and/or multiple node failure(s) anytime during,
before, or after migration.

Roger

[root@node1 linux]# mount /misc
[root@node1 linux]# onall cat /proc/mounts
(node 1)
rootfs / rootfs rw 0 0
/dev/root / cfs rw,node=1 0 0
none /cluster/node1/dev tmpfs rw 0 0
/proc /proc proc rw,nodiratime 0 0
/sys /sys sysfs rw 0 0
none /cluster/node1/dev cfs rw,node=1 0 0
none /cluster/dev/pts devpts rw 0 0
/dev/sda1 /boot cfs rw,node=1 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
0000002e /cluster/node2/dev cfs rw,node=2 0 0
/dev/sdb1 /misc cfs rw,chard,node=1 0 0  <<<<<<<<<<<
(node 2)
rootfs / rootfs rw 0 0
00000022 / cfs rw,node=1 0 0
none /cluster/node2/dev cfs rw,node=2 0 0
00000026 /cluster/node1/dev cfs rw,node=1 0 0
/proc /proc proc rw,nodiratime 0 0
none /cluster/dev/pts devpts rw 0 0
00000029 /boot cfs rw,node=1 0 0
/sys /sys sysfs rw 0 0
0000002b /misc cfs rw,chard,node=1 0 0  <<<<<<<<<<<
[root@node1 linux]# umount -n -l /misc
[root@node1 linux]# onall cat /proc/mounts
(node 1)
rootfs / rootfs rw 0 0
/dev/root / cfs rw,node=1 0 0
none /cluster/node1/dev tmpfs rw 0 0
/proc /proc proc rw,nodiratime 0 0
/sys /sys sysfs rw 0 0
none /cluster/node1/dev cfs rw,node=1 0 0
none /cluster/dev/pts devpts rw 0 0
/dev/sda1 /boot cfs rw,node=1 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
0000002e /cluster/node2/dev cfs rw,node=2 0 0
0000002b /misc cfs rw,down,chard,node=1048577 0 0  <<<<<<<<<<<
(node 2)
rootfs / rootfs rw 0 0
00000022 / cfs rw,node=1 0 0
none /cluster/node2/dev cfs rw,node=2 0 0
00000026 /cluster/node1/dev cfs rw,node=1 0 0
/proc /proc proc rw,nodiratime 0 0
none /cluster/dev/pts devpts rw 0 0
00000029 /boot cfs rw,node=1 0 0
/sys /sys sysfs rw 0 0
0000002b /misc cfs rw,down,chard,node=1 0 0  <<<<<<<<<<<
[root@node1 linux]# onnode 2 fsck /misc
fsck 1.38 (30-Jun-2005)
e2fsck 1.38 (30-Jun-2005)
/dev/sdb1: clean, 15/26104 files, 8967/104388 blocks
[root@node1 linux]# onnode 2 mount -o remount /misc
[root@node1 linux]# onall cat /proc/mounts
(node 1)
rootfs / rootfs rw 0 0
/dev/root / cfs rw,node=1 0 0
none /cluster/node1/dev tmpfs rw 0 0
/proc /proc proc rw,nodiratime 0 0
/sys /sys sysfs rw 0 0
none /cluster/node1/dev cfs rw,node=1 0 0
none /cluster/dev/pts devpts rw 0 0
/dev/sda1 /boot cfs rw,node=1 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
0000002e /cluster/node2/dev cfs rw,node=2 0 0
0000002b /misc cfs rw,chard,node=2 0 0  <<<<<<<<<<<
(node 2)
rootfs / rootfs rw 0 0
00000022 / cfs rw,node=1 0 0
none /cluster/node2/dev cfs rw,node=2 0 0
00000026 /cluster/node1/dev cfs rw,node=1 0 0
/proc /proc proc rw,nodiratime 0 0
none /cluster/dev/pts devpts rw 0 0
00000029 /boot cfs rw,node=1 0 0
/sys /sys sysfs rw 0 0
/dev/sdb1 /misc cfs rw,chard,node=2 0 0  <<<<<<<<<<<


On Nov 13, 2007 4:38 AM, Roger Tsang <[email protected]> wrote:
> Hi,
>
> I added some code to enable migration of active filesystems for load
> balancing.  This is a brand new feature (was in the specs but never
> coded).  It is compatible with DRBD-SSI and of course with shared
> storage.  With this feature OpenSSI has the ability to move individual
> filesystem mounts from node to node at anytime without taking down any
> nodes and without stopping any clusterwide processes using that
> filesystem.
>
> Depending on how the testing goes we could see this included in the
> coming release.
>
> -Roger
>

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