Exporting physical disk to ldom or ZFS volume

UNIX Solaris
1

Generally, this is what we do:-

  1. On primary, export 2 LUNs (add-vdsdev).
  2. On primary, assign these disks to the ldom in question (add-vdisk).
  3. On ldom, created mirrored zpool from these two disks.

On one server (which is older) we have:-

  1. On primary, create mirrored zpool from the two LUNs.
  2. On primary, assign this zfs disk to the ldom in question (add-vdisk).
  3. On ldom, create single disk zpool from this.

On this one server we're getting performance issues. I've heard that doing it this way (i.e. mirrored zfs on primary and exporting this) is not the best way to do it and will create an overhead?

Is this true? Or doesn't it make any difference?

2

In the second example, are you using ZVOLs ?

Using zvols is not so good performance wise.
You are adding additional layers without need.

If not, can you explain with a bit more detail how are you exporting mirrored zpool from primary to ldom ?

In the first example, you are doing things properly.

An output of the following commands would be useful :

ldm list -l <slow_perf_ldom>
ldm list-services
1 Like
3

Yes ZVOLS....

We've managed to get rid of this now. Heres what we did:-

  1. Added new LUN as vdisk to existing (exported zvol) on ldom as a mirrored disk. (Took a LONG time to resilver - which shows how slow the disk is).

  2. Added another LUN as vdisk to create 3 way mirror (this was faster).

  3. Dropped the old zvol from the mirror.

Performance is now MASSIVELY much faster.

Understand its not ideal to use the zvol but I can't see anything in manual which says its this bad.

4

It's not inherently bad, just slower.
And adding additional layer will cause you more prone to bugs.
Which exist for zvol performance.
It has its uses, but probably not for scenario you are in.

Keep it simple and closest to hardware you can get.

Question is, what is that ldom being used for and what release are you running ?

Regards
Peasant.

1 Like
5

Solaris 10 ldom version 2.2 for the control domain.
Probably should upgrade to Solaris 11.3 I guess.

The ldom in question is also Solaris 10. There may be an application reason for this.

Its a web server mainly though running apache (there are two servers load balanced)