LVM Striping of LUSE's (Pro's / Con's)

[Dan Hoyt]

Would I see a benefit if I did LVM striping across LUSE's?

I just created 10 OPEN-E*3 LUSE's (Made up of expanded dispersed OPEN-E's spread across 3 parity groups), and thought I might get better performance if I stripe them at the LVM.

XP512

Any input conserning question is welcome.

Thanks,
Dan

[Patrick Wallek]

If you have multiple fibre controllers going to the switch and multiple connections to the array then yes, you might see some improved performance by striping. You must make sure that you stripe across the controllers to get maximum benefit.

[Steven E. Protter]

In general, more spindles means better performance on the logical volumes.

This kind of depends on the setu of the LUSE's.

If they are all LUN's on single disk's you get to essentially strip across 10 disks. If each of those LUSE's are already striped across a bunch of disks there is no performance advantage from this setup.

Striping has some issues. It can slow down writes because the data needs to be updated in more places. That's my simplistic interpretation of Keeenan's discussion in HP CSE Guide.

Also, Oracle and many other database vendors recommend Raid 1 or Raid 10 for data, index and other high performance objects. Any variation of Raid 5 striping is going to hinder the performance of these applications.

In general, Keenen recommends hardware solutions versus software solutions. He contends (and he seems a very competant admin) that software striping and raid is an inferior alternative to hardware solutions. It uses cpu cycles that might be needed elsewhere.

So You might be better off without LVM striping.

If you have time, perhaps runs some tests both ways and use actual data to make your decision.

SEP

[Dan Hoyt]

Our XP512 is set up using Raid 5 3+1 and my LUSE's are made up of OPEN-E*3 disks across 3 different parity groups.

I may introduce even more problems if I do this since I only have the three parity groups that are each made up of the same 4 disks (2-2 DDDP 2-3 DDDP 2-4 DDDP) and If I stripe them together I may get poorer performance since it may be trying to beat up the same physical disk.

Any thoughts to that??????

[Patrick Wallek]

Dan,

That is very true. If all LUSEs are spread across the same disks then you could cause problems with LVM striping AND XP512 striping.

In that case I would not use LVM striping, but use another controller for the alternate links to the disks (pvlinks) to allow higher availability.

[Dan Hoyt]

Thanks for your help