VA7100 Question

[Amiel Tutolo]

I just had a VA7100 installed with 10 36gb/15k drives, 1gb cache and dual controllers. I noticed when setting up the volume groups that I had a choice of paths (0/2 and 0/5). Is there a performance gain to say telling vg01 to go to 0/2 and vg02 to go to 0/5? or am I losing redundancy? If you need anymore info please let me know. Thanks

[Khalid A. Al-Tayaran · Accepted solution]

Hi,

The second path is for redundancy. You don't have to configure any paths. We have 2 VA7100 and are very fast. The VA uses a mirror+strip technology (called RAID 1+0) or AutoRAID. Data is stripped across multiple disks and mirrored at the same time. So, if any disk crashes the other disks will have the data to re-build that crashed disk.....

Go to hp.com for more info on the VA. Also search this forum with the term VA7100 or VA7400.....

[Eugeny Brychkov]

Khalid is correct. As soon as VA7100 has only one Redundancy Group (you can check it with 'armdsp -a' command output) perfomance - primary path for LUNs within VGs should be set to go through VA controller C1. Alternate path should be set to go through controller C2.
Remember: to have LVM path redundancy you should configure BOTH (or more if available) physical paths for physical volume (disk, LUN etc). If you'll not do it, though system has another hardware path to LUN, it will not use it (because it's not configured and system does not know about this path).
Now your job is to identify which path to use as primary (0/2 or 0/5) which uses C1 VA controller
Eugeny

[Michael Steele_2]

You get better performance by having one lun going through one controller and another lun into the secondary controller, but you lose the redundency.

You will get better performance and space utilization with AutoRAID mode. After starting in Raid 0 and 1 the VA7100 will begin to migrate old unused data to RAID-5, freeing up additional space.

Here are some nice links about it.

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xeb630fe6d0f7d61190050090279cd0f9,00.html

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xeb630fe6d0f7d61190050090279cd0f9,00.html

[Jarle Bjorgeengen]

Hi,

HP VA should not be load balanced I.e. let the secondary path be idle in normal situations and configure the lvm primary path to be the VA primary path (Namely the VA controller which controls the raidgroup you access)

This gives the best performance.

Rgds Jarle