VA7400 Performance

[Eugeny Brychkov]

Fully agree with Vince. Many LUNs, high concurrency. Recommendations:
- tune per LUN queue depth (see my first reply);
- increase LUN PV timeout value in hpux (pvchange -t) to, let's say, 180. At least hosts stop abotring requests;
- make sure you use perfomance paths for LUNs: RG1 LUNs -> VA controller C1, RG2 LUNs -> VA controller C2.
Could you please attach supportshow from both brocades zipped to your next reply (believe they will be under 256K :o) )
Eugeny

[Thomas Maddox]

I tried to state from the beginning of this that I have an over active array. How do I get better performance is my question.

[Eugeny Brychkov]

Thomas, please attach supportshows to check if they're clear.
You can uprade to VA7410, it has more powerful controllers and more cache, twice more frontend and backend ports.
Why did you create so many LUNs (I counted 53). Do you assemble these LUNs into volume groups on LVM level? If yes then I think it would be better to have one big LUN in vg than vg consisting of many little LUNs. This will eliminate high concurrency
Eugeny

[Vincent Fleming]

Thomas,

So, what you are saying is that you cannot purchase any new hardware, and have to make due with what you've got (which happens a lot)...

Don't expect it to double in performance. We may be able to get 10-20% better performance via tuning, but don't expect anything dramatic. I don't think we're going to make all your problems go away.

Now, for some recommendations:

1. Tune your OS' according to Eugeny's suggestions. Queue depth, timout values, etc.
2. If there is any way you can migrate this to RAID 0+1, do it.
Once a VA is in AutoRAID mode, you really need to backup and restore all the data to change to RAID 0+1. Moving to AutoRAID is easy, but the reverse is not true.

3. If you can add more drives to the array, it will help the performance - possibly dramatically. I would add 15 or more 36GB 15K drives.

4. If you can't add more drives, and can't afford the downtime to backup/restore to get to RAID 0+1, then clean up as best you can. The more free space on the array, the more will be RAID 0+1, and not RAID 5 (which is slower than 0+1).

To give you an idea of what I think you need... If I had to make a recommendation for a replacement subsystem for you (which is my day job), I would suggest 2 VA7410's with 45 36GB 15K drives each (minimum), and RAID 0+1. Maybe even an XP array.

Look back for some more recommendations from myself, Euegny, and others.

Vince

[Thomas Maddox]

We will do the following:
Changed queue depth threshold to 72.
Continuing take back and to delete unnecessary LUNS to increase the space for raid 0+1.
Give the array a rest day Saturday to allow it to convert space to raid 0+1.
Set prefetch to on.
Change performance from high to normal.
Continue to monitor performance.

We cannot do the following:
Buy more hardware.
Get the downtime to backup and restore all the data to all the systems on the array.
Stop beating the snot out of the array, because we have an application that is full of snot.
THANKS

[Roger_22 · Accepted solution]

For a 7400 with 45 disks, you'll need to delete LUNs until your RG1 reserved LUN capacity totals less than 795GB, and 700GB for RG2, to make the array run in RAID 1+0. Also, set the array for no hot spares - you really will have them, it will just use RAID 5 space during a disk failure, and convert the data back to RAID 1 once the disk is replaced.

try this, send the output of getvalogs to autoraid@boi.hp.com

[Greg Traud_2]

When I read this thread, it was scary...

Nearly identical hardware setup, and nearly identical problems.

My challenge is that I don't know what is 'optimum', so I can't really tell what our performance is. I just inherited this situation a couple of months ago.

I've spent alot of time collecting megs of stats on the VA7400, but have no 'normal' performance stats to compare them to.

Would someone care to tell me (as simply as you can, please... I'm no whiz at this stuff) what a good baseline would be?