Poor RAID 1 & 5 Perfomance on P410i Smart Array

[mcoll]

Hey all,

DL585 G7

ESXi 5.5.0

93GB RAID 1 + 1TB RAID 5 on P410i w/ Battery

Transfers to both arrays result in slow write speeds, recently updated firmware and same results.

Any other ideas?

[Anonymous]

How slow is slow, and what discs are you using?

How is cache settings?

Here is my Raid10 on P410 w512cache + battery

[mcoll]

Haven't run benchmarks on host OS due to hpacucli not being to detect my controller (doesn't like kernel >= 3.0). Ran ATTO on a guest OS and results were similar to yours.

Using SAS Disks - cache has write override enabled. I tried playing with the priority but couldn't due to the issue above.

[anthony11]

Does your p410i have a cache module installed?  If so, what size?  RAID5 is always going to be write-poor, that's one reason why cache on the HBA is important (and one reason why I *never* use RAID5).

What version of hpacucli/hpssacli are you using?  You mention ESXi, but you also mention kernel 3.x, so I'm uncertain where you're running hpacucli -- AFAIK it never works from a guest OS, one has to run it from the ESXi shell.

HP not long ago renamed hpacucli to hpssacli.  It works the same way.

I use mostly default settings on my SA HBA's, but do enable predictive spare mode.  I haven't had users complain about write speed, but I mostly don't have I/O hungry applications.

Do you have adequate RAM configured for your VM's so that the guest OS's can do caching?  And enough host RAM that ESXi doesn't have to write to swap files?

[MAHarby]

Hi

I hope it's OK to jump in on this thread as we have a similar issue with 'really' poor write speeds with one of our ML350 G6 servers with a P410i controller. Running ATTO shows a minimum write speed of 72 MB/sec against a read speed of 25791 MB/sec (for 0.5 kb file) to write 106100 MB/sec against read 512525 MB/sec (for 8192 kb file). See attached screen-shot.

Looking in the Array Configuration Utility (More Information) under Array Accelerator (Cache) Ratio it shows 100% Read / 0% Write. Is this an indicator ? I have attached the screen-shot.

We had a drive fail in this array a while ago, however, the RAID 5 array is fully built.

Any help or pointers appreciated.

Mark Harby

Nottingham. UK

[anthony11]

1) Write performance is always going to be limited when using RAID5, one reason I *never* use it.

2) 100/0 is an anomalous write cache setting.  My p410i's default to

   Cache Ratio: 25% Read / 75% Write

   Drive Write Cache: Disabled
   Total Cache Size: 1024 MB

Change that and I think you'll see a world of difference.  Your  cache being only 256MB isn't doing you any favors, but reconfiguring to defaults should help.