topic Re: getting VA7100 to do RAID 10 in Disk Enclosures

getting VA7100 to do RAID 10

James Sohr_2 — Thu, 29 Apr 2004 16:46:26 GMT

We recently purchased a VA7100 to connect to our N-Class HP9000.

I added several LUNs to the array using CommandView, but I don't see any option to force the LUN to use particular drives... nor are there any options to force it to use RAID 10 instead of AutoRaid.

I RTFM, and according to it I have to issue an
'armmgr -C raid10 /path/to/device', but when I do, I get an "Box Level RAID is not supported by this Array."

Any ideas? I would like to setup the LUNs and specify which physical drives they are to be associate with, as well as specify the raid levels. Is this possible?

THanks,
James

Re: getting VA7100 to do RAID 10

Bernhard Mueller — Fri, 30 Apr 2004 03:26:24 GMT

James,

you cannot specify which LUN uses which drives. *All* LUNs in a VA use *all* available disks in the Redundancy Group (the 7100 has only one RG), to optimize performance an flexibility.

You *could* change the setting from "raid1+0" to "hpautoraid", but you cannot do the reverse (even if you knew you had enough free space on your disks). Even for a change to autoraid a *full backup* is recommended!

Actually you do not have to explicitly set raid1+0, as long as you leave enough space available (i.e. do not assign more than about 50% of gross capacity to LUNs, the VA will always use raid1+0. It only moves the least used blocks to RAID5DP *IF* you request to assign more LUN space.

So don't touch the setting, rather add disks if you have slots available. Which will also improve performance (see above)

Regards,
Bernhard

Re: getting VA7100 to do RAID 10

James Sohr_2 — Fri, 30 Apr 2004 10:47:55 GMT

Thanks!

So, if I have 12 36GB drives, I should only create 12*36/2 = 216 GB worth of LUNs or less to get it to do RAID 1+0?

If I can't specify which LUNs use which drives (I suppose all LUNs use all drives?), is there any performance benefit to creating more than one LUN? We have one busy database, and I would've like to isolate that to it its own set of drives...

Re: getting VA7100 to do RAID 10

Patrick Wallek — Fri, 30 Apr 2004 13:25:57 GMT

There is a tool that I happen to have (no questions please!!!) that will allow you to calculate the different capacities on the different VA* arrays.

With a VA7100, with 12 x 36 GB drives, with Active Hot Spare set to AUTO and in RAID 1+0 mode, you have a maximum amount of usable space of 196.8 GB.

Since you are in AUTORAID mode, I would think that if you keep your total space allocated to LUNs below 196.8 GB everything should stay in RAID 1+0.

In doing the calculations you have to remember that you will NOT get the full 36GB out of each disk.

Re: getting VA7100 to do RAID 10

Patrick Wallek — Fri, 30 Apr 2004 13:26:59 GMT

Also, you can not specify which drives to use. The data will be striped across ALL drives in the array.

Re: getting VA7100 to do RAID 10

James Sohr_2 — Fri, 30 Apr 2004 13:53:24 GMT

Thanks, Patrick.

So is there any performance benefit to using multiple LUNs instead of one big LUN?

From what I understand, it's not possible to create two LUNs and put each one on a seperate primary controller... correct?

Re: getting VA7100 to do RAID 10

Naveej.K.A — Fri, 30 Apr 2004 21:27:50 GMT

Hi james,

VA7100 has only one RG and one controller. so you can't set up multiple performance paths.

regds
Naveej

Re: getting VA7100 to do RAID 10

Roger Buckthal_2 — Sun, 02 May 2004 21:52:34 GMT

The actual usable capacity for the VA7100 with 12 36GB disks and HotSpare set to Auto (or 1) is: 276.5GB (Binary, as entered with CommandView), the RAID 1+0 only capacity maximum is: 180GB (Binary)

The VA7100 can demonstrate maximum performance with a single LUN. However not all OSs will by default. If itâ s Windows, you OK. If itâ s HPUX, then you must either increase the default SCSI queue depth to 24 to 36 (for a single LUN and 36 disks), or create 3 or 4 LUNs.

BTW, if decide to create more LUNs, reformat the array and select the whole array to be RAID 1+0, youâ ll get a little more usable capacity. And, you donâ t need to stripe the LUNs, the VA will do this