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getting VA7100 to do RAID 10

James Sohr_2
Occasional Contributor

getting VA7100 to do RAID 10


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
7 REPLIES
Bernhard Mueller
Honored Contributor

Re: getting VA7100 to do RAID 10

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

James Sohr_2
Occasional Contributor

Re: getting VA7100 to do RAID 10

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...
Patrick Wallek
Honored Contributor

Re: getting VA7100 to do RAID 10

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.

Patrick Wallek
Honored Contributor

Re: getting VA7100 to do RAID 10

Also, you can not specify which drives to use. The data will be striped across ALL drives in the array.
James Sohr_2
Occasional Contributor

Re: getting VA7100 to do RAID 10

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?
Naveej.K.A
Honored Contributor

Re: getting VA7100 to do RAID 10

Hi james,

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

regds
Naveej
practice makes a man perfect!!!
Roger Buckthal_2
Frequent Advisor

Re: getting VA7100 to do RAID 10

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