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VA7100 - RAID 1/0 or AutoRAID

John Tyler
Advisor

VA7100 - RAID 1/0 or AutoRAID

I am looking for a performance comparison while using VA7100s in RAID1/0 versus AutoRAID.

Though it depends on the application hosted on the VA7100 and configuration, is there any general thumb rule that can be assumed.

I am inclined to use the AutoRAID option to get more diskspace but would go RAID 0/1 if the performance difference is huge and noticeable.

Anyone tried to benchmark VA7100 in both configs?

Any comments welcome.
TIA.
1 REPLY
Vincent Fleming
Honored Contributor

Re: VA7100 - RAID 1/0 or AutoRAID

Hi;

I haven't seen any charts or performance comparisons yet, but I understand that the AutoRAID should be very close in performance to RAID 0/1 in most cases.

The VAs have a hardware assist for the RAID 5DP that makes the RAID 5 nearly as fast as 0/1. Besides that, overall a large portion of your data will still be in RAID 0/1.

For example (using round numbers), you have a VA with 200GB raw. You create two LUNs, 0 & 1, each with 50GB. Since the array would net 100GB using RAID 0/1, there's enough space to make the two LUNs all 0/1. If you allocate another LUN (2) of say 10GB, part of either LUN 0 or 1 would need to be converted to RAID 5DP ( I understand that it can use both RAID levels in the same LUN); but the other need not change from 0/1.

The effect is that LUN 0 would be 0/1, and LUNs 1 & 2 would be at least partially RAID 5. This means that LUN 0 retains all of the performance of the 0/1. For overall performance of all LUNs combined, the results should be close to all 0/1, espically if that hardware assist actually works as well as advertised - but even if it doesn't, your performance shouldn't suffer much.

What works for me is to use the "extra" space you get from using AutoRAID for more mundane things like archiving or lightly used directories. It doesn't seem to impact the performance at all, both because it's hardly used and because the database is still mostly RAID 0/1. All the hotspots of the database should always be 0/1, even if parts need to be RAID 5 for the space.

good luck
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