topic Re: VG7100 Active Spare in Disk Enclosures

VG7100 Active Spare

Linda Cooper — Fri, 27 Feb 2004 15:55:15 GMT

I only have one active spare on my array. I was told this was not enough, that they had seen 2 drives go down at once. How many do most of you have?

Re: VG7100 Active Spare

Navid HUSSAIN_2 — Sat, 28 Feb 2004 01:16:13 GMT

Hi,

It is rare that 2 drives go down at once, If you really want to have more redundancy, then you may go for 2DP.

Thx

NH

Re: VG7100 Active Spare

Uwe Zessin — Sat, 28 Feb 2004 07:44:13 GMT

I thought I had read that the VA7100 (I guess VG7100 is a typo) does not support AUTORAID? Has that changed?

Re: VG7100 Active Spare

Linda Cooper — Sun, 29 Feb 2004 13:21:49 GMT

You are correct that is a typo should be VA7100

Re: VG7100 Active Spare

Arend Lensen — Mon, 01 Mar 2004 05:29:26 GMT

Hello Linda,
The VA will have 1 disk hotspare per RG when the number of disks in a RG are 15 or less. As soon as you add the 16th disk it will use 2, this is what happens when hotspare is set to auto, you can also select 1 or 2 disks manually if you like.

Regards,
Arend

Re: VG7100 Active Spare

Arend Lensen — Mon, 01 Mar 2004 05:31:49 GMT

Forget to mention that the largest disk(s) will be used for hotspare size. And ALL VA arrays support raid-01 and autoraid mode.

Re: VG7100 Active Spare

Joshua Scott — Mon, 01 Mar 2004 14:22:18 GMT

2 drives may fail within a short time, but never "at once". if you have an active hot spare, then 2 drives may fail without any loss of data.

it works like this:

you have a drive fail, and the AHS takes over for it seamlessly, then if you have another failure, you simply have no redundancy. no data-loss. if you are operating in AUTORaid mode, then you can lose even more. you will just sacrifice performance as you go.

For *true* redundancy, you need the VA7110, which has 2 redundancy groups.

Josh

Re: VG7100 Active Spare

Uwe Zessin — Mon, 01 Mar 2004 15:01:38 GMT

I don't understand - the two redundany groups just split the disks, well, into 2 groups. A LUN is always made from disks of one RG at a time.

Re: VG7100 Active Spare

Joshua Scott — Mon, 01 Mar 2004 15:09:33 GMT

Uwe,

yes, but with 2 RG, you are less likely to lose data with multiple drive failures.

Josh

Re: VG7100 Active Spare

Uwe Zessin — Mon, 01 Mar 2004 15:13:30 GMT

I see, you hope that multiple disk failures are distributed equally between both RGs - don't ever let Murphy hear about this ;-)

I was puzzled, because you wrote:
"For *true* redundancy, you need the"
and thought you meant some form of redundany distributed over both RGs.

Re: VG7100 Active Spare

Joshua Scott — Mon, 01 Mar 2004 15:16:53 GMT

I misspoke. for true redundancy, you would need 2 VA7110s connected to 2 servers in a MC/SG configuration, with mirroring between the 2 VAs.

Josh