Second Raid array on the same controller?

[milesy]

Hello.

We have a Dell SC1420 sata server. At the moment we have it configured to Raid 1 with the
CERC SATA RAID CONTROLLER 6 CHANNELS. (additional card)
My question is can I connect 2 more drives to the same controller and configure them to Raid 0. So we would have 2 drives running the OS on Raid 1 and 2 drives running Raid 0 for the data.

If it is possible can I do this without disturbing the raid 1 array, or do I ned to start from scratch?

 

[technome]

Unless your adapter work differently then all the raid adapters I have worked with, you can add a raid 0 array, both the raid 1 and raid 0 should live happily together, though with raid 0 I would not expect a long productive life for the raid 0 volume..placing data on a raid 0 is asking for failure. Setting up the raid 0 should not affect the raid 1 array set at all.

........................................
Chernobyl disaster..a must see pictorial

http://www.kiddofspeed.com/default.htm

 

[milesy]

Thanks for that.

When you say "though with raid 0 I would not expect a long productive life for the raid 0 volume" Would you expect problems with raid 0. I have only ever used raid 1 and I just wanted to speed up the main data area that users are accessing. The data is backed up ever night night to tapes and then moved off site for 7 days. So if the data dose go down I can replace it fairly quick.

We are only a small company, We have 2 spare 10,000 RPM SATA drives (Raptor) and I just want to get the most out of what we have without going to raid 5

I would Apprecheate your input on this one.


Thanks

 

[NickFerrar]

Well RAID-0 basically doubles your chance of losing data over a single disk system, or put another way halves the MTBF. As long as you're aware of the risks and don't have the budget for anything else I guess go for it. Personally I'd just have two separate single disk volumes unless you really only want a single logical volume.

 

[jkupski]

Moving your DATA off of the OS volume should help performance in general, but RAID0 is not the way to go about it. As Nick noted, RAID0 is just begging for downtime.

Also, you're not going to gain anything by doing it--your comment that you want to "speed up the main data area that users are accessing" sounds like your bottleneck is in read throughput. In a perfect world, RAID1 and RAID0 have identical read performance. A better bet would be to take those two spare drives and create a second RAID1 volume for data. You obviously lose capacity (n/2 for RAID1 as opposed to n/1 for RAID0) but your volume is 4x as redundant as the RAID0 volume (MTBF doubled vs. halved.)

 

[milesy]

Thanks for all the input.

After listening to all the points I think I am going to scrap the idea of Raid 0 idea and just create a second Raid 1 array for the user data.

Agin many thanks.

 

[milesy]

The controler card let me add the second aray without any problems.