topic Re: Using 6 Gbps in a RAID environment with 3 Gbps in Disk Enclosures

Using 6 Gbps in a RAID environment with 3 Gbps

mig1980 — Wed, 21 Nov 2012 20:32:10 GMT

Good day everyone. I have a failed drive on a few of our servers and I was looking at making a purchase. I have 2 servers with RAID 5 and 146 GB SAS drives with 3 Gbps link rate, and I have 2 other servers with 300 GB SAS drives on RAID 5 as well using 6 Gbps link rate.

Could I just purchase 4 300 GB SAS drives using 6 Gbps and use them on all four servers or would RAID be an issue?

I realize that in the 2 servers using 146 GB drives, only 146 GB of the 300 will be utilized.

I understand that the RAID card would have to support mismatched drives but how can I find out if the RAID cards I have do?

I took a look at the RAID cards and two servers have Smart Array P400 cards, another has a P400i and the last has a P410i.

Thank you

Re: Using 6 Gbps in a RAID environment with 3 Gbps

mastsrl — Thu, 22 Nov 2012 12:19:12 GMT

There's no problem using 6gbps drives on a 3gbps backplane/controller, they'll just work at 3Gbps.
the opposite is also true, the controller will just use 3gbps with those drives).

Re: Using 6 Gbps in a RAID environment with 3 Gbps

mig1980 — Thu, 22 Nov 2012 15:15:12 GMT

Is there also no problem using the 300 GB drives in a pool of 146 GB drive RAID 5 array?

Re: Using 6 Gbps in a RAID environment with 3 Gbps

mastsrl — Thu, 22 Nov 2012 15:18:50 GMT

As a replacement for a failed 146GB drive for example?.

no, no problem, but it will only use the smallest common space available, as you have intued it will only use 146GB of that drive(i've done it on RAID1 no problem).

Now the other burning question is: what about when you replace every 146GB drives with 300GB ones in the array if you'd be able to reclaim the lost space, that i have no answer for as i've never tried it myself (and SA controllers tend to ONLY use full drives, so no idea how/if it will allow a capacity expansion WITHIN the same drives)

Re: Using 6 Gbps in a RAID environment with 3 Gbps

mig1980 — Tue, 27 Nov 2012 17:50:12 GMT

I was informed that you could reclaim the lost space once the last drive was replaced with a 300 GB drive as that is an option with the Smart Array controllers. You would need to expand the current LUN or make another one if you choose.