Mixing SAS and SATA drives on a new SAS backplane
Posted on 2014-09-22
I need some advice to pick the best option.
I bought a barebones supermicro server with a LSI megaraid 9361-8i raid controller with write back cache, which tolerates SAS or SATA drives. It has 2 mini SAS ports internally that are connected with mini SAS 1 to 4 cables to the backplane (Supermicro SAS743TQ for an 8 drive enclosure), but the backplane's documentation states all drives should be either SAS or SATA. Is that really true?
My plan was to have 3 SATA Intel s3700 SSDs (raid 1 with hot spare for OS and applications) with 5 SAS WD 4TB HDDs (raid 10 with hot spare for archival data). I have the drives.
Option 1- Connect drives as planned to the backplane. Why should they not be mixed if raid controller allows both? I am not extending the backplane and there is no logic done there to my little knowledge, so I don't understand the warning from Supermicro about not mixing drives on the backplane. The Intel SSDs are enterprise level drives, the best I could afford, and I'm not aware of any better.
Option 2- Use a mini SAS 1 to 4 SATA adapter to connect the raid controller to the SSDs, bypassing the backplane for the SSD drives. I would have to take the hot spare away from the archival data array, not a big loss, as I would be limited to 4 SAS drives. My problem is putting the SSDs securely in the LFF enclosure as the 3.5" to 2.5" adapter is meant to position it properly for the backplane. Is there a universal adapter that holds a sff drive away from the backplane? Thought I'd ask here before trying with supermicro.
Option 3- Use software raid for my SSDs and the expensive LSI controller just for the SAS drives. My motherboard has 10 SATA ports, 2 peach and 8 white (not sure what that means). Anyway, same problem as in Option 2 that I won't be able to use the spiffy 3.5" to 2.5" drive adapters since they push the drive onto the backplane, so either a different adapter or the SSDs don't go in the drive enclosure and I don't get the little lights to watch for functioning drives.
Option 4- Replace the SAS 4 TB HDDs with SATA 4 TB HDDs. What I get for buying them already, but I have always used SAS drives in servers.
Option 5- Something you would recommend other than the above.
Appreciate your advice. Seems there a lot of people mixing SSDs and HDDs, so I'm hoping mixing SAS and SATA on a backplane is a known issue.