In the office, we've elected to whitebox go with a commodity approach to a certain class of server we'll eventually need a lot of. It's time to consider picking up a few more. It has been a year since the last time we did this, so I'm looking to update a few components.
Specifically, the RAID card.
When we built these the first time around, we used the Adaptec 6805 card which uses SFF-8087 cables internally. This was fine, since the chassis they were going into also had that kind of socket. Worked great, nice big brick, haven't had a problem with them ever.
I see their 7x and 8x series are out now, but they're using SFF-8643. The 7x series is the same 6Gb SAS as the 6x series, but they're using the 12Gb/s cable for some reason.
I'm not thinking of the 8x series since I can't do 12Gb SAS yet, but the 7x series is a possibility. However, it uses a different cable.
- Are SFF-8643 cables like USB3 cables vs USB2 in that they're backwards compatible to the lower spec?
- Are SFF-8643 cables more like OM3 cables vs OM2, in that they're the same cable just made to a higher spec (and thus compatable)?
- Or are SFF-8643 cables electrically and pinned differently so they're Not At All The Same Thing?
Best Answer
Good question. I'd never even seen an SFF-8643/SFF-8644 connector before. It's not even on the Serial-Attached-SCSI Wikipedia page (yet)!!
So, as with all things, throwing parts into a chassis and calling it a server is fraught with peril... But you understand those risks :) Your RAID controller selection should be driven by features, requirements and possibly your backplane (and backplane connectors). You can obtain an SFF-8643->SFF-8087 cable, for instance.
The SAS protocol is backwards compatible, so that won't be an issue. I'd make sure your drives are 6Gbps, though. The key is finding the right cable to match your drive backplane and controller. There's actually a dedicated site outlining SAS SFF-8643 compatibility: http://www.sff8643.com