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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?
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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

  • Very rare, got these on Adaptec 7 series controllers. Afaik only Areca, Adaptec and Adaptec-based HP's support this. – GioMac Sep 18 '13 at 12:42
  • @GioMac Which HP adapter is Adaptec-based? – ewwhite Sep 18 '13 at 12:43
  • investor.pmcs.com/… – GioMac Sep 18 '13 at 12:46
  • All newer adapters will be PMC-based, no more LSI – GioMac Sep 18 '13 at 12:46
  • BTW, connectors are very tight because of density and in case of angled ones It's practically impossible to use nearby slots - they occupy the space and there's nothing you can do - they aren't flexible. Also, 1/3 of cables I've bought were problematic - poor contact. – GioMac Sep 18 '13 at 12:50
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Judging by pictures and cable offerings, they are physically different but electrically compatible - vendors sell SFF-8643 to SFF-8087 cables. So you are looking at purchasing new cables with them, like the one half way down this page (no affiliation or recommendation, just the first I came across).

SFF-8643 SFF-8087

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