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Is it theoretically possible to mix a SAS2 controller with a SAS expander?

We just happen to have this scenario - the expander (which works fine with an older SAS adaptec controller) is not found and Adaptec (which handle the new 71605Q raid controller) insists on telling me this is because the expander is a SA expander and not a SAS2 expander.

We are in the proces of upgrading our infrastructure - so this test case is not by any means a deaster - but we can not remove certain SAS elements YET (mostly because not everything is available as SAS2 yet).

I was using my google-fu trying to find an answer but I can not find any auhorititative document / description about whether this should work in general.

TomTom
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1 Answers1

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In theory, it is. More specifically, I have had an LSISASx36 (SAS 3G) expander running with an LSI 9200-8e (LSI SAS2008 chip, SAS 6G).

Adaptec of course is free to specify a compatibility list for their RAID controllers and exclude SAS1 expanders, but they explicitly have chosen not to do so - the current compatibility list claims compatibility ("Minimum testing for listed drive enclosures consists of recognition on each RAID controller model and 24 hours of data integrity I/O stress load on each RAID Level under a variety of RAID states") with enclosures containing these SAS1 expander chips:

  • LSI SASX28
  • LSI SASX36 A.0
  • Vitesse VSC7161

(and probably others, check the "Enclosures" section of the compatibility list).

So you definitely should not get this answer from Adaptec support. It is likely that you've got assigned a clueless support agent. Ask for escalation.

the-wabbit
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  • Accepted. Thanks for the links. Turned out the backplane in question was ancient (SAS1, on upgradable firmware) and just had issues - we upgraded. I did not want to ask for a specific question here because I really wanted to know the geneal position but your explanation helped me to get the parties involved - agree where the problem is. THanks a lot. – TomTom Oct 17 '13 at 10:25
  • @TomTom glad it helped. – the-wabbit Oct 17 '13 at 10:32