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We are building up some new servers and want to use 12Gbps SAS3 drives alongside some SATA 6Gbps Enterprise SSD's attached to a single Supermicro SAS3 backplane using an LSI SAS3 Expander and LSI / Broadcom 9361-8i RAID Controller with CacheCade Pro 2.0.

RAID Config will be as follows

  • Array 1: 2 x SATA3 SSDs RAID1
  • Array 2: 2 x SATA3 SSDs RAID1
  • Array 3: 6 x SAS3 HDDs RAID10
  • CacheCade Pro 2.0 attached to Array 3: 2 x SATA3 SSDs

Question 1: Will 12Gbps and 6Gbps drives play nicely on the same 12gpbs expander and controller without compromising performance?

Question 2: Should I use interposers on the SATA3 SSDs to achieve the RAID config outlined above?

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Will 12Gbps and 6Gbps drives play nicely on the same 12gpbs expander and controller

Yes

without compromising performance?

No, the 12Gbps SAS drives will drop down to 6Gbps.

Should I use interposers on the SATA3 SSDs to achieve the RAID config outlined above?

Not in my mind no, they add a great deal of additional 'moving parts' that could easily break and cause you data issues. That said I also don't like mixing SATA and SAS together, especially not on the same bus/expander. I'd be very much tempted to either run each type on separate, and separately-cabled, expanders or if that's not possible internally to buy an external shelf and run on type of disk on that.

  • 12Gbps drives will be pulled down to 6gbps, only if the drives are in the same array. If like drives are kept in the same array they will perform at their specification – ausip Mar 8 '17 at 21:33
  • Incorrect, it's about the bus and expanders used, nothing to do with which array they're in. – Chopper3 Mar 9 '17 at 7:29
  • my above answer was referencing the information given in the original question, where the expander and bus where said to be 12Gbps (SAS3). – ausip Mar 9 '17 at 10:28
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Direct from Broadcom / LSI Tech Support. Great support and very fast response to my pre-sales reqeuest.

CacheCade will not work with 4k native sector drives but it will work with 512e and 512b LBA.

That set aside, yes 12 gig and 6gig/sec drives will work fine together as long as they are in their own array.

Is the backplane capable of SATA and SAS? If so, then you do not need interposers.

Some SuperMicro chassis cannot physically accept SATA drives in which case you would probably need an interposer.

Thank you,
LSI Storage Technical support
Broadcom ltd.

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