Dual port SAS expanders and SATA drives (SuperMicro "E26")

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sethk

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Hello,

I had a general question for those of you that have experience with higher density storage chassis' with SATA (SSD) drives - I was wondering if there are any known issues using a modern SATA drive with a dual-port SAS (2.0) expander, such as the ones that ship with newer SuperMicro storage enclosures?

I read some older articles about dual port SAS expanders requiring either integrated SATA interposers or using separate interposers for each drive when the interposer is not integrated, to ensure that the drives work properly. Most of this information is pretty old, and I see that SuperMicro no longer sells newer interposers for SATA drives, so I'm wondering if this is still a problem.

I'm planning on using the following chain:

LSI 9285e-8i <-> SuperMicro SC847E26 45bay chassis with integrated dual port SAS 2.0 expander <-> Intel 710 (or Intel 520) SATA drives.

There will also be some Hitachi Ultrastar SAS drives in the enclosure - any thoughts on this setup?
 
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The only *problem* is the expanders to sata drive STP issues.

The biggest issue though, is you remove all redundancy of your setup, cause the sata disk will only be on one backplane, instead of both, without the interposer.

With the price of nearline sas drives currently, I would recommend them, they are only a few dollars more than sata disks.
 
Why would you run a E26 over a E16 chassis ?

It is correct you need a interposer card if you are running multipath on the E26.
 
Would the E26 have an effect on the ability to achieve an x8 wide link between the enclosure and the HBA?

I just ordered an E26 about a week ago, so will be testing this out. It was only about $200 more than the E16 so I went with E26 as in the worst case I figured it would set me up later in a better position if I did start integrating SAS drives into the environment.

I'll be using this enclosure to test an array on 8 Samsung 840 Pro 256G SSDs, btw.
 
I wanted to use the E26 so that I have the option of connecting the chassis to two different boxes, or alternatively, connecting via two different SAS cards. It seems like everyone is pretty sure that the SATA drive is only visible over one of external ports, not over both, which is too bad. From what I read, it is possible to design a SAS backplane with *integrated* interposers, so that you don't need an interposer per drive. I know the last-gen SM backplane didn't have this, but I was hoping that with the upgrade to SAS 2.0 the E26 backplane had integrated interposers for SATA.

As to why choose SATA, it's because even entry-level 'enterprise' SSDs like the Intel 710 are still still SATA only. When reasonably priced SAS SSDs are more common, I will definitely move to that for future storage expansion.

packetboy said:
Would the E26 have an effect on the ability to achieve an x8 wide link between the enclosure and the HBA?

I just ordered an E26 about a week ago, so will be testing this out. It was only about $200 more than the E16 so I went with E26 as in the worst case I figured it would set me up later in a better position if I did start integrating SAS drives into the environment.

I'll be using this enclosure to test an array on 8 Samsung 840 Pro 256G SSDs, btw.
Click to expand...

I don't believe that the E26 reduces the 8x bandwidth, if anything, you may get more bandwidth. I don't have saved links, but going by memory, I have seen some reviews that report higher than 8x bandwidth with SSDs and multiple SAS cards, but it's a little hard to test.
 
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Agreed. Check the price on 2TB SAS drives. That's much more than a few dollars more. The 1TB drives are more reasonable, but still less than some 3TB SATA drives. I may have to go with some interposers, but I still need to figure out if they fit in the SuperMicro cases or not.

Still, that doesn't solve SSD issues. I'm seeing $400-$600 for a Talos C 200GB drive at the moment.
 
I bought the exact same chassis about a year ago and was told by SMC support that a interposer will not fit (not enough clearance for the latch to close on the tray) but ive seen some hacks out on the net to make it work. (unless the chassis has changed) YMMV
 
Current enterprise sata drives vs nearline sas drives are very close in price.

I'm not comparing a wd green/blue/black to a sas drive.

WD 2tb sas, WD2001FYYG $220
WD 2tb re4, WD2003FYYS $200
 
stevebaynet said:
I bought the exact same chassis about a year ago and was told by SMC support that a interposer will not fit (not enough clearance for the latch to close on the tray) but ive seen some hacks out on the net to make it work. (unless the chassis has changed) YMMV
Click to expand...

I only need interposers for SATA SSDs - 2.5 in drives, and those will fit inside the 3.5 in tray I hope. For 3.5 in spinning disk drives the interposer cost is more than the price differential for SAS vs SATA drives in the same product line - e.g. 2tb 7200 hitachi ultra stars or WD RE sas vs SATA.
 
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