choosing backplane with expander or passthrough?

[koifish59]

I have these two supermicro backplanes available to use:

• BPN-SAS3-836EL1 (16x SAS3 slots with expander chip)
• BPN-SAS-836TQ (16x SAS slots, direct connect, no expander)

I was going to use a HBA flashed to IT with the BPN-SAS-836TQ but after trying to connect all the cables, 16 breakout connections to the backplane is unmanageable. The rat’s nest of cables is clogging all the fans.

Looking to switch to the BPN-SAS3-836EL1 but I’ve never dealt with an expander chip before. Which HBA card is best for this? Use case will be TrueNAS Core as a VM on ESXi host, HBA card will be passthrough from ESXi directly to the VM. 100gb memory allocated to this machine, currently have 4x 18tb in mirror, planning to fill all 16 slots as we expand later. Any recommendations for the most suitable HBA is appreciated!

 

[HoneyBadger]

Whatever LSI HBA you have now is likely fine to support a shelf of spinning disks. IT mode is capable of handling expander chips, and the backplane will negotiate SAS2 just fine as well.

If you want SAS3, the cheaper 9300-8i (or any card that crossflashes to it, like a PERC HBA330/H330) will be fine.

See also "Don't be afraid to be SAS-sy":

Don't be afraid to be SAS-sy ... a primer on basic SAS and SATA

With the introduction of SAS 12Gbps, seems like "it's time" to do a braindump on SAS. Work in progress, as usual. History By the late '90's, SCSI and PATA were the dominant technologies to attach disks. Both were parallel bus multiple drop...

www.truenas.com

 

[artlessknave]

if you can avoid the TQ...avoid the TQ.
2 cables is much nicer to work with than 16.
you would need 2 dual port miniSAS cards to connect the TQ.
an "A" backplane is the nicest of the direct connects. in this example, that would be 4 cables, not 16. would still be 2 SAS cards though.

as honeybadger notes, a 9300 card will get you SAS3, and remove any sign of bottleneck in the expander or SAS card, only the drives themselves would be the limit.
as long as the expander isnt damaged or malfunctioning, a SAS expander with the correct amount of bandwidth is nearly indistinguishable from direct connection

 

[koifish59]

Thanks to both of you! I just purchased the Dell PERC HBA300 that honeybadger recommended.

Since 1 cable is more than enough to handle the bandwidth for 16 drives, would there be any other benefit to having the 2nd cable? Load balancing and redundancy for cables and ports perhaps?

 

[artlessknave]

completion-ism. it's there. why not connect it?

 

[koifish59]

You're right.

I have two legs to get around when only 1 is really needed ;)

 

[artlessknave]

if you were going pass it out of the case for an external enclosure, then sure, only 1 connected at sas3 will be more than enough, but otherwise, it might as well be connected. keep the dust out if nothing else.