So I recently purchased this, and am somewhat new to supermicro servers.... Can anyone tell me which backplane would be better? I have the one in the OP, but the A frame one mentioned... would that be better? My intention is freenas + some vm's
2U Supermicro X9DRD-7LN4F-JBOD 12 + 2 Bay Server 1 E5-2620 V2 | eBay
And the RAID controller i'm using for external drives:
Adaptec 78165
I have one of those machines too, and it's nice that you can control 12x HDD with a single SFF-8087 connection. With 4x SAS2 lanes, that's 24Gbps total bandwidth which is quite adequate for many use cases. The 826A backplane would require 3x SFF-8087 connections to manage 12x HDD so it requires more SAS hardware (HBA, RAID, etc.). However, it gives you direct point-to-point connections to each hard drive instead of through a SAS expander; theoretically this should give you more performance capacity if your setup (HDD/SSD and SAS controller) can make use of it. With the fastest HDD maxing out around 200~220MB/sec, 12x gives you 2640MB/sec or about 20.6Gbps so that is still below the 24Gbps of the SAS2 expander backplane. So, it would be very hard to take advantage of the 826A unless you are using SSDs. Other advantages of the 826A backplane are:
- since it is direct connection, your link speed only depends on the end-points. Use a 12Gbps (SAS3) SSD and HBA/RAID controller, and you will link at 12Gbps. With the SAS2 expander, you are limited to SAS2 (6Gbps) speeds. this gives you an upgrade path later on should that matter (mostly if you are using SSDs).
- the "A" backplanes LEDs light up when the hard drives spin up and flicker when there is activity. this makes it very obvious the hard drive is working. with the SAS2 expander backplanes, when using a SATA drive, the LED does not light up, but flickers when there is activity ; this can give the false sense that the HDD isn't working until you see activity on the drive. Using SAS HDDs, the LED lights up when it powers on the HDD, and flickers when there is activity; so the behavior is different based on SATA vs SAS HDD you are using. I've also heard, but haven't verified myself, that with some SATA SSDs, the LED behavior differs too.
