SAS Ports

[bigdogchris]

I've got an older 36 bay Super Micro server with a 2 port 6Gb SAS RAID card. Super Micro has 24 drives on one port and 12 drives on the other due to how the backplane is set up (24 drives up front 12 in the rear).

If I have 6Gb of bandwidth to 24 drives and 6Gb to 12 drives, to me, that sounds like a bad design. Am I misunderstanding how the bandwidth is distributed to the drives?

https://www.supermicro.com/products/system/4u/6047/ssg-6047r-e1r36n.cfm

 

[mwroobel]

I've got an older 36 bay Super Micro server with a 2 port 6Gb SAS RAID card. Super Micro has 24 drives on one port and 12 drives on the other due to how the backplane is set up (24 drives up front 12 in the rear).

If I have 6Gb of bandwidth to 24 drives and 6Gb to 12 drives, to me, that sounds like a bad design. Am I misunderstanding how the bandwidth is distributed to the drives?

https://www.supermicro.com/products/system/4u/6047/ssg-6047r-e1r36n.cfm

1 SAS multilane cable contains 4 6Gb lanes, yielding almost 2.4GB/s of theoretical bandwith. If you are using SSD's only, you should be on SAS12 or NVME and not using this enclosure. For the workload and the SAS2/SATA3 spinning drives it was designed for, you generally won't notice a difference.

 

[bigdogchris]

1 SAS multilane cable contains 4 6Gb lanes, yielding almost 2.4GB/s of theoretical bandwith. If you are using SSD's only, you should be on SAS12 or NVME and not using this enclosure. For the workload and the SAS2/SATA3 spinning drives it was designed for, you generally won't notice a difference.

Yeah, it's all spinners.

 

[Blue Fox]

You'll have no bandwidth issues with hard drives. For maximum bandwidth, run 2 cables from your HBA to the 24 port backplane and then another cable between the two backplanes. That will get you 4.8GB/s to the front 24 drives and 2.4GB/s to the rear 12 (albeit shared).

 

[sinisterDei]

Listen to this fella - Blue Fox - he Supermicros. For seriously I mean.