I have searched around for an answer to this question but have not found one.

 

I have a 4U Norco server with 20 front drive bays. The server is fairly old. Each of 3.5 drives plugs into a SATA port via the backplane which is connected to a SAS card. I think this is fairly standard. Is there a difference in backplane type when it comes to speed or is the bottle neck in my card, cpu or motherboard? in short are there faster backplanes or all pretty equal? I ask because I wonder if people ever replace their backplane for a faster one?

If the backplane doesn't have an expander it's won't make any difference, i.e., if each disks connects to the HBA direclty, with a SAS expander the type of expander (SAS1, 2 or 3) and if it's linked using single or dual channel to the HBA can make a difference.

2 hours ago, johnnie.black said:

If the backplane doesn't have an expander it's won't make any difference, i.e., if each disks connects to the HBA direclty, with a SAS expander the type of expander (SAS1, 2 or 3) and if it's linked using single or dual channel to the HBA can make a difference.

I have a SAS card which uses a SAS cable to plug into the backplane which uses SATA to connect to each of the drives. Based on this it has to have an expander, correct? How can I find out the expander type of my backplane?

 

This is what my system profile says about my SAS card: Serial Attached SCSI controller: Broadcom / LSI SAS2116 PCI-Express Fusion-MPT SAS-2 [Meteor] (rev 02)

AFAIK Norcos don't usually have an expander, a SAS expander allows a single cable from the HBA to connect all disks, can you do that?

13 minutes ago, johnnie.black said:

AFAIK Norcos don't usually have an expander, a SAS expander allows a single cable from the HBA to connect all disks, can you do that?

This is my server chasis. NORCO RPC-4220 4U Rackmount Server Chassis w/ 20 Hot-Swappable SATA/SAS 6G Drive Bays (Mini SAS Connector)

https://www.newegg.com/norco-rpc-4220/p/N82E16811219033?Item=N82E16811219033

 

I am pretty sure (need to open server to verify) that I just have two SAS cables plugged into the backplane from my card.

No expander, each miniSAS plug connects directly to 4 devices.

 

 

Thanks... so in a nutshell I would need to replace backplane or get a new server to increase the speeds.

The backplane you have uses a direct connection the the drives, so no way to be faster, if you have performance issues it's not that, where are you trying to improve perfomance?

When I do a parity check the drives are only reading/writing at about 130MB. It takes about 18 hours to do a parity check. Was hoping to bring this time down to less than half and since I will eventually be building a new server trying to decide what needs upgrading... Should I keep my chasis or get a different one, new HBA card etc.

Please post diags so I can have a look at the hardware you have.

That would be great. See attached.

 

auburn-diagnostics-20200731-1400.zip

You have 3 different disk sizes, parity check can never be faster than the slowest disk at any point, and disks are much slower as they get to the inner cylinders, so it will slow down 3 times, especially noticeable as it gets near the end of the 3TB disks, then 4TB and finally 8TB.

 

Also you have some disks that max out at around 150MB, even on the outer cylinders, like the 4TB Reds, so 130MB/s is not bad, it should be more than that in the beginning but there will be points that it will be much slower, you can get an idea by running the diskspeed docker.

 

Hardware wise your fine, just make sure the HBA is on one of the top 2 slots, the x8 CPU slots, can't see that in the diags.

I would have thought the 4TB reds would be faster. So even if I upgraded the backplane and card it is the disk that is the limitation in my speeds?

 

Thanks for your help.

Most likely the disks, you can compare the diskspeed curve with actual parity check curve using the dynamic stats plugin, like mentioned it can never be faster than the slowest disk, but if slower than that then there could be other issues.