[SOLVED] Slow Parity Checks

[expressexcess]

Hi there,

 

I am wondering if anyone can shed any light on my experience with slow parity checks. With a 6 TB parity disk, I am experiencing parity checks of ~25-35 MB/Sec. I let the parity check run for 6 hours and it only completed 10%

 

Setup:

 

Motherboard -ASRock Fatal1ty X99M Killer

RAM - 2x8GB Crucial DDR4 (ECC) - CT8G4RFS4213

SATA card - Supermicro AOC-SAS2LP-MV8

CPU - Xeon E5-1650 v3

PSU - Seasonic Platinum Series X-860

 

Drives

Currently, there are 5 data+parity drives in the server all connected in the same 5 bay enclosure. The parity drive and 3 data drives are 6 TB WD Red Drives. The last data drive is a 3 TB WD Red Drive. All of the drives are formatted as XFS. The data allocation on the drives is between ~ 20 GB on the 3 TB to ~ 5.1 TB on the most full 6 TB.

 

The parity drive is connected directly to a SATA Port on the motherboard, while the data drives are each connected to a single port on the AOC-SAS2LP-MV8 card.

 

I have 2x 512 GB SSDs that are used in a cache pool, connected to SATA ports directly on the motherboard.

 

Troubleshooting

 

I mounted each data disk as a disk share, and copied the same 8 GB file directly to the share. The write speeds that I saw were between 50-100 MB/sec. I then copied that 8 GB file from each data disk and saw sustained read speeds between 100-135 MB/sec.

 

I disabled all dockers and ensured that there are no open streams but still achieve the same parity check speeds. I manually forced the mover and verified that there was no data that needed to me relocated from my cache drives.

 

I've attached a syslog, can anyone provide any guidance or further troubleshooting steps? Could the server be having issues fully spinning all 5 disks up at the same time? If the drives aren't getting sufficient power could this cause them to work but at slower speeds?

 

Thank you,

Greg

syslog.zip

[pkn]

I've encountered similar problem.

[expressexcess]

D'oh! Time for me to hang my head in shame.

 

It looks like my issue was caused by the PCI slot I was using for my SATA card. I never noticed, but now realize that in my previous configuration the card was being used at 4x. During my troubleshooting with my PCI passthrough for my VM, I switched my PCI slots and the card is being utilized at 8x. My parity check is currently running at ~140-150 MB/s.

 

Good luck with your issue pkn, I hope you find a resolution!