Extremely slow parity sync

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I've just gotten started with unraid in the past few months.  My first server is working great, but the case has no more room drives.  Instead of getting a server case I have no place to mount, I decided to create a second server using an old computer on hand.  I started by installing 10 hard drives salvaged from my old amahi server, which I stopped using.  Drive sizes range from 5 to 8 TB.  I didn't have a parity drive to start, but I recently purchased a 10TB drive to use for parity.  I installed it, assigned it to parity, and the parity sync began.


Unfortunately, the process is proceeding at a snails pace.  Right now the anticipated completion time is 55 days, but I have seen it well over 100 days.  Progress is slow on two fronts.  First, I haven't seen the read speed yet exceed 25 MB/s, but most of the time it is between 1 and 2 MB/s.  As if this weren't bad enough, it only reads for a few seconds before it stops and all drives read 0 MB/s for a few seconds.  This on and off really hurts the average speed. 


This is not a powerful machine, but this is the first time I have had any speed issues.  All drives mechanical (no SSD) and some are connected via SATA II ports, either on the motherboard or pcie cards.  The pcie cards are pcie 2.0 x1, but one has only one port, and the other only two ports so they shouldn't be bottlenecking this bad.  The CPU is only an Athlon X2 270, but according to the dashboard it is barely topping 25% so it doesn't seem like a bottleneck either.


I've attached the system log.  There is an error that keeps repeating on either ATA3.00 or ATA6.00.  I'm guessing this is what's causing my problem.  Can someone please help me identify what the error is.


Also, how do I correlate the ATA device with actual drives so I know what drive or cable to check?


For now I am going to shut down and remove the parity drive.  I'm leaving town tomorrow for the holidays so I won't have time to fool with it till I get back in a few days.


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Thanks, that seems to have fixed the problem.  The process is now going 80-90 MB/s, and should be done in a day and a half.  5 minutes in and it has already done more than 5 hours yesterday.  I replaced the two cables, and of course gave all the rest a push to make sure they were seated.


Like I said I am still learning.  I'm guessing that ATA# refers to the actual interface, but 3 and 6 didn't correspond to the port numbers those drives were connected to on the motherboard, even if I start counting at 0.  For example, the drives were connected to SATA_1 and SATA_4.  Could you please tell me how you determined which interface was connected to which drive?


Finally, thanks for the tip about the diagnostics tool.  I posted the system log because it was the first thing I found that was full of errors.  I now see that the diagnostics tool includes the log plus other useful info.

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22 minutes ago, jkBuckethead said:

Could you please tell me how you determined which interface was connected to which drive?

It would be easier with the full diags, with just the syslog search for ATA# and press next until you find disk using it, e.g. for ATA3:

Dec 22 21:28:51 Ghost kernel: ata3.00: ATA-10: ST6000NM0024-1HT17Z,             S4D0E03W, SN05, max UDMA/133

Then search for the disk's serial (S4D0E03W) until you find the Unraid assignment list:

Dec 22 21:31:03 Ghost kernel: mdcmd (7): import 6 sdd 64 5860522532 0 ST6000NM0024-1HT17Z_S4D0E03W
Dec 22 21:31:03 Ghost kernel: md: import disk6: (sdd) ST6000NM0024-1HT17Z_S4D0E03W size: 5860522532


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