May 28, 201610 yr Been doing some testing on network transfers, My WD Red drives are able to get 110MB/s over the network. My old Samsung drives jump all over the place 40 to 90MB/s (avg 55MB/s), they are old drives been running non-stop for the last 5 years on my last server. When copying from the Samsung drives the CPU usage spike to 90% during the transfer. Anyways, wondering why the Samsung drives push the CPU but the not the WD drives. All drives running from the MB controller. All drives pass SMART tests. I have Cache Directories plugin installed. Not sure if that is doing anything?
May 29, 201610 yr Community Expert There's an issue with unRAID v6 and these disks that when used in a AHCI controller it considerably slows down parity checks/syncs and disk rebuilds, I never noticed the high CPU usage, but it could be related, if you have a non-AHCI addon controller try it, if nothing else it should considerably speed up your parity check.
May 29, 201610 yr Author Thanks for that. I might end up moving these drives along and get more WD Reds instead.
May 29, 201610 yr Author A new controller like this is cheaper then new drives and lets me expand later. Would this be a good choice? I understand this card is good to go out of the packet? (LSI Internal SAS SATA 9211-8i) Samsung drives should work with it? http://www.ebay.com.au/itm/New-LSI-Internal-SAS-SATA-9211-8i-6Gbps-8-Ports-HBA-PCI-E-RAID-Controller-Card-/281409936840?hash=item418556ddc8:g:wJcAAOSwQ15XOYDL
May 29, 201610 yr Community Expert That controller will solve the slow parity issue, it should also solve the high CPU usage if it's related.
June 1, 201610 yr Author I ended up replacing the 4 x 2TB Samsung drives with 2 x 4TD WD REDS (Parity took half the time @ 111 MB/sec) I tested some file transfers, and some files slow down to 80ish MB/sec and CPU usage spikes. Not all files cause it. (Testing on MKV files) I can replicate it on certain files. Could be the makeup of an MKV file? Anyways still getting the CPU 90%+ on some transfers. Other MKV files transfer with very little CPU usage. Attached diags if anyone can have a look. server-diagnostics-20160601-1836.zip
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