October 3, 201510 yr This is my first parity sync since upgrading to version 6, and for the most part it was running at 35.5 MB/sec. Once down to the last two 3TB drives the speed bumped up to 61 MB/sec. On the unRAID 5.x the parity sync and checks were in the 90's for the most part. Nothing really has changed since 5.x other than one of my drives being taken out of the array. Any idea what could have caused this slowdown? Thanks, Lev tower-diagnostics-20151003-1859.zip
October 3, 201510 yr Community Expert Known issue with a single core celeron, if you can upgrade to any dual core cpu and you'll have speeds close to what they were with v5.
October 3, 201510 yr Author Known issue with a single core celeron, if you can upgrade to any dual core cpu and you'll have speeds close to v5 Really? 6 is that much more taxing? I guess I can drop in an 8400 or q6600. It never even occurred to me that I may need more power!
October 3, 201510 yr Community Expert V6 needs more horsepower, your cpu is probably pegged @ 100% during a parity check, any dual core will do but you might as well get the best one you can.
October 3, 201510 yr Author V6 needs more horsepower, your cpu is probably pegged @ 100% during a parity check, any dual core will do but you might as well get the best one you can. Right now, running at around 69 MB/sec CPU utilization is around 85%. So, would you go with a fast 2 core or a quad? Is V6 optimized for 4 cores?
October 3, 201510 yr Community Expert It's only at 100% when it's reading all disks, when the speed was 35MB/s
October 4, 201510 yr Author It's only at 100% when it's reading all disks, when the speed was 35MB/s I'll run a parity check after the sync, and then change for a different cpu and rerun parity check to see the difference.
October 15, 201510 yr Author Well, after some back and forth, I've upgraded to an E8400 dual core. Currently running parity check and am rather disappointed with the present speed. It's 33.8 MB/sec. CPU utilization does not go above 45%, so why is the parity check still so slow?
October 15, 201510 yr Community Expert That’s to slow for an e8400, if you didn’t change anything else in your config something else is going on. I see your "md_sync_window" is set to 60, this is way too low, well below the default 384, wich is already low for some systems, try with the default value.
October 15, 201510 yr Author That’s to slow for an e8400, if you didn’t change anything else in your config something else is going on. I see your "md_sync_window" is set to 60, this is way too low, well below the default 384, wich is already low for some systems, try with the default value. Sorry for the noob question, but what is that setting and where do I find it? What should it be optimally?
October 15, 201510 yr Community Expert Settings / Disk settings Start with the default, if it improves then you can run tunables tester to find the optimal setting.
October 15, 201510 yr Author Settings / Disk settings Start with the default, if it improves then you can run tunables tester to find the optimal setting. Thanks. I'll give it a go once the current parity check completes.
October 16, 201510 yr Author I changed the md_sync_window value to default (Not even sure how it was changed to 60. I never adjusted those values), and moved my parity drive off of the controller card and placed it on the native sata port. Now, after about 15 minutes of re-running the parity check the speed is up to the 80's. Pretty much where it was with v5.x Thank you for the advice, Lev
October 16, 201510 yr Community Expert Good to know that it’s back to normal. Try to keep your disks evenly distributed on both SASLPs as they are a somewhat bandwidth challenged, the bottom SASLP shares the DMI link with the on-board ports so for best results and in case you get more disks avoid more than 5 or 6 array drives on the top SASLP and more than 8 total on the bottom one + on-board ports.
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