Slow write speed after upgrading from 5.0 RC10 to 5.0.x

[dave_m]

My unraid server is mostly a set it up and then let it run, I don't upgrade it very often.  I used 5.0b12a for quite a while and then went to 5.0RC10 last year, both of which were relatively stable.  I finally upgraded to 5.0.4, and while everything seemed fine initially, the write speed went down quite a bit.

 

On RC10, writing to the cache drive directly reported speeds above 100MB/s, writing to the cache drive through a user share reported speeds of 60MB/s and writing to the 7200RPM parity protected drive reported speeds of 40MB/s.

 

On 5.0.2 & 5.0.4, writing to the cache drive directly reported speeds of just over 30MB/s, writing to the cache drive through a user share reported speeds of 20MB/s and writing to the 7200RPM parity protected drive reported speeds of under 15MB/s.

 

Download speeds from the unraid server were not affected.  Write speeds to the unraid server were tested over SMB and from different Windows 7 and Ubuntu linux machines.  Changing the CPU scaling governor did not make a difference on 5.0.x, and nothing else is running on the server other than unraid.  I disabled unmenu for this testing and was copying various 1GB VOB files for the test. 

 

The motherboard is an ECS A885GM-A2, 4GB of memory, BR10i & M1015 PCIE cards and AMD 250u CPU.  The CPU is low powered, but it's not showing any unusual load in 5.0.x.  The network card is the onboard Realtek 8111DL.

 

EDIT: If I go back to 5.0RC10, the speeds are normal.  The slowdown is only on my main server, my secondary "basic" server is fine on 5.0.4, even though it's using older and slower hardware.

syslog-RC10.zip

syslog-504.zip

[dgaschk]

Try booting with the option that restricts the memory to 4G. It actually restricts the memory to 4095M which changes the way memory is managed.

[dave_m]

I tried 5.0.4 with the mem=4095M option, and no change.  I've also tried swapping out the cache drive for a different one, and switching the controller it was attached to, and no change after either of those.

[dave_m]

And the speed is back to normal in 6.0 beta 1

 

Not sure what to do here.  Assume 5.0.x is just a bad match for my hardware and use 5.0RC10 or 6.0?

syslog-6-beta1.zip

[itimpi]

And the speed is back to normal in 6.0 beta 1

 

Not sure what to do here.  Assume 5.0.x is just a bad match for my hardware and use 5.0RC10 or 6.0?

It might be worth seeing if 5.0.5 works any better if you do not want to run on beta software.

[RobJ]

I've compared the 3 syslogs and see nothing of consequence that is different.  Sorry I couldn't help.

[dave_m]

I'm not sure if anyone else has run into this issue, but I swapped out the motherboard and memory and the 5.0.x series still has slower write speed.  The 6 beta2 and beta5a have normal write speeds.

[garycase]

The slow CPU shouldn't be an issue -- I get consistent 40+ write speeds to the protected array with v5.0.5 on an Intel Atom D525 based system.    Do you have any plugins/add-ons installed that may have compatibility issues with the v5 final release?

 

[dave_m]

Stock unraid, no plugins at all.  New motherboard is Asrock 970 extreme4 with 16GB of memory.  Both use a Realtek onboard NIC, so it could be that driver as well.  I should have a PCI NIC around somewhere, maybe I'll test that out.