[SOLVED] abysmal write speed while reads are okay (network independent)

[SlrG]

I have a big problem regarding my write speeds. Even disk to disk in shell without network usage it is below 2 MB/s.  Read spead over network is 120 MB/s. Read spead without network is around 180 MB/s. Parity check speed is around 160 MB/s. I have attached a zip with info regarding my system, syslog, hdparm info, speed and smart tests. I hope someone with more knowledge has an idea whats wrong.

 

I was on RC11 with a lot of plugins installed, but for the tests I removed the plugins and upgraded to RC12a. It did not help however.

 

SlrG

unraid_hdd_problem.zip

[Joe L.]

I have attached a zip with info regarding my system, syslog, hdparm info, speed and smart tests.

You did not attach anything.

[SlrG]

Have now.

[dgaschk]

The syslog is 83 seconds long. The server runs perfectly for those 83 seconds. The log needs to include a period when the problem occurs. Collect a syslog after writing for 15 or 20 minutes.  Select the 4G RAM option at startup as a test.

[SlrG]

Okay. I'll do both and attach the results. Thank you very much for having a look at my problem.

[SlrG]

With 4G-RAM option the write speeds are way better. 120 MB/s from disk to cache drive and 60 MB/s from cache to parity protected disk. So that solves my speed problem.

 

But I would really like to keep the RAM in the machine and make it work without the 4G-RAM option if possible. I want to run some virtual machines on my unraid and those need the memory. I tried to google around, but I have not yet found further info where the problem is and how it could be resolved.

 

SlrG

[SlrG]

After googling around some more, I found this is a known problem, which will hopefully be resolved later on. I'll make the 4G option permanent for now and mark the thread as solved.