Raidz1 write speed/hard drive question

[iScottJS]

Hi all,

First time user of FreeNAS, really liking it but I have a few concerns.

First of all, my set up:
- HP Proliant Microserver N40L
- 4x 2TB WD Caviar Green (3x WD20EARX and 1x WD20EARS)
- 8GB RAM
- FreeNAS 8.0.3 p1 installed to 4GB flash drive

When testing file transfer speeds to/from my Windows 7 machine (using CIFS service), my read speeds are between 80-115mbps which is about the same when transferring from Windows 7 to another Windows 7 machine, so I'm satisfied with that. However the write speed (when transferring a bunch of 200mb files from my Windows7 machine) starts off at about 70-90mbps then drops off suddenly to 35-40mbps and sometimes getting as low as 22mbps. This doesn't happen when transferring from Win7 to Win7. I find that if I transfer one single 200mb file it writes at 100+mbps but if there's a collection it gradually slows down.

I'm trying to work out what could be the cause. After some research I've found that people are saying that the WD20EARS drives incorrectly report sector size at 512 and need to use a jumper to correct it. Is this correct and will this still be affected in FreeNAS even though I select the "force 4k" checkbox when creating the raidz1 partition?

When booting FreeNAS, I see some messages going past reporting that all my drives are 512 but they all should be 4k. Is there a command to find out the reported drive sector size?

Could this be the cause of slow write speeds? Do you think putting jumpers on my drives will improve anything with FreeNAS? What else can I check?

Thanks in advance,
Scott.

 

[William Grzybowski]

I really doubt the 4k sector size your issue:

# zdb|grep ashift
ashift: 12

If you result is the same then you already have a pool configured for 4k.

Not sure what might be causing this though... Did you install eh x64 version?
Some tunning with kmem_size and arc might help, take a look in the forum, plenty of subject about it

 

[lrusak]

usually don't you want to try and set up a raid Z array with the storage disks in a power of 2? (i.e., 2,4,8, etc)

also check this

Code:

dmesg | grep ada

and make sure all the drives are recognized properly. I had to change the drive types in my BIOS from AHCI to IDE to be recognized at the right speed.