Slow write speed to disk.

[vik2or]

Hi
I have to start with the fact that I am new to freenas and linux. I wanted to make a small ftp transfer server, (and maybe use it for backup too). I had an poweredge 1950 web server that I didn't use anymore so I put freenas on a 8gb thumb drive added 2 1tb WD green (I know is not the best solution, but I read that they are ok if you disable the sleep function - WDIDLE)

The disks are in a mirror zfs volume

Now, here's the problem. When i try to copy something in LAN on it it starts in gigabit speed then after a few seconds it drops to 100mbps.

Because it starts at gigabit speeds I excluded the network as a problem. I had 4gb of ram initially but after reading trough the forum I ended up buying another 4, but nothing changed. I tried to mess with the tunable, using different values form different posts that had a similar problem, but it didn't help.

After a few reinstalls, I started looking at the drives, and there found something weird (at least form my noobish point of view)

zpool iostat write bandwidth seems capped at 10MB. and I can't figure why,

I disabled the hardware raid because I read that zfs doesn't get along with it..

Does anyone know what could cause that bottleneck and can help me with this? Please say if you need me to give more info.

Thank you,
Victor

 

[cyberjock]

Please post all the hardware in your server...

 

[vik2or]

Dell PowerEdge 1950 1U

CPU: Intel(R) Xeon(R) CPU X5355 Quad-Core @ 2.66GHz
RAM: 4 x 2Gb DDR2 667Mhz Fully Buffered
Integrated SAS 5/i Contorler
I don't remember exactly if it has an optional PERC 5 or a PERC 4 Raid Controler
Dual embedded Broadcom NetXtreme II 5708 Gigabit Ethernet (not connected in LAG)
2x 1Tb WesternDigital Green HDD (with WDIDLE disabled)

And the 8Gb USB thumb drive from Kingstone

 

[cyberjock]

So when you setup the SAS 5i controller for these disks did you have to set the disks up as RAID0 single disks?

Can I get a debug file from your system? System -> Advanced -> Save Debug.

Thanks.

 

[vik2or]

In the SAS admin screen I left the drives as independent drives, didn't add them in any raid format

Here is the debug info

 

[vik2or]

I still have this problem. I removed all autotune tunables and tried without autotune, nothing changed (btw, should i keep autotune active? does it help or not overall).

Is there a way i could narrow down on the problem? Can i test the write to disk speed somehow, without going trough cache/ram, so i would know if is a software problem or a hardware problem (controler, drives)?

dd gives random values

dd if=/dev/zero of=dumpfile bs=8192k count=100
100+0 records in
100+0 records out
838860800 bytes transferred in 58.553844 secs (14326315 bytes/sec)

dd if=/dev/zero of=dumpfile bs=8192k count=100
100+0 records in
100+0 records out
838860800 bytes transferred in 3.420999 secs (245209305 bytes/sec)

dd if=/dev/zero of=dumpfile bs=8192k count=100
100+0 records in
100+0 records out
838860800 bytes transferred in 95.393220 secs (8793715 bytes/sec)

 

[hugovsky]

You can try reading this thread. You have good examples there.

 

[hugovsky]

Also your hardware is not very good because of FSB.