Write Performance of UNRAID

[msobon]

I recently dove into unraid as the technology seems promising for the poormans storage and here come the questions!

 

To give a little of a backround of the setup I'm using:

 

SUPERMICRO 3U RACK MOUNT SERVER CASE CSE-933T  (Yields 15 SATA hotswap bays)

SUPERMICRO X7SLA-H Atom Boardhttp://www.supermicro.com/products/motherboard/ATOM/945/X7SLA.cfm?typ=H

1 Gig or Ram

3x 2TB Seagate

 

So the system is quite recent and it's basically going to replace my current 9TB Raid 6 array which resides on my Promise Supertrack EX8350.

The initial tests I have are that unraid seem to have the following results on my system:

 

Write: 30 MB/s~

 

Read: 50 MB/s~

 

Burst Read: 80 MB/s~

 

 

The question I have is why the super slow write speeds? I understand the drive needs to write parity and that does takke some out of the system performance but with the drives being capable of close to 100MB/s sequncial why such a big perfomance cut?

S

Is there some system perfomance tunign that can be done to improove this?

 

to answer tthe networking question, it all resides on a Full Duplex 1Gigabit network that has been tested and I hae toggled Jumbo frames on and off but to discover and re-confirm the network is not the bottleneck.

[dgaschk]

The parity drive must be read and the update parity written back. Your performance is reasonable. Use a cache drive to speed up overall performance.

[Joe L.]

The parity drive must be read and the update parity written back. Your performance is reasonable. Use a cache drive to speed up overall performance.

BOTH the parity disk AND the disk being written must FIRST be read and THEN written back.  The disk platter on BOTH disks must rotate to get back to the sectors just read to perform the writes.  The SLOWEST ROTATING DISK involved sets the overall speed of writes to the array.

 

Joe L.