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Slow Write Speed


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Can't seem to find an answer to my question in previous posts.

 

Currently I have unRAID setup over 100mb lan. The router does not have a live connection, just a link to //tower and a link to the management console. I'm using 4 1TB Seagate drives and no parity drive. I've clocked my write speed at about 8-9MB/sec. Is that normal? Is it simply due to the 100mb limitation?

 

Thanks.

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Just a quick look, no obvious errors, but hdc is an identical drive to the other SATA drives, yet appears to be installed on an IDE connector?!?  Perhaps you are using a SATA-to-IDE adapter?  That could be slowing things down.  You have 4 Seagate ST31000340NS drives, sdb, sdc, hdc, sde.

 

Otherwise, you are very close to the limits of 100mbps Ethernet, practical limit is around 10 to 11mbps, theoretical limit around 12.5mbps.

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Check your BIOS settings, make sure the SATA ports are not in an IDE or Emulation mode.  They should be in AHCI if available, or a native SATA mode, or else an Enhanced mode.  And 15 seconds sounds about right for an average to slow flash drive.

 

Also, I don't know what your motherboard is, but it looks like it supports gigabit.  If you were to purchase an inexpensive gigabit switch ($50), you should see a significant improvement in read speeds, and a very small improvement in write speeds, to parity protected drives.

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Check your BIOS settings, make sure the SATA ports are not in an IDE or Emulation mode.  They should be in AHCI if available, or a native SATA mode, or else an Enhanced mode.  And 15 seconds sounds about right for an average to slow flash drive.

 

Also, I don't know what your motherboard is, but it looks like it supports gigabit.  If you were to purchase an inexpensive gigabit switch ($50), you should see a significant improvement in read speeds, and a very small improvement in write speeds, to parity protected drives.

 

Can you define significant improvement? I have a gigabit router at home, but not here in my test environment. It will go home once testing is complete.

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So just a little update these are my current speeds over gigabit lan:

 

Read - ~62MB/Sec

 

Write - ~42MB/Sec

 

(Both sustained)

 

I'll post speeds with cache drive installed later. Here's my hardware setup for reference:

 

Lian-Li A17B

GIGABYTE GA-MA74GM-S2 AM2+/AM2 AMD 740G Micro ATX AMD Motherboard

ICY DOCK MB455SPF-B Multi-Bay Backplane Module x 2

CORSAIR CMPSU-650TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Power Supply

G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL5D-4GBPQ

4 x Seagate 1TB ES.2

2 x Seagate 1.5TB (not live yet, one will be used as cache)

 

 

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You can't be getting 42MB sustaining writes with parity.  Well, put another way, if you are then the rest of us want to know how.

 

How specifically are you testing?  A good test is to write an entire DVD (4+GB).

 

 

Cheers,

Bill

 

UPDATE: Ah, I see that you have no parity.  That should be the same performance as with a cache drive, btw.  All the cache capability gives you is a drive outside of parity with a cron'd copy function.

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Check your BIOS settings, make sure the SATA ports are not in an IDE or Emulation mode.  They should be in AHCI if available, or a native SATA mode, or else an Enhanced mode.  And 15 seconds sounds about right for an average to slow flash drive.

 

Also, I don't know what your motherboard is, but it looks like it supports gigabit.  If you were to purchase an inexpensive gigabit switch ($50), you should see a significant improvement in read speeds, and a very small improvement in write speeds, to parity protected drives.

 

I have recently begun using AHCI on some of my other machines. Switching this after an OS is setup has caused me issues in the past! Can anyone confirm that unRAId doesn't have kittens when you switch from some other mode to AHCI?

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