GA-Z68X-UD5-B3 - RAID5 - WD caviar Greens - what write speed should I expect ?

[Daf]

Motherboard : GA-Z68X-UD5-B3
BIOS : F10

OS : Windows 7

HDD Connections :

SATA 0 - Non RAID SATA II HDD - OS boot drive (Win XP 64)
SATA 1 - Non RAID SATA II HDD - HDD
SATA 2 - SATA DVD-ROM
SATA 3 - RAID HDD
SATA 4 - RAID HDD
SATA 5 - RAID HDD

RAID HDD's are all Western Digital Caviar Green - WD15EARS
(2 of one model and 1 of slightly newer)
So SATA II

RAID Array - RAID 5
Seems to work Ok-ISH
Still intialzsing - taking surprisingly long considering I've formatted them (non quick)

Now I wasn't expecting super fast performance as they're "Green's" but currently the write speed is pretty terrible.
Copying several Gigs of Camera Raw files (.Nef files of approx 7Mb each) the speed starts off around 30-40MB/s according to Windows 7. But then fairly shortly it drops to about 2MB/s.
Writing to a memory card over USB2 is about 7MB/s
Writing from one Non-RAID SATA II to another Non-Raid SATA II gives approx 40MB/s

What should in reality expect ?
Is it because Initializing is still going on ?

This RAID Array is going to be primarily for backup - but would prefer it to be quicker.

[Dark Mantis]

Hi,

Your biggest problem is due to you purchasing the wrong type of drives to use in your RAID array. The Western Digital Greens are not at all suitable as they are designed as "Green" power saving devices which means they are always trying to power down. This is no good for a RAID system. Not only that but they don't ramp up fast enough and the RAID controller will probably not pick them up to start with.

You really need something like the WD Blacks for what you are expecting to do. You could try adding a HDD delay in the BIOS to give them the chance to start up in the first place but even then they are not designed for this environment.

[Daf]

Yeah - part knew about the possible issues - but when I had just 2 they were working fine in RAID 1 on my ASUS K8N
Utimately went for economy as they're for backups not quick access.

Would have expected spin-up/down type issues but not V low write speeds when they were working.

Taa for the HDD Delay tip - will give it a go.

Have read stuff about jumper 7+8 about them but seems more for XP.

[Daf]

Hmm - found some posts that raises serious questions on the Intel IRST performance with RAID5:
http://communities.intel.com/thread/18400?tstart=0

Will investigate more - looks like trying different Stripe/Cluster sizes might be worth it + getting a benchmark tool to test inbetween.
Also waiting for Initialisation to end + then turn on caching - but at the current rate that might take a week!

[Dark Mantis]

Nobody said it was a quick job!  Hopefully though you will get there in the end. Some problems seem to be everlasting.