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Software RAID5 performance

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a b G Storage
May 19, 2009 3:00:17 AM

I got a Software RAID5 issue (using Windows Server 2003) - i get erratic transfer speeds, then it hangs (from say 104mb/s then a second later to 50, then 90 then it stalls or sits at a few mb/s, then it hangs) - even if i hit cancle and the transfer stops the system still has the HDD led going as if its still going (cached write) - any ideas as to what to change?

Intel E5200
2gb DDR2
Intel Motherboard
3x1tb + 160gb (OS)
Gigabit Lan
Windows Server 2003 R2 SP2

Oh and this is for home use, and i dont trust any single HDD for storage, and i dont really want to spend alot on RAID1 (waste of space etc), and hardware raid cards are expensive.
a c 127 G Storage
May 19, 2009 11:54:21 AM

Many interrupts during the transfer, and your OS does not support polling, or you may be using PCI to communicate with the harddisks. How did you connect your drives, to the chipset controller?

You do know Windows XP/2003 internal software RAID5 does not employ any write-back and it has a misalignment by default, so it will perform very poor when writing sequentially. Should you switch over to something like FreeNAS you would get much better speeds. RAID0, RAID1 and any combination of those should work fine on Windows though.

So, while the read speeds will be quite good, you wouldn't get any good write speeds. You need a Linux/BSD solution for that.
a b G Storage
May 20, 2009 7:59:32 AM

All HDD's connected to the southbridge (ICH10) with AHCI enabled (tried disabled too) - no cards no nothing.

Freenas - already have a 2TB (RAID5 S/W) server using freenas, dont like the lack of some extended features (management, users, NTFS security, SiS function from WSS and VSS etc) and im not impressed by the fussy hardware FreeNAS likes (poor read/writes with most hardware, no dual core support etc) - dont want that for this server and i want more then 47mb/s transfers!.

Looks like ill have to buy a cheap PCIe RAID5 card like the RocketRAID 2300 to get me going unless someone else knows of another decent PCI or PCIe 1x RAID5 card (cant use most PCIx controllers because the motherboard i use has the PCI notches in the wrong spots (PCI 2.3 or 3.0 standard or whatever) to support the cards - Intel DG43NB)

Thanks for the help sub mesa - atleast theres someone who knows what there talking about here on the forums and offers some form of help :) 
!