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How to best set up a 3 disk 4TB Raid 5 in Win7 64bit

Last response: in Storage
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October 6, 2011 7:43:27 PM

Ok firstly here is my situation...

I bought 3 2TB Seagate Barracuda XT and i want to put them in a Raid 5 setup, primarily for the redundancy...

Ive plugged them into my mobo (Asus Sabertooth p67) specifically using 3 SATAII ports since there is only 2 SATAIII ports on that onboard controller... no problems so far...

I set the Sata mode in the bios to raid... Pressed Ctrl-I at startup and configured my raid5 setup with 64kb strip size...
no problems so far...

So i enter Win 7 and goto Computer > Manage > Disk-management and it immediately asks me if i want MBR or GPT partioning... it also says that GPT is recommended for disks larger than 2TB so I choose GPT.
No problems so far...

Now for testing the setup I start by copying a large 1080P bluray image from my WD raptor drive to the Raid-5 setup and at first it seems good. transfer starts at around 140MB/s, but quickly reduces itself all the way down to a crawling 22MB/s.... Which I have a hard time accepting since i expected at least 80+ MB/s for a setup like this...

Now for the sake of trying I delete the drive in Disk-Management and convert it to MBR partioning which only allows for a 2TB drive, but with this setting I at least reach 70MB/s write speed to the drive... Of course this is still unacceptable because I cant utilize the last 2TB of the drive...

What am I doing wrong??? or is this performance on GPT setting to be expected... :pt1cable:  <--- Me going crazy...

What can i do to get this drive up to speed...

Hope u guys can help...

and thx in advance..
a b G Storage
October 6, 2011 7:54:37 PM

Mobo RAID-5 is notoriously slow. RAID-0 or RAID-1 don't have this problem; it's the parity calculation that does it. Are you getting any error messages? The RAID has not degraded?
October 6, 2011 7:58:08 PM

No not degraded, and its only using the GPT setting it crawls down to 22MB/s in the useless MBR mode it sustains 70MB/s
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October 6, 2011 8:19:48 PM

also cpu load and ram usage is only slightly increased while writing to the disk...

Cpu is I5-2500K @3.33Ghz
Ram is 8GB kingston 2000mhz running atm at 1333Mhz
a b G Storage
October 6, 2011 8:27:23 PM

Are there mobo drivers that need to be loaded from CD?
!