WD20EARS in Ubuntu has poor performance

I am preparing a couple of disks for use in an Unraid storage server. Unraid uses a Slackware distribution and seem to prefer ReiserFS on the storage disks. I am planning to copy data from my other disks to my new WD20EARS on an Ubuntu10.4 system, and then install the disks in the Unraid server. The other hardware is the onboard SATA of an HP Pavillion 4660 (AMD board).The WD20EARS is connected to the first SATA hosta adapter. From specs it says chipset is NVIDIA GeForce 6150 LE Southbridge: nForce 430 (also called MCP51)

My problem is unexpectedly poor performance when copying data from a 1000 GB drive on the second SATA host adapter. A file copy starts off at 30MB/s and is rapidly decelerating to 20 MB/s, when I cancel after a minute or so. I was expecting far better performance on disk to disk copy. Using the Ubuntu disk utility to measure performance, I get a very (inverse)spiky performance graph. See the linked pic. Performance graph

On the Unraid forums some people suggest the performance will increase (by 10-20%)  if the Advanced Format jumper is set. I try to set a jumper on the pair closest to the SATA connector (7-8 by info on support site), then Ububtu does not see the drive after booting. This operation is made with no partition on the drive. It doesn’t even show up in the disk utility.

SHould the disk to disk performance be this low? Is there a reason for the performance graph to look like this? My other disks show a more level curve, like I would expect. And is there a reason why Ubuntu will not acknowledge this disk with the Advanced format jumper set. I am sort of disappointed and consider returning this disk to store…

Happy for any advice,

Lars Olof

as far as I know the jumper has to be set before ever creating a partition
and that it’s supposed to be specific to windows XP (though 2k is also affected)
if there’s already a partition on the disk, adding the jumper most likely causes the disk’s controller to be confused
which might be why the system can’t see the disk,

have you attempted to realign the partition with the WDAlign boot CD?
or manually aligning the partition to proper 4K sector boundaries?

that downward spiking is most likely because the drive is having to write accross the sector 4KB boundaries
and because of that it has to wait another revolution before it can see the first sector again
in artificial / simulated 512byte sectors there are 16 sectors simulated on 2 4KB sectors,
the drive reports 512byte sectors at the interface but handles the data on disk as 4KB sectors

this was supposed to be only an XP / 2K etc. problem as those OS demand 512byte sectored HDD’s

but it would seem that it’s a problem to LInux also and I wouldn’t be surprised if Unix & Mac’s suffer the same grief

I have 2 of the EARS 1TB HDDs installed in my XP-32 system and after the WDALign tool was used
I get better performance though I still get the initial lag of the translation on first accesses of files / folders
but once the file read or write has started the performance is comparable to any other 512byte sectored HDD
but I wouldn’t say that the performance is any better