Slow Write Speed

This drive has been in my nas for the last few years

and i noticed write speed was slow around 2 meg a second

so i removed it from the nas (arm9 nas)

and connected it to the pc to my supprise

its still like it on a pc

read speed is just fine

any idea what the problem is

im presuming its hard setting on the drive

Glad to see wd where so quick in providing a solution


Since the problem followed the disk and behaves the same on different OSes, I’d agree there is definitely something going on with the disk.    Given you’ve been doing write tests, I have to assume you’ve already saved whatever data may have been on this drive.  But if not, definitely make a backup.  

You could try doing a SMART extended self-test and see what the values look like after that.  However not all drive problems show up in the SMART data. 

Modern drives must take serious measures to protect the embedded servo data when performing write operations.  If the drive was having some problem with the head assembly or excessive run-out of the spindle (i.e. wobble) the firmware may go into an ultra-careful mode when writing data which could drastically reduce write performance.   However this is pure speculation on my part…

In any case, these forums are only for other end-users to offer assistance.  Given the lack of an obvious cause based on what you’ve posted so far, I would recommend you contact WDC Support who may have additional things to try/check:

I’ve been having the same issue this week, although I’m running slightly faster than your 2MB/s. Tried with different drivers, different power and data cables, different SATA ports, different controller, different machine, with and without NCQ, with and without write caching. I’ve removed all the partitions, overwritten the first and last million sectors with zeroes and reinstalled windows at least 5 times with different service packs and text mode drivers. The problem will not go away in XP or windows 7.

Other drives in my computer are writing fine, including a WD2500JS.

Edit: I also found this guy with the same problem.

Your drives are behaving as if they were reading in DMA mode and writing in PIO mode. But that’s impossible, isn’t it?

Is it possible that Write-Read-Verify mode is enabled on the drives?

You can change this setting with HDAT2:

I can’t do anymore testing as I took the drive back to the shop I got it from.