[vox] wd EARS drives in Linux

[Bill Broadley]

On 05/05/2010 06:47 PM, Scott Miller wrote:
> http://www.newegg.com/Product/Product.aspx?Item=N82E16822136514
>
> Anyone know of any pros/cons of the newer Western Digital 'ears' model
> drives in Linux?
> They have 4kB sectors which are larger and different from 512B sectors
> of hard drives in the past.

With 4KB random (unaligned) writes you end up with the ugly case of 4KB 
cross the 4KB boundary so you end up reading 8KB, modify the 4KB you 
need to, and write 4KB.  This is especially painful since once you read 
4KB you have to wait for the disk to rotate again (1/120th of a second 
or so) before you can write.  So the penalty is a factor of 4 in 
bandwidth, and an extra disk rotation (1/120th of a second)..

Not that normal desktop workloads do that particularly much.  It's not 
particularly hard to align a partition table when you create one, but 
you end up with this problem if you accept the defaults.

Here's a decent article on it:
  http://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/

 > i found a few posts like this one saying they are having problems with
 > performance in Ubuntu:
 >
 > 
http://community.wdc.com/t5/Desktop/WD20EARS-in-Ubuntu-has-poor-performance/td-p/16377
 >
 > Eh? Thanks for your advice,