Does this disk/filesystem layout look sane to you?

[Chuck Swiger]

Hi--

On Jun 16, 2009, at 5:53 PM, Andrew Reilly wrote:
> I bought a pair of identical WD 750G SATA drives the other day
> and was surprised to discover that they were different sizes:
>
> ad4: 715403MB <WDC WD7500AACS-00D6B1 01.01A01> at ata2-master SATA150
> ad6: 715404MB <WDC WD7500AACS-00D6B1 01.01A01> at ata3-master SATA150
>
> Luckily for me I built the file systems on ad4, and added ad6 to
> the gmirror configuration.  I suspect that it would have been
> unhappy if I'd done it the other way around.

Agreed.  However, you might want to look carefully at the first drive  
via smartctl or even WDC's own utilities.

It's not unusual for a drive to have some small area(s) of the disk  
surface which cannot record data reliably and hence are marked as bad  
sectors in the initial factory-provided P-LIST, and to keep some  
reserves as spare sectors for bad sectors which happen during normal  
operation (the 'grown' list aka G-LIST).  If that is the reason (and  
there could be others-- you might even want to ping WDC's tech support  
about this), it's surprising that the amount of sectors marked bad is  
enough to change the reported size in megabytes.  You might also want  
to double-check the actual physical label on the drive and watch out  
for an "RM" or "remanufactured"/"recertified" indicator.

Regards,
-- 
-Chuck