[ale] Which large capacity drives are you having the best luck with?

Pat Regan thehead at patshead.com
Thu Jan 6 06:23:05 EST 2011


On Wed, 5 Jan 2011 23:31:30 -0500
Greg Freemyer <greg.freemyer at gmail.com> wrote:

> Pat,
> 
> A disk drive physical sector is the equivalent of a network packet.
> 
> It has a header, payload, footer.
> 
> And it has exactly one CRC / ECC value as I understand it.
> 
> The new "Advanced Format" drives from WD have 4KB physical sectors.
> The benefit being less waste to overhead.  ie. Only one header/footer
> per 4KB instead of every 512 bytes.  The ECC is bigger, but not 8x
> bigger.

I would be at least slightly surprised if the firmware performed a
single ECC operation on the entire 512 or 4096 byte sector.

I'd be more likely to expect the ECC to be computed against smaller
pieces of the sector.

I'm not very well versed in ECC algorithms so I could be very wrong and
we don't get good documentation on the data structures that are
actually being stored on a hard drive, though.

> Do you have a rough GB / min rate for the long test?
> 
> With modern drives, I can dd if=/dev/zero of=/dev/sda bs=4k  at about
> 6GB / min.  I can't say I've done a lot of the long tests, but that
> seems about the same performance.
> 
> My 250GB drive says 92 minutes to run the long test.  That's less than
> 3GB/min, so plenty of time to do a full surface scan.
> 

I'm pretty certain that the 1 TB drives I ran a long test on recently
took a similar amount of time to run, about 1.5 hours or less.  I
wouldn't be surprised if the type and quality of the scans vary by
manufacturer and model.

> For files I control, I tend to keep two copies of important files on a
> minimum of 2 media, often 3 or more.  But I've had 2 drives fail
> within hours of each other!  (both young drives during the height of
> Seagate's problems.  Fortunately, replacing the controller card on one
> of the drives brought it back to life.)

I always recommend pairing up drives from different manufacturers.

> I actually like the idea of putting 20 or 30 or more operational hours
> on a drive before putting real data on it.  We write a single pass of
> zeros to new drives before putting them in service, but a couple years
> ago with Seagate, that was not enough of a burn in.  Maybe 3 or 4
> passes would have done it.

I really wish hard drives were more predictable.  I have a large
percentage of drives die in the first few days of service, in the first
few weeks/months of service, and also after a year.  I just have no
trust in any hard drives :).

I was so happy when I switched out my laptop to a proper SSD.  I
figured I wouldn't have to restore from backups as often...  I've RMAed
this drive twice already, probably controller failures each time.

Pat


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