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From: Rahul on 2 Mar 2010 10:41
I came across this new Western Digital SATA hard drive that has some stuff
going on that I don't completly understand.

They call it "Advanced Format" and has specific jumper settings for various
OS's. But amongst all their special cases Linux didn't figure at all. Now
this could be a good sign: Linux is smart enough to handle this out-of-the-
box without any of the jumpering monkey business. On the other hand it
could also mean that the drive won't play fair with Linux.

http://www.westerndigital.com/en/products/advancedformat/


I'm curious if anyone else is using such drives in Linux. What exactly, is
the "Advanced Format" magic? Western Digital seems to plan on releasing all
new drives with that technology.

The price point was really good on the drive. Specs: 7200RPM SATA; 64 MB
cache. 1.5 Terabytes. ~$150.

Incidently, I bought this drive for a server running a different OS but
ended up putting it in Linux now because of the drive's idiosyncracies.
Linux is usually pretty good at handling diverse HW!


--
Rahul
From: John Reiser on 2 Mar 2010 11:01
> What exactly, is
> the "Advanced Format" magic? Western Digital seems to plan on releasing all
> new drives with that technology.

All drive manufacturers have begun this shift.
The physical sector size now is 4096 bytes, instead of the old 512 bytes.
Firmware in the drive compensates for data transfers that are aligned only to
512-byte boundaries. The compensation takes 3 times as long (read-modify-
write) in contrast to native writes that are aligned to 4096 bytes already.

For best results, use a GPT drive label and align all logical sector counts
(@ 512 bytes/sector) to be a multiple of 8 (16 is even better). For a DOS
drive label, then set the low-level "geometry" so that the product of
(sectors / track) * (tracks / cylinder) is a multiple of 8. For instance,
instead of 63 * 255 use 62 * 252 or even 62 * 248. This is similar to a
flash memory device, where the "erase block" size often is 128KiB, so a
"geometry" of 62 * 128 is preferable to 63 * 255, as long as there is
room for the number of cylinders to be one-bit wider.

--
From: John Hasler on 2 Mar 2010 11:03
The drive manufacturers are switching from 512 byte blocks to 4096 byte
blocks. Windows XP (and, evidently, OSX) can't deal with it so they
have come up with a kludge. They could have said "If you are using
Linux don't worry about it" but, being dorks, they didn't. Note that
even XP will work if the alignment is wrong: you'll just lose
performance.

Here is a link:
<http://storagemojo.com/2009/12/21/why-we-need-4k-drives/>
--
John Hasler
jhasler(a)newsguy.com
Dancing Horse Hill
Elmwood, WI USA
From: Rahul on 2 Mar 2010 11:43
John Hasler <jhasler(a)newsguy.com> wrote in
news:877hpuemne.fsf(a)thumper.dhh.gt.org:

Thanks John!

> The drive manufacturers are switching from 512 byte blocks to 4096 byte
> blocks. Windows XP (and, evidently, OSX) can't deal with it so they
> have come up with a kludge. They could have said "If you are using
> Linux don't worry about it" but, being dorks, they didn't.

Yes, I suspected that. No mention could mean it worked great with Linux or
not at all.

>Note that
> even XP will work if the alignment is wrong: you'll just lose
> performance.

The nameless "other OS" that I bought this drive earlier was WinServer2008-
R2. "Lose performance" is an understatement. :) I had to revert to a
Seagate SAS drive. Hence this project to try and find a home for the
misbehaving-WD "advanced format" drive.



--
Rahul
From: Rahul on 2 Mar 2010 11:44
John Reiser <jreiserfl(a)comcast.net> wrote in
news:MOedndjz0dfrqxDW4p2dnAA(a)giganews.com:

> All drive manufacturers have begun this shift.
> The physical sector size now is 4096 bytes, instead of the old 512 bytes.

Does that have any silver lining or not at all? Or is it just a
manufacturer fad?


--
Rahul
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