Larger hard drive sectors coming

["Robert G. (Doc) Savage" <dsavage@peaknet.net>]

Slashdot has a post this morning about plans by Western Digital and
other hard drive makers to increase the basic sector size from 512 bytes
to 4096 bytes. This promises to be a very significant change for
hardware and software makers alike.

http://anandtech.com/storage/showdoc.aspx?i=3691

For one thing, it means the hard drives we are using today may not be
usable in future PCs and servers. During the transition period we will
probably see some dual-mode controllers with the ability to use either
native block size. There will also be new hard drives with the ability
to emulate the old 512-byte block size interface. There will be a period
of confusion for both end users and maintainers.

More challenging will be the upgrade of all code that now assumes that
hard drives all have 512-byte sectors. GRUB, LVM, others will have to
evolve to new format standards. Partition tables and Stage 1 boot loader
code have had to co-exist in that first 512 byte sector since 1982 when
the first IBM PC set the standard. That's been terribly confining, but
what choice did we have?

It appears that the first major casualty will be Windows XP. It may live
on as a virtual machine option in Windows 7, but the native version
cannot handle the new hard drives. Vista and Windows 7 are OK. I don't
know for sure, but I'd be surprised if any currently-running versions of
Linux would be affected -- if GRUB is upgraded (and it will be). OS/X
should also be OK.

Why the change?  Larger sector sizes mean larger net capacity for the
user. Today's giant 2TB drives lose a lot of user space to the Error
Checking and Correction (ECC) code used to counter imperfections in the
magnetic surface. By increasing the basic block size from 512 bytes to
4096 bytes, the ECC overhead shrinks substantially. See the Anandtech
article for graphics that illustrate this.

--Doc


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