James Bottomley wrote:
On Tue, 2008-07-29 at 12:26 -0600, Matthew Wilcox wrote:
On Tue, Jul 29, 2008 at 01:24:31PM -0400, Ric Wheeler wrote:
Jim pinged me about the use case for having our tool chain (parted
specifically) support devices with non-512 bytes sectors.
Matt Domsch spoke with me about this at OLS. I took that opportunity,
and I'll take this one, to pimp my ata-ram driver which allows you to
alter the sector sizse to whatever you want:
http://git.kernel.org/?p=linux/kernel/git/willy/misc.git;a=shortlog;h=ata-ram
I'll admit to having not tested it with anything other than 512, but it
ought to support 4096 byte sectors just fine. I haven't looked at what
would be required to support 520-byte sectors.
scsi_debug does exactly the same thing, so it reports anything you tell
it (Martin Petersen actually added this so he could test with 4k
sectors).
The problem, which ata_ram also suffers, is that the tools we most need
to test are the ones for manipulating non volatile characteristics (like
partition tables). We'd really like the disk contents to survive reboot
for this ...
SCST (http://scst.sf.net) fully supports non-512 bytes sectors up to
4096. Available target drivers for transports: software iSCSI, FC,
InfiniBand SRP, parallel SCSI, SAS (not much tested, because of lack of
hardware). With VDISK dev handler you can use files as a backstorage.
I personally for a long time have been working with 4K sectors, because
it's better for performance, but so far found the only tool, which
doesn't support them: disktest.
James
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