19 Jan
2007
19 Jan
'07
9:16 p.m.
der Mouse wrote:
I thought it might ;)
Actually,
I've never needed to try this - but is it reasonable to
expect a "modern" system to be able to archive (using dd) a SCSI
drive that's been formatted to something other than a 512 byte block
size?
Depends on the system. :) Last tiem I looked, NetBSD, at least,
couldn't do anything sensible with a SCSI disk with other than 512-byte
blocks. That was quite a while ago, but I haven't heard anything on
the lists to make me think the status has changed.
The thing that got me wondering though - surely in the PC world, SCSI CDROM
drives all use something like 2048-byte blocks? They're still mass storage
devices - albeit removeable ones - and so presumably the low level code *has*
to be capable of working with "odd" block sizes.
I'm sure there's lots of filesystem-level code that's hard-coded to expect 512
byte blocks, but it was the CDROM aspect that got me wondering whether at the
lowl level (dd <==> device) it's most likely to work.
I have a big/small (full-height 5?", but holding
probably no more than
about 1G) drive formatted with 1K sectors, and a SCSI floppy drive that
uses 256-byte sectors, which I keep specifically as examples of
non-512-byte disks. I think the former came from a NeXT, but don't
recall definitely enough to be sure; the latter I forget the source of.
I've got various things that operate at 256 byte block sizes - the problem
being that they're not quite "SCSI enough" to work with modern HBA BIOSes
and
OS low-level SCSI drivers. Until that problem's solved, there's just no way to
archive them using modern equipment, whether the archive step is done using
'dd' or something else. :-(
cheers
Jules