2048kb block size

Kenneth D. Merry ken at freebsd.org
Fri Oct 7 05:05:12 PDT 2005


On Fri, Oct 07, 2005 at 13:08:05 +0300, Danny Braniss wrote:
> hope this doesn't sound too silly, but can the scsi blcksize be set/changed?
> i know that the 'disk' can be formated to any blocksize, the question
> is does the CAM/da know about non 512 block size?

CDROM drives often have jumpers to go between 2048 byte and 512 byte
blocks.

Some hard drives can be formatted for block sizes from 512 to 528 bytes.
Anything larger than 512 in that case is used for per-sector ECC
information and is typically only used by RAID controllers.

The da(4) driver uses read capacity to get the device size and blocksize,
and should be able to handle most any blocksize.  (You might want to stick
with powers of 2, although it would be interesting to see if anything in
the stack breaks with a blocksize that isn't a power of 2.)

Ken
-- 
Kenneth Merry
ken at FreeBSD.ORG


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