GBDE performance on ZIP disks
Robert Watson
rwatson at FreeBSD.org
Mon Oct 27 18:27:29 PST 2003
On Mon, 27 Oct 2003, Stefan Walter wrote:
> is there a way to speed up writing to a gbde encrypted ZIP disk?
> Copying 37 MB of data to an encrypted disk (in a SCSI drive) that has
> been initialized with "newfs -O 2 -U /dev/da1a.bde" takes ~180 seconds,
> which is ~200KB/s. Copying the same amount of data to the disk without
> using gbde takes ~50 seconds, which is ~740KB/s.
>
> I guess this problem is similar to the one you have when using msdosfs
> on a SCSI ZIP drive, which is also very slow.
>
> Using a different sector size than the default 512, which is also the
> sector size of the media, doesn't seem to be possible and always results
> in a "gbde: write sector 0: Operation not permitted". Playing around
> with newfs's options didn't help so far, either.
How do things look performance-wise if you do a raw sector read comparison
with dd at various blocksizes? My recollection is that our msdos code
would benefit hugely from the addition of clustering support, but UFS2
with a fragment size matching GBDE's notion shouldn't present the same
problem...
Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org Network Associates Laboratories
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