On Mon, 2003-03-03 at 11:20, Andrew Klaassen wrote:
>
> My half-baked theory at this point is that XFS is less likely to
> respond so slowly to requests under load that Samba/Windows 2000
> give up than ext3 is. I doubt there is any corruption because
> of gaps in the filesystem code itself.
(I'm speaking from my own personal perspective)
Or it just could be the FS itself that makes the difference.
I have my share of experiences with disk-bandwidth-hungry applications
on Linux. I'm doing quite a bit of work with digital video, which is a
very disk-I/O intensive thing.
For example, i'm capturing DV video streams (actually on Digital8
support, not proper DVCAM or DVCPRO or anything) over IEEE1394 (that's
FireWire for you MacOS guys, or i.Link for the Sony gang). I'm using for
that purpose an application that's the bare minimum (dvgrab) so there's
no CPU overhead or anything. The process is entirely disk-I/O bound.
For NTSC 720x480 interlaced 29.9fps 16bit-sound DV stream, the space
requirement is like 16GB per hour.
With XFS, i don't have to worry about anything, i just let it capture
and do other stuff at the same time with that system. I sort of like
that. :-)
With Ext3 it happened, albeit rarely, to get dropped frames if i use the
disks with other applications while capturing, so i have to be careful
with the other stuff i'm doing with the system at the same time.
ReiserFS seems to have the worst performance for this workload (albeit
it's doing great for other things, i won't deny that).
Even when capturing analog video, it's all the same.
Capturing raw YUV is brutal; there's a huge stress on the disk I/O. It's
better to not do anything else at that time, not even touch that whole
spindle, no matter what's the filesystem.
Capturing in lossless compressed formats is slightly better, but at the
cost of some CPU effort.
Capturing in lossy formats such as the MPEG4 family is a lot better from
the disk p.o.v., i could use any FS i want, but then the CPU is used a
lot (only when capturing high-quality material, though), so the system
becomes CPU-bound.
So it's a trade-off, but even then i still see XFS as being the best
choice for the partition where i generate the primary files - it has the
smallest percentage of lost frames in any scenario.
The hardware i'm using are, typically, recent AthlonXP systems, with
large non-RAID IDE drives (yeah, i know), running recent 2.4 Linux
kernels.
--
Florin Andrei
"Do not look into laser with remaining eye." - on a laser pointer
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