Ying-Hung Chen wrote:
pre-allocation before writing would still be your best bet. If you
pre-allocate on a fresh fs before writing, you should get very large
extents.
does this mean, if I create a 2GB file via dd (not sparse file), when i
'overwrite' to the same file, it will stay there? (same physical place)
Other things you could try; if you put each file in its own dir, it will
tend to go into its own allocation group.
You could make the filesystem with allocation groups sized at 2GB
I just thought of wild idea... since i am creating 90 files, what if i
just create 90 allocation group via -d agcount=90, does this make sense
or it won't work at all?
Thanks,
-Ying
From reading your emails, I don't think that it is the problem of the
fragmentation.
I understand that we don't need to defragment the filesystem while we
are working
on the unix/linux. I don't need to deframentation a raid drive, which
the size
is 2TB, with XFS filesystem.
I guess while you played your video file, which was 2GB. Your video
images were not smoothly
shown on the player. It gave you an impression that there was a problem
on the filesystem.
I don't know whether your 200GB drive is an ATA, SATA or SCSI drive.
A fast SCSI drive is the best drive for the video stream. If you can
stipe several SCSI drives
into a volume, and the performance will be improved.
I hope that I can help you to solve your problem.
Andrew
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