Roch,
true that a fixed-block size filesystems introduces these seek
operations you talked about.
now this has to be counter-balanced with "latencies" introduced in a
log-structures filesystems
(which personally, I am unable to list)
the 10% you talked about is roughly the difference in performance
between QFS and disk-raw speed, in the case of large-sequential-IO
operations...in this particular cornerstone case, no other filesystem
does better (not yet at least)
In orther areas, a log-structure fs (ZFS) will be unbeatable
what we need is to qualify, and to have a global consensus on, where
zfs fits and where it doesn't...I think we are geting there. and I am
pretty sure that will end up saying something like: in "xx% of
workloads, zfs is the N.1 choice" (the "general purpose" paradigm is
reached if xx> 90%)
s.
On 3/30/07, Roch Bourbonnais <[EMAIL PROTECTED]> wrote:
Le 30 mars 07 à 08:36, Anton B. Rang a écrit :
> However, even with sequential writes, a large I/O size makes a huge
> difference in throughput. Ask the QFS folks about data capture
> applications. ;-)
>
I quantified the 'huge' this as such
60MB/s and 5ms per seek means that for a FS that requires a seek per
I/O (QFS ?)
the throughput at infinite I/O size will be at most 10% better than
at 3MB I/O size.
For ZFS the equation does not stand because it does not incur a seek
per I/O.
-r
>
> (This is less true with ATA disks that tend to have less buffering
> and much less sophisticated architectures. I'm not aware of any
> dual-processor ATA drives, for instance.)
>
>
> This message posted from opensolaris.org
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