Oliver Fromme wrote:
Guy Helmer wrote:
> I think we've finally found the cause of the problem - it wasn't just
> occurring after heavy use, but was visible right after filesystem
> creation! We regularly built new filesystems with "newfs -U -O 1 -b
> 65536 -f 8192"
Why are you using those blocksize and fragsize settings?
(If you store large files, then you should at least also
decrease the inode density, using the -i option.)
These settings were chosen to optimize I/O throughput for Postgresql on
the theory that a 64KB block size would maximize disk throughput in the
general case (especially for a RAID 10 system) and an 8K frag size would
match Postgresql's page size.
I wasn't aware of any known regressions in 6.x regarding large
filesystem block sizes...
Some time ago, Joe Greco wrote:
> > the one unusual thing about the configuration is that the filesystem
> > we are attempting to build on is a 136GB ccd across 4 scsi disks with
> > the fsize=8192 and the bsize=65536 (it is mainly to be used for large
> > data log files):
>
> FreeBSD doesn't support fsize/bsize so large. There are ongoing issues
> within the filesystem code and VM code that will cause such filesystems
> to break under heavy load. Matt Dillon also talked about this being less-
> than-optimal for the VM system from some technical points of view.
It has been a while, and I'm not sure if there are still
problems with those non-standard fsize/bsize settings, but
I would definitely try to avoid them for production use.
Best regards
Oliver
Thanks,
Guy
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