VFS sysctl tuning

[Nikolas Britton]

On 8/12/06, Robert Watson <rwatson at freebsd.org> wrote:
> On Sat, 12 Aug 2006, Nikolas Britton wrote:
>
> > After reading man tuning it said to change vfs.hirunningspace to a larger
> > value. What should I set it to?
> >
> > My RAID controller, an Areca ARC-1220, has a 256MB cache and each disk has
> > 16MB of cache.
> >
> > What other vfs.* sysctls can I change?
>
> The default settings are "reasonable" for many common workloads.  Further
> tuning generally should be done in the context of a specific workload, since
> tuning generally means trading off one type of performance or functionality
> for another.  Only by knowing the workload can we talk about how to trade off
> what you need, and what you don't.
>

Thanks Robert. It's a general purpose server but It's primary duty is
serving files via Samba / NFS over GigE to workstations that are
faster then it. We are typically working with hundreds of (new) ~16MB
files on any given day. It currently has a single dual-core Xeon 5030
and 1GB of system ram. I plan on upgrading it to dual dual-core Xeon
51xx and maxing out the ram if FreeBSD ever gets Xen dom0 support so
we can consolidate server equipment... Anyhow... I decided to script
out the task of finding the right setting for the hirunningspace
sysctl:

#!/bin/csh
sysctl vfs.hirunningspace=1048576
iozone -a -g 1g -b ~/arc1220_18.xls
sysctl vfs.hirunningspace=2097152
iozone -a -g 1g -b ~/arc1220_19.xls
sysctl vfs.hirunningspace=4194304
iozone -a -g 1g -b ~/arc1220_20.xls
sysctl vfs.hirunningspace=8388608
iozone -a -g 1g -b ~/arc1220_21.xls
sysctl vfs.hirunningspace=16777216
iozone -a -g 1g -b ~/arc1220_22.xls
sysctl vfs.hirunningspace=33554432
iozone -a -g 1g -b ~/arc1220_23.xls
sysctl vfs.hirunningspace=67108864
iozone -a -g 1g -b ~/arc1220_24.xls
sysctl vfs.hirunningspace=134217728
iozone -a -g 1g -b ~/arc1220_25.xls
sysctl vfs.hirunningspace=268435456
iozone -a -g 1g -b ~/arc1220_26.xls


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