Our department is finally getting a dedicated server to handle NFS,
and system daemons. It will be a headless 4/166 with about 9G of
local disk space spread across 5 disks. The local filesystems will
all be AdvFS.
My question lies with tuning the beast under Digital Unix 3.2A. I've
previously configured alphas to be compute servers or workstations;
this will be the first time I've tried to configure a machine to
optimize file-serving performance. It'll have 48M of memory to start
with, and will run no user procs other than things like sendmail, DNS,
NIS, license managers, etc. I'd like most of the memory to be used by
the kernel for buffering AdvFS and NFS.
I assume that bumping up ubc-minpercent and ubc-borrowpercent will
allocate more memory to io subsystem. Does anybody have any
real-world numbers? I was thinking something like ubc-minpercent=20,
and ubc-borrowpercent=35. might be good starting point for a dedicated
server.
Also, all local filesystems will be AdvFS, not UFS. How do you
compile UFS out of the kernel, or at least not waste much memory on
buffers you won't use?
According to the docs (section 3.5.1.3 of the dxbook 'Tuning
Subsystems and Applications') the bufcache parameters (bufcache,
buffer-hash-size, name-cache-size, name-cache-hash-size, etc) are
specific to UFS. However, sysconfig shows them as part of the vfs
subsystem.. and setting them to 0 causes a machine to panic on
booting, so I assume one can't set them all to 0.
Looking at the bio_stats struct via kdbx -k on a running kernel (3.2A)
w/only AdvFS disks shows all items 0, except for:
getblk_misses = 1
getnewbuf_calls = 3
This confuses me...
And how does one allocate extra memory to the AdvFS equivalents of
these buffers? The Tuning guide is rather skimpy on AdvFS tuning
hints, other than 'balance and defrag often.'
Are there any other general words of wisdom from people who have set
up Alphas as NFS servers using AdvFS as the local filesystem?
Thanks in advance. In addition to your replies, I'll summerize my
real-world experiences (if the darned box ever shows up! ;-)
Drew
##############################################################################
# Andrew Gallatin, Computer Project Manager #
# Institute of Statistics and Decision Sciences #
# Box 90251, Duke University, Durham, NC 27708-0251 #
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Received on Tue Sep 05 1995 - 19:51:29 NZST