[comp.sys.hp] Summary: minfree/inodes

paul@eye.com (Paul B. Booth) (02/15/91)

Here's a summary of the responses I got to my posting re. settings for
minfree and inode density in hp-ux kernels.  Many thanks to those who
responded. 

Thoughts on minfree:

The consensus seems to be that 5% minfree could well cause performance problems
in the long run on full disks with a lot of activity.  Most folks counseled
that 10% is more reasonable, but that it might be excessive on larger (>500Mb)
disks.  In any case, it was brought to my attention that minfree can be
adjusted up or down at any time (with tunefs).  

One interesting observation from Hurf Sheldon: 
> All said before is correct except when in a heavily NFS
> dependent environment. It appears that when the NFS server goes
> below 20% free space and there are heirarchical read/writes (someone
> compiling in a server directory on a client) performance drops like a stone. 
> Read only server situations don't exhibit this behavior as 
> badly but a client generated find on a 90% full NFS disk will go much
> slower than on an 80% full disk. (I don't know why - perhaps fragmentation
> causing more disk accesses being queued )

Thoughts on inode density:

People generally felt that the default inode density (1024 bytes/inode) wastes
a lot of space.  Generally, folks recommended 8192 bytes/inode, but counseled
that it might be best to look at a mature filesystem with 'bsd -i' to get
a better feeling for how # of files stacks up against # of free inodes.
Point was also made that different filesystems may have different requirements
depending on their use.

Contributors:

rocky@hpfcmgw.HP.COM (Rocky Craig)
hurf@batcomputer.tn.cornell.edu (Hurf Sheldon)
munir@hpfcmgw.HP.COM (Munir Mallal)
Graham Eddy <graham@hparc0.aus.hp.com>
"Brian Bartholomew" <bb@reef.cis.ufl.edu>
--
Paul B. Booth  (paul@eye.com) (...!hplabs!hpfcla!eye!paul)
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