[Orca-users] VXFS fragmentation

[Lightfoot.Michael]

This reply is largely off topic...

> -----Original Message-----
> From: Liston Bias [mailto:bias at pobox.com] 
> Sent: Friday, 24 January 2003 9:46 AM
> To: orca-users at orcaware.com
> Subject: [Orca-users] VXFS fragmentation
> 
> 
> We have identified a bug in VXFS 3.4 that is not allowing us 
> to reaname a file if it happens to exist in directory with 
> fragmented directory inode. We are working that issue with 
> Veritas... but it got us thinking.
> 
I'd like to read up on this, where is it docuemnted on the Sun or
Veritas sites?  We haven't upgraded to 3.4 (it was planned but pushed
into the background when other projects of a more urgent nature arose.)

> We don't ever run vxfs fsadm on our systems unless problem identified.
> 
> In reasearching docs, there is recommendations ranging from 
> daily to monthly cron of this function on systems.  I know it 
> is I/O intensive to run these functions, so am looking to 
> "display" the fragmentation that actually exist to justify runs.
> 
> Has anyone taking a shot at graphing fragmentation with orca?
> 
It's probably a pointless exercise unless fragmentation changes rapidly.
I run a frag report on our two systems with VxFS every Sunday morning at
about 3am.  I have run a defrag once in 12 months and only because I
wanted to check that the defrag script worked (so I could complete the
documentation for the systems.)

One of the advantages of VxFS is that it doesn't fragment very quickly,
even on busy systems, unlike UFS which can go bad very quickly.  I have
two squid proxy caches which are currently on UFS and they are already
(after less than 3 months) getting significantly fragmented (I don't
graph this with Orca either - just run a daily emailed frag report using
fsck -n.)

At another site I workjed at nearly two years ago I convinced management
to fork out the dosh to put all my top tier squid proxy caches on VxFS.
As far as I know they only need to defrag these every six months or so
(they all have 8GB cache directories, some with two and some with four)
unlike the previous UFS ones that caused problems (one actually ran out
of free blocks) after less than 4 months.





Michael Lightfoot
Unix Consultant
ISG Host Systems
Comcare
+61 2 62750680
Apologies for the rubbish that follows...
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