Someone forwarded your question to me. Here an answer:
Back in 4.0D we started running AdvFS defragment via cron. Many
customers who
did no preventative maintenance on their file systems (ie: no full
backups),
and who had latent file system corruptions (bad disk blocks, metadata
inconsistencies for whatever reason), were suddenly referencing this
old,
untouched data, and the file system was reacting badly to the errors.
As a result from this experience, Compaq began recommending that
customers run
verify prior to running defragment. We realize now that this "big
hammer"
approach was probably too conservative, and downright impractical for
many
customers.
Now, here is a clarification:
If you wish to run defragment, and if you run periodic full backups, or
if you
regularly reference your whole file system, then it is highly likely
that your
file system is "clean", as full backups reference all files and all
metadata,
and running verify becomes optional.
If your filesystem has been untouched for more than a month or two, it
might be
a good idea to run verify during some adminstrative down-time prior to
running
defragment. This will enable you to find and fix any potential problems
during
a controlled downtime rather than when you are running a
business-critical
application.
Hope this is a satisfactory explanation.
- John (AdvFS Engineering Manager)
>>> Paul Thompson <paul.thompson_at_thedacare.org> 01/07/00 03:33PM >>>
One of our sysadmins has just returned from a Digital Unix class and came
back with the information that a advfs verify should be run before defrag is
run. She took this to mean run verify before *every* defrag, I took it to mean
run verify before you turn on defrag for the 1st time or after a system crash.
What is the habit at your site? Has anyone heard recommendations from
DEQ?
I will summarize.
Paul
Received on Mon Jan 10 2000 - 20:18:21 NZDT