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<== Date ==> <== Thread ==>

Subject: Re: PV save and restore tool sought
From: Kay-Uwe Kasemir <[email protected]>
To: tech talk <[email protected]>
Date: Tue, 31 Jul 2007 15:23:12 -0400
Hi:

* Is autosave the mainstream tool?
SNS uses it.
It works, but there's something fishy with the errno handling.
Probably more of a vxWorks and network setup error than autosave:
For us, errno is usually set during write runs,
indicating some error, even though all is fine
when looking at the generated files.
The reaction to most errno errors is just a printf anyway,
and we #ifdef'ed those printfs away, since we otherwise
get them all the time,

* What are autosave's and your recommended software's limitations? what
happens in a case of a ioc crash? can backup files be corrupted? Are
backups saved in files or database? Are files the most simple and
reliable architecture? what are the disadvantage/advantages of a
distributed database? central database?
I personally like files because if all else fails,
you can view, edit, compare or create them manually.

* What are the disadvantages/advantages of ioc-based backup utility
versus others designed as ca-client?
I read "The current version of Save/Restore (sr), also known as Bumpless
Reboot, may be interfering with normal IOC operations due to the large
number of file writes." How much of a problem is that, really?
The drawback is that if you have N records configured for autosave,
and only a single one changes, all N need to be written.
Sounds bad, but in practice it seems OK.

* Is there a SIMPLE way to generate a req/request file on the fly for
backup? I have "dynamic" ioc, where the names of records may change
between reboots, or some records may just disappear. Do you have each
time to reconfigure the backup request file? Although I believe this
should be required for a general backup utility, why should it for a
bumpless reboot utility?
Is it possible to generate a req file at ioc startup that save all the
"live" records with name's ending with *O or *AO, etc. ( a dbgrep to a
file can help, but the backup utility needs to reread its config files )
I'm not aware of an existing tool, but you could write your own
tool based on the dbStaticLib: Introspect all records, write whatever
config file you want.

* What happens if the backup utility is looking for a record that
doesn't exist? Is backup still ongoing? Does it significantly increase
the traffic load on the network?
Error message, rest OK.

* What if there are no values previously saved on the particular ioc.
What is the default value? The one in db file?
Yes.

-Kay





Replies:
Re: PV save and restore tool sought Andrew Johnson
References:
PV save and restore tool sought Rock, Judith E.
Re: PV save and restore tool sought Thomas Birke
Re: PV save and restore tool sought Emmanuel Mayssat

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