We will be keeping several copies in service at any given moment, I
hope, so these will be effectively backups that we can go to if needed.
Software upgrades will be pretty rare hopefully and we should not apply
them to all copies at once. I dont'know about the need/urgency of
security patches to the dbms given that the db servers will not (should
not) be directly exposed to the outside world, only through web servers
that connect to them.
It is very rare for a dbms patch to cause data corruption that requires
full recovery from backup, esp. in a read-only db where new data is
appended in a modular way to the db (as we intend to do). We've never
had to do a backup/recovery of the SDSS dbs before/after patches. This
is *much* more likely due to user (operator) error or disk failures,
which we guard against with multiple copies.
A recovery from backup also takes more time and space than just getting
a fresh copy of the db from another server. No matter what, for
performance, fault tolerance, etc., you will need multiple production
copies of the db, either in the same place or at different data centers.
Ani
On Thu, 26 Oct 2006, Becla, Jacek wrote:
> Hi Arun
>
> Yes, that is right, we will archive all previous versions of released
> catalogs. The problem arises if we are forced to make database software
> upgrade in-between data releases. (for example because of security issues, it
> is guaranteed we will not be able to postpone such things 11+ months until
> the next release).
>
> Thanks,
> Jacek
>
>
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED] On Behalf Of Arun Jagatheesan
> > Sent: Thursday, October 26, 2006 2:35 PM
> > To: 'LSST Data Management'
> > Subject: RE: [LSST-data] full db backup before db software upgrade?
> >
> > Hi Jacek,
> > These are problems of technology migration. I thought we
> > discussed this before on this direction without the right "jargon".
> >
> > My understanding is that we will be having a backup of
> > previous versions on the archival system. I don't have the
> > notes to see if we also decided to backup or archive the
> > "un-released" or "the-latest-n-greatest" db also. I think we
> > add this to our archival list, our technology migration
> > strategy should be fine. This might change the numbers (for
> > media and associated
> > cost) by a very little.
> >
> > Another very concerned (paranoid) action item is to also
> > archive the software and configuration files that were used
> > to manage the database.
> >
> >
> > Cheers,
> > Arun
> >
> > ---------
> > PS: This mail was sent (typed offline) during my travel and
> > might not be in sync with any latest developments or replies
> > you might have sent to me or on any related mailing list.
> >
> >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED]
> > > [mailto:[EMAIL PROTECTED] On Behalf Of Jacek Becla
> > > Sent: Monday, October 23, 2006 3:23 PM
> > > To: LSST Data Management
> > > Subject: [LSST-data] full db backup before db software upgrade?
> > >
> > > Keywords: DataAccWG
> > >
> > > Hello,
> > >
> > > I met with CERN Oracle DBAs today. One important point they
> > made was
> > > about making a full backup of database before database software
> > > upgrade. They had a case where (a minor) Oracle upgrade caused data
> > > corruption due to a bug in the Oracle version they upgraded
> > to. They
> > > are planning to keep such backups for a long time, since often this
> > > sort of problems is discovered weeks or even months after
> > the upgrade
> > > (3 months in their case).
> > > Clearly we need to think about a strategy to deal with this sort of
> > > problems.
> > >
> > > Jacek
> > > _______________________________________________
> > > LSST-data mailing list
> > > [email protected]
> > > http://www.lsstmail.org/mailman/listinfo/lsst-data
> > >
> >
> > _______________________________________________
> > LSST-data mailing list
> > [email protected]
> > http://www.lsstmail.org/mailman/listinfo/lsst-data
> >
>
> _______________________________________________
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>
--
Aniruddha R. Thakar, Research Scientist
Center for Astrophysical Sciences, JHU, Bloomberg 375
3701 San Martin Drive, Baltimore MD 21218-2695
410-516-4850, Fax: 410-516-5096
[EMAIL PROTECTED], http://www.sdss.jhu.edu/~thakar
-----------------------------------------------------------------------
Science, like virtue, is its own reward, and its only reward!
[J.L.Wallace]
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