Re: need for in-place upgrades (was Re: State of

Martin Marques wrote:
> El Dom 14 Sep 2003 12:20, Lincoln Yeoh escribió:
>>>At 07:16 PM 9/13/2003 -0400, Lamar Owen wrote:
>>>'migration' server.  And I really don't want to think about dump/restore
>>>of 100TB (if PostgreSQL actually stores the image files, which it might).
>>Hmm. Just curious, do people generally backup 100TB of data, or once most
>>reach this point they have to hope that it's just hardware failures they'll
>>deal with and not software/other issues?
> Normally you would have a RAID with mirroring and CRC, so that if one of the
> disks in the array of disks falls, the system keeps working. You can even
> have hot-pluggable disks, so you can change the disk that is broken without
> rebooting.

I did mention a SAN running Fibre Channel.  I would have a portion of
the array in one building, and a portion of the array in another
building 1500 feet away.  I have lots of fiber between buildings, a
portion of which I am currently using.  So I can and will be doing RAID
over FC in a SAN, with spatial separation between portions of the array.
  Now whether it is geographically separate _enough_, well that's a
different question.  But I have thought through those issues already.

Using FC as a SAN in this way will complement my HA solution, which may
just be a hot failover server connected to the same SAN.  I am still
investigating the failover mechanism; having two separate database data
stores has its advantages (software errors can render a RAID worse than
useless, since the RAID will distribute file corruption very
effectively).  But I am not sure how it will work at present.

The buildings in question are somewhat unique, being that the portions
of the buildings I would be using were constructed by the US Army Corps
of Engineers.  See www.pari.edu for more information.
--
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute