If a database and log are kept on external storage (NAS in this case), and
if machine A which normally serves the database runs into problems, can we
bring it down, connect machine B and have it take over?

You will want to refer to this tech. note

http://www.ianywhere.com/developer/t..._remotely.html

It discusses both SAN and NAS and specifically addresses the requirements
for
access to any remotely stored database file. For any of this to work 100%
reliably, we require 100% guarantees. Ideally write-order is maintained and
there is no caching of writes.


"Kjetil Valøy" <kjetil.valoy (AT) iticket (DOT) no> wrote

Thanks Nick.. this really helps and leads to a second question:
Assuming the NAS satisfied the conditions in tech note, if the DBMS machine
fails, is there any chance a second DBMS machine could start serving the
database off the NAS (perhaps after running the validity utility to ensure
integrity of data) ?

"Nick Elson" <no_span_nicelson (AT) sybase (DOT) com> wrote

Yes. You should be able to start the database file using an engine on a
different machine provided that the file locations are consistent i.e.,
the path and file name are consistent on both machines.
--

Chris Keating
Sybase Adaptive Server Anywhere Professional Version 8

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Really.. are you effectively saying that the database has path and file
names embedded in it? that seems surprising since I've copied databases with
associated transaction logs from one machine to another and never thought
about being sure the machines had the same directory structure..

"Chris Keating(iAnywhere Solutions)"
<NoSpamPlease_k_e_a_t_i_n_g (AT) i_A_n_y_w_h_e_r_e (DOT) com> wrote

The database embeds log file and dbspace locations in it, but the location
of the database file itself doesn't matter.
The logfile is often specified without a path (which causes the server to
assume it is located in the same directory as the database file), so there
isn't usually a problem in starting the db from another machine.

If the log file is in a different directory than the db file, or you are
using dbspaces, you can fix the locations and get the server up and running.
dblog -t will allow you to change the location of the log file. This will
allow you to start and connect to the database. If you are using dbspaces,
(and they have moved), you can set their location using the ALTER DBSPACE
RENAME statement.

--
Jason Hinsperger
Product Manager
iAnywhere Solutions
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"P Merritt" <pmerritt (AT) transcendonline (DOT) com> wrote