Hi,

Investigating high availability and warm standby solutions.
Yes, I know they are different, but bear with me.


1) High Availability

On the link below,

http://sybooks.sybase.com/onlinebook...1250e/ha_avail

... why are there 2 sections for Sun:

"Configuring Adaptive Server for FailOver on Sun"
"Configuring Adaptive Server for FailOver on Sun Cluster 3.0"

.... but both sections actually require Sun Cluster ?


Also, it mentions that one of the requirements is that devices must be accessible to both nodes.
So I presume that this is actually a shared-disk subsystem ?
e.g. I have an A1000 disk array, connected to 2 hosts ?



We are also looking into warm standby solutions.

2) Standby A


One idea we have in mind is just like the above, a shared disk subsystem,
where an A1000 is attached to 2 hosts, using disk sets on Solstice DiskSuite so that only one
ever has ownership of the array ( and thus only one host and write to the array at any point in time ).
However, was told that for this to work properly, we actually needed Sun Cluster for this to be supported.
So given that we need Sun Cluster to do this, we were still wondering if we need Sybase HighAvailability for a warm
standby solution. I was assuming not.

Thus, if one host fails, we simply startup ASE on the other host and let it have ownership of the diskset in the array,
and we are up again. Of course, we have to point all database connections from the previous host to the new one.
Any comments / ideas / warnings ?

Is this supported by Sybase ?


3) Standby B

Use Replication Server. This would mean we can have different hosts using totally different disk devices.



Which among the above are:

*) The easiest to implement and maintain, taking into account applying patches to ASE,
upgrading from one version to another, making backups and restores, etc. ?

*) Cheapest to implement ? It may seem that Replication Server actually requires more disks,
but removes the single point of failure ( shared disk subsystem ), but that can be taken care of
using 2 disk arrays, mirrored between each other.


Regards,

John

On Tue, 27 Apr 2004 07:06:52 +0000, noone wrote:


I haven't worked with HA, but implementing and maintaining Warm Standby
systems with Rep Server is pretty straightforward, and it makes applying
patches/upgrading/etc. fairly easy as you can suspend replication and
upgrade the standby side, and then switch over to perform maintenance on
the (ex) primary.

As for costs - I think that you may need a little more hardware for a warm
standby (complete duplicate environments/machines) though you could
probably use network attached storage or a SAN that is partitioned and
shared by both systems if you wanted to.

You also need to figure in the licensing costs for Sybase, rep server, etc.

Michael
--
Michael Peppler Data Migrations, Inc.
mpeppler (AT) peppler (DOT) org http://www.peppler.org/
Sybase T-SQL/OpenClient/OpenServer/C/Perl developer available for short or
long term contract positions - http://www.peppler.org/resume.html

Michael Peppler wrote:

My problem currently on warm standby with Sybase Replication Server is that manual seems to focus more / goes onto great length
on replicating objects within a database ( replicating tables, stored proces, etc ... )
when what I need is replicating the database ....

Do I have to replicate the master , sybsystemprocs database here ?

After performing an upgrade on the stanby site, and shutdown the primary to perform an upgrade on the primary site,
does it automatically "switch" back the to the primary site when the upgraded primary site is up ?

OK, I have no experience on Replication Server.

On Wed, 28 Apr 2004 05:58:19 +0000, noone wrote:

No - but you probably need to sync master..syslogins and
master..sysloginroles between the two servers.

No - switching is always a manual operation, and there is nothing inherent
in the WS setup to prevent a client to connect to the standby instead of
the primary... so you need to have a set of guidelines and/or procedures
to make sure that all clients connect to the primary (unless they are
read-only clients)

Michael
--
Michael Peppler Data Migrations, Inc.
mpeppler (AT) peppler (DOT) org http://www.peppler.org/
Sybase T-SQL/OpenClient/OpenServer/C/Perl developer available for short or
long term contract positions - http://www.peppler.org/resume.html