Is it possible to setup database mirroring with one primary server and
multiple mirror servers? Thank you for your help.

Best regards,
Rachan Terrell

Currently there is no way of using multiple mirroring databases. I *believe* research is being done
on this feature by the engineering team.

--
Joshua Savill
Sybase Inc. - Product Manager


Rachan Terrell wrote:

Josh,

Thank again for your help regarding to our question on database mirror. Have
a great weekend.

Best regards,
Rachan Terrell

"Josh Savill [Sybase]" <no_spam_jsavill_no_spam (AT) sybase (DOT) com> wrote

Hi Josh,

Thanks for that.

This was something I queried at the last Sybase seminar.

There were a few things that would be great if they were in the product but
I am unsure if they were implemented as the last seminar I went to was SQLA
10.

1) To be able to mirror to 2 mirror servers.
2) To be able to use at least one of the mirror servers for database backup
so that the primary one in production does not suffer a performance hit.
3) To be able to run reports off at least one of the mirror servers. Larger
organisations have end of month intensive querying requiremetns and Crystal
Reporting etc can drain the primary.

Cheers,

Shao


"Josh Savill [Sybase]" <no_spam_jsavill_no_spam (AT) sybase (DOT) com> wrote

Some questions/comments inline below:

Shao Chan wrote:
Are you really wanting two mirrors that can each take the role of primary in
the case that the primary fails? If so why? What is one mirror not good
enough?

I can't remember.... but I think you might be able to backup the mirror in v11.

You can already do this in v11. i.e. you can connect to the v11 mirror and run
queries (e.g. reports).

So to go back to Q1 - are you really wanting to have the ability to fail over
to a mirror server and then fail over to a second mirror server in the case that
the (original) primary and first mirror goes down simultaneously?
If so, can you give us some good examples when this would really happen?
i.e. how likely would it be that primary and mirror both go down at the same
time?
--
Mark Culp
SQLAnywhere Research and Development
Sybase iAnywhere Engineering
-------------------------------------------------------------------------

Hi Mark,

Thanks for the response.

To be fair the second mirror is non-essential provided that the first mirror
allows you to:
1) Run reports off it (you said that its in there now)
2) Allows backing up from.

The only real reason for a secondary mirror is that often the first mirror
is usually very close to the primary mirror, e.g. reporting across a LAN
(although the server would be in another building). However, for business
continuity, the second mirror would be on the other side of the world.
However, this is really a feature that is not really the most important to
have. So long as the above 2 points are covered, that's really the main
concerns and that's pretty much what other database vendors provide.

Cheers,

Shao




"Mark Culp" <reply_to_newsgroups_only_please_nospam_mark.cul p (AT) iAnywhere (DOT) com>
wrote in message news:49CD4CCD.74678661 (AT) iAnywhere (DOT) com...

Marks,



What we try to do is identical to what Shao had said. The first mirror will
act as reporting server (does not need to fail over to) and the second
mirror will be across the country serving as warm stand by (need to be able
to fail over).



Best regards,

Rachan Terrell



"Shao Chan" <NoSpam (AT) NoSpam (DOT) com> wrote

For warm standby, live log backup works well and can be used for
multiple remote locations. I.e., you first run a full online backup
(db and log) to each remote site, and then ON that remote site you
start dbbackup -l (letter el) pointing back at the main site to start
receiving log records. Then, when Bad Things Happen, you apply the
backup log and then the live log file to the remote backup db, and
then start the remote db normally.

If the local secondary becomes the primary, the live log backup is
likely to remain shut off (it gets shut off it loses connection with
the primary), and if you start updating the new primary, the remote db
will become out of date. You could then restart the live log backup to
point at the new primary, and it will start copying log records again.

Caveat: I have NOT used live log backup at the same time as mirroring
is in effect. I am guessing the best bet would be to set the mirror to
synchronous mode.

However, I *have* seen dbbackup -l used simultaneously for multiple
backup databases; e.g., one in the same machine room, one at a
co-location in the same city, and another across the Atlantic. IMO the
"across the Atlantic" was not worth the grief, not on the comm budget
available, but the others worked flawlessly.

Breck




On 2 Apr 2009 12:03:19 -0800, "Rachan Terrell" <web24by7 (AT) hotmail (DOT) com>
wrote:

--
Breck Carter http://sqlanywhere.blogspot.com/

RisingRoad SQL Anywhere and MobiLink Professional Services
breck.carter (AT) risingroad (DOT) com

Scenario
Where 2 or more Mirrors would be helpful / desired.

Primary site

Primary DB and Mirror DB

Primary used for daily activity
Mirror used in Read Only Reporting

COOP site 1 Mirror

Primary site goes down

Coop site is available for daily activity less reporting

COOP site 2 Mirrors
One Primary and one Mirror at Primary site 2 mirrors to COOP site.

Primary site goes down and one of the Mirrors at the secondary site
become primary, the other Mirror at Coop site can be used for
reporting.




On 27 Mar 2009 14:01:50 -0800, Mark Culp
<reply_to_newsgroups_only_please_nospam_mark.cul p (AT) iAnywhere (DOT) com>
wrote: