IDS Forum

Re: Informix 12.10 snapshot

Posted By: Marcus Haarmann
Date: Thursday, 4 December 2014, at 5:28 p.m.

In Response To: Re: Informix 12.10 snapshot (Madison Pruet)

Hi,

we did something like that for backup purposes (with a LVM2 snapshot, IDS 11.70).
We had the problem that a Level 1 backup of a database with real huge amount of smart blobs
did block the database for more than an hour, because of a known issue.

The only solution from our point of view was to drive a L1 backup from a snapshot,
which is not the same as a level 1 backup from the original device, but does work when the L0 backup is taken from the
original device.
We did it on the same machine, placing links to the chunks in the snapshot in a chroot environment, copy the informix dir,
modify the onconfig then switch to the chroot and startup the database under different name (modified onconfig).
Can be scripted from a good admin as a cron job ...
Of course, doing an external restore can also be a valid solution, but we decided to just copy all the links with a script
and just startup the DB, which could not result in a "forgotten" rename clause.

No external restore because inside the chroot the same device links were active, but pointing to the snapshot devices.
I do not think it depends on the IDS version, 12.10 should have the same possibility.
Just make sure when the snapshot is done the database should be blocked (as you already stated).
We did add a little wait time and checked with onstat if the block was actually done.
Taking the snapshot does not take long, so the blocking of the database was only some seconds, which was
ok for nighttime. (better than a blocking of >1 hour in our case and we could do L1 backups again).

When you do a snapshot either on a lvm level or on a hardware level, keep in mind the device tracks the changes
from each side (active side and snapshot side) to produce the correct block in the snapshot (the original block could have
changed and the snapshot block could have changed, both changes are eating up space). So your snapshots can comsume a lot of
space when you do work on either instance (when you do EMC snapshots, there are different approaches, resulting in different access mechanisms AFAIK).

Marcus Haarmann

----- Ursprüngliche Mail -----

Von: "Madison Pruet" <mpruet@us.ibm.com>
An: ids@iiug.org
Gesendet: Donnerstag, 4. Dezember 2014 23:01:01
Betreff: Re: Informix 12.10 snapshot [34298]

If the instance is really big, then you might want to consider using RS=
S
with a log staging area and setting stop apply at midnight. That way y=
ou
would be able to have a simple cron job that did nothing more than to
update the stop apply every night at midnight.

From: "Art Kagel" <art.kagel@gmail.com>
To: ids@iiug.org
Date: 12/04/2014 11:57 AM
Subject: Re: Informix 12.10 snapshot [34293]
Sent by: ids-bounces@iiug.org

Yes, you can do this. It is easy if the target chunk paths will be the
same on the target machines as on the original. If the paths have to be=

different, I'm not sure you can do it. Read up on "external archive" an=
d
restores in the Backup and Restore Guide or the Informix online
documentation.

Art

Art S. Kagel, President and Principal Consultant
ASK Database Management
www.askdbmgt.com

Blog: http://informix-myview.blogspot.com/

Disclaimer: Please keep in mind that my own opinions are my own opinion=
s
and do not reflect on the IIUG, nor any other organization with which I=
am
associated either explicitly, implicitly, or by inference. Neither do
those opinions reflect those of other individuals affiliated with any
entity with which I am affiliated nor those of the entities themselves.=

On Thu, Dec 4, 2014 at 12:26 PM, GEORGI KOSTOV <gkostov79@gmail.com> wr=
ote:

> Hi all,
> I want to ask is it possible to use SAN snapshot functionality to clo=
ne
my
> Informix 12.10 server?
> I want to make clone of my server every night and to have "fresh" cop=
y of

> the
> instance in the morning on 2 other instances - one on same host and o=
ne
to
> another host for backup and development purposes.
> I do my snapshot with onmode -c block/unblock then storage snapshot -=
my
> question is can I bring other servers with this snapshot.
> Is it posible to have problems with root dbspace?
> PS.my database is too big to make backups and restore with onbar or
ontape.
>
>
>
>
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Messages In This Thread

• Informix 12.10 snapshot
  GEORGI KOSTOV -- Thursday, 4 December 2014, at 12:26 p.m.
  • Re: Informix 12.10 snapshot
    Art Kagel -- Thursday, 4 December 2014, at 12:57 p.m.
    • Re: Informix 12.10 snapshot
      Madison Pruet -- Thursday, 4 December 2014, at 5:01 p.m.
      • Re: Informix 12.10 snapshot
        Marcus Haarmann -- Thursday, 4 December 2014, at 5:28 p.m.
      • Re: Informix 12.10 snapshot
        Fernando Nunes -- Thursday, 4 December 2014, at 5:31 p.m.
        • Re: Informix 12.10 snapshot
          GEORGI KOSTOV -- Thursday, 4 December 2014, at 5:53 p.m.
    • Re: Informix 12.10 snapshot
      NEIL TRUBY -- Tuesday, 9 December 2014, at 2:35 p.m.
  • Re: Informix 12.10 snapshot [34294]
    Luis Panozzo -- Thursday, 4 December 2014, at 2:33 p.m.
  • Re: Informix 12.10 snapshot
    Fernando Nunes -- Thursday, 4 December 2014, at 3:08 p.m.
  • Re: Informix 12.10 snapshot
    Fernando Nunes -- Thursday, 4 December 2014, at 3:12 p.m.
    • Re: Informix 12.10 snapshot
      GEORGI KOSTOV -- Thursday, 4 December 2014, at 5:21 p.m.

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