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EMC's Time Finder for DB backup

P: n/a
Hi all,

anybody out there with experience in using EMC's Time Finder Software
and DB2 UDB EEE on AIX ? Especially in using BCV for Backup ? Any white
papers ?
Nov 12 '05 #1
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4 Replies


P: n/a
Ian
Wanhua Yi wrote:
Hi all,

anybody out there with experience in using EMC's Time Finder Software
and DB2 UDB EEE on AIX ? Especially in using BCV for Backup ? Any white
papers ?


I have worked with EE and EEE/TimeFinder on Solaris platforms. There used
to be a white paper that covered EMC on:

http://www-306.ibm.com/software/data/pubs/papers/

But it seems to be gone. You might try reading the papers that talk about
Hitachi ShadowImage/TrueCopy or IBM ESS FlashCopy -- the overall idea is
the same, just the specific commands used sync/split the BCVs will be
different.
Good luck,


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Nov 12 '05 #2

P: n/a
Not quite. EMC does a disk-by-disk propogation (I'm being a bit sloppy with
the word disk here, I mean the logical "storage volume"), whereas Hitachi
uses a global timestamp over the entire SAN (I'm not sure how IBM's Flash
Copy works). The result is that if data is split over multiple EMC disks,
there is no guarantee of consistency between the two disks, which can
prevent your simply starting your database from the replicated disks an
impossibility (logical inconsistent state).

In any case, any information on Hitach is inapplicable to EMC (except for
that part that explains why EMC's model does not support consistency). BTW,
we replaced EMC with HDS; one of the reasons being the semantic consistency
issue.

As to Time Finder. We have found it useful for failover testing and certain
other "strange" test scenarios where we split entire sets of disks prior to
tests (such as certain hardware changes), but have never used it for normal
database backup actions. DB2's own backup provides much more manageable
point-in.time backup consistency semantics.

Wanhua may wish to talk with his EMC representative.

"Ian" <ia*****@mobileaudio.com> wrote in message
news:40**********@corp.newsgroups.com...
Wanhua Yi wrote:
Hi all,

anybody out there with experience in using EMC's Time Finder Software
and DB2 UDB EEE on AIX ? Especially in using BCV for Backup ? Any white
papers ?


I have worked with EE and EEE/TimeFinder on Solaris platforms. There used
to be a white paper that covered EMC on:

http://www-306.ibm.com/software/data/pubs/papers/

But it seems to be gone. You might try reading the papers that talk about
Hitachi ShadowImage/TrueCopy or IBM ESS FlashCopy -- the overall idea is
the same, just the specific commands used sync/split the BCVs will be
different.
Good luck,


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Nov 12 '05 #3

P: n/a
Thanks, Mark and Ian.
We faced the issue that Mark mentioned in deed. The backup cannot
guarantee the consistency of database because the split on multiply
matchines cannot take at same time. EMC support person cannot resolv
the issue at the moment and they need work with IBM to find result.
What we like to have is to get daily backup on over three Tribytes DB
and we do weekly offline backup. Since it took too long to do online
backup so we hope by using EMC sysmatrix online backup DB from file
system can help.
We would like to take suggestions the try other workaround the issue.
I really appreciate your help.
BTW, is theere any way I can find some related whitepapers? I realy
like do some research on it.
"Mark Yudkin" <my***********************@nospam.org> wrote in message news:<c1**********@ngspool-d02.news.aol.com>...
Not quite. EMC does a disk-by-disk propogation (I'm being a bit sloppy with
the word disk here, I mean the logical "storage volume"), whereas Hitachi
uses a global timestamp over the entire SAN (I'm not sure how IBM's Flash
Copy works). The result is that if data is split over multiple EMC disks,
there is no guarantee of consistency between the two disks, which can
prevent your simply starting your database from the replicated disks an
impossibility (logical inconsistent state).

In any case, any information on Hitach is inapplicable to EMC (except for
that part that explains why EMC's model does not support consistency). BTW,
we replaced EMC with HDS; one of the reasons being the semantic consistency
issue.

As to Time Finder. We have found it useful for failover testing and certain
other "strange" test scenarios where we split entire sets of disks prior to
tests (such as certain hardware changes), but have never used it for normal
database backup actions. DB2's own backup provides much more manageable
point-in.time backup consistency semantics.

Wanhua may wish to talk with his EMC representative.

"Ian" <ia*****@mobileaudio.com> wrote in message
news:40**********@corp.newsgroups.com...
Wanhua Yi wrote:
Hi all,

anybody out there with experience in using EMC's Time Finder Software
and DB2 UDB EEE on AIX ? Especially in using BCV for Backup ? Any white
papers ?


I have worked with EE and EEE/TimeFinder on Solaris platforms. There used
to be a white paper that covered EMC on:

http://www-306.ibm.com/software/data/pubs/papers/

But it seems to be gone. You might try reading the papers that talk about
Hitachi ShadowImage/TrueCopy or IBM ESS FlashCopy -- the overall idea is
the same, just the specific commands used sync/split the BCVs will be
different.
Good luck,


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Nov 12 '05 #4

P: n/a
Ian
Mark Yudkin wrote:
Not quite. EMC does a disk-by-disk propogation (I'm being a bit sloppy with
the word disk here, I mean the logical "storage volume"), whereas Hitachi
uses a global timestamp over the entire SAN (I'm not sure how IBM's Flash
Copy works). The result is that if data is split over multiple EMC disks,
there is no guarantee of consistency between the two disks, which can
prevent your simply starting your database from the replicated disks an
impossibility (logical inconsistent state).


From a DBA perspective, I think the general process is the same:

1) Sync disks (this varies from vendor to vendor)
2) Freeze database
3) Split mirror (varies...)
4) "Unfreeze" database
5) Use mirror(s) on another server.

How the underlying hardware handles the mirrors, and the commands that are
used to manage the mirrors is not really a DBA issue, although that's my
myopic perspective. :-) Maybe it is if you're dealing with a small NAS
device, but with multi-million dollar enterprise storage devices, it's been
my experience that customers typically have someone who knows the device
inside and out.
This issue with Symmetrix is interesting, though. I wasn't aware of this
(and obviously haven't run into it, either). I thought that, once the BCVs
have been synchronized, they remained in sync until they were split from
their primary volumes. The whole point of the 'suspend write' command in
the database is to prevent any I/O (and the applies across all partitions)
while the mirrors are split. Once the split has completed, then I/O may
be resumed ('resume write').

I agree that it would not make any sense to try and split mirrors while
the database is still actively performing I/O.

Do you know of any white papers that explain this issue in depth?

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Nov 12 '05 #5

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