Re: Offline defrag

Thank you for feedback, I will be extending the online defrag to last longer
over the weekend.
however I have been going through the event and checking the database size
and I would like your input on the best possible solution forward.

I have 8 mail stores on our exchange enterprise. and I have found some of
the .edb database I have large amount whitespace, causing the file to be
huge,

Here is a little break down of the database size, and space that can be
recovered according to event log entries. the whitespace figures are shown
as they appear in the event log.

Mail Store 1 size 61 gig, whitespace 40914 meg
Mail Store 2 size 211gig, whitespace 158549 meg
Mail Store 3 size 57 gig, whitespace 10740 meg
Mail Store 4 size 64 gig, whitespace 23870 meg
Mail Store 5 size 8 gig, whitespace 303 meg
Mail Store 6 size 37 gig, whitespace 125 meg
Mail Store 7 size 41 gig, whitespace 2437 meg

as you can see some are heavily defragement, could you someone please
advice, I am new to exchange admin. what mail stores should i do offline
defrag on, what should i do before and after offline degraf apart from
taking a back up.




"Kirill Palagin" <kpalagin@xxxxxxxxxxxxxxxxx> wrote in message
news:usAjha71GHA.4752@xxxxxxxxxxxxxxxxxxxxxxx
John Smith wrote:
I have stopped making brick-level backup, and to backup 600gig (cross 8
mail stores) databases took 5 hrs.
this is backing up disk staging system.

So what is different from the time when you were getting 6MB/s?
but I still want to get to bottom of what is causing message level backup
to be soooooooo slow. any ideas on things to investigate to resolve this
issue would be much appreciated.

Take a look at system utilization during BLB, specifically disk IO/ps
my largest mail store database is 210gig with 150 gig whitespace, there
are some mail boxes with corrupt items preventing mailbox move in this
store. what is the best way to reclaim this much space.

If BLB reports corrupt item, it indicates problem with backup software,
not with mailbox.
What happens when you move mailbox?
I have also notices the online defrag always terminated because of back
up interference, so I moved the online defrag back to 2am - 6 am.


Set online defrag to end later, just before you start business day, so
that it has as much time as possible.


"Kirill Palagin" <kpalagin@xxxxxxxxxxxxxxxxx> wrote in message
news:uqPLq$a1GHA.4748@xxxxxxxxxxxxxxxxxxxxxxx

See inline.

John Smith wrote:

it is a company policy that we are able to restore message / folders as
quick as possible, that is why we have invested a lot of money on disk
staging systems. we keep the exchange backup on disk for a week for
the images are expired. I am trying to trace what is causing the
backup performance hit. at the moment we are think it has something to
do with exchange.

"As quickly as possible" is not very specific. Exact time-frame would be
much better. Besides, brick-level backup strategy apparently not
working.


however there is noway to prove this, if there was overall system
performance, a lot of users would have complained. at the moment the
throughput is less then 1 meg for brick level backup and 6meg for IS
backup. backing up 680gig database at the speed will never finish in
time.

Both values seem to be low to me - I expect at least 3 times faster. How
your hardware and all setup looks like? Also, you do not have to backup
680GB all at once - if you split data into, say, 6 databases, you will
be able to backup each in approx 12 hours.


we have imposed storage limits, but people already have huge mailboxes.

how can I do some test to make sure everything in exchange - disk
speed, network link throughput, read/writes of disk system - is working
fine without dismounting the stores.

ExBPA.
http://www.microsoft.com/downloads/details.aspx?familyid=DBAB201F-4BEE-4943-AC22-E2DDBD258DF3&displaylang=en


I didn't quite understand this "(but white space is not backed up
during brick-level backup)." but are they backup during IS backup, I
think they are backup on full IS backup.

Brick-level backup reads each individual item (message, contact,
calendar item etc) in each mailbox and saves this item (which is
slooooow, as it requires many index page reads and sequential reading of
the item parts, like attachments). Since white space in the database
does not belong to any item BLB can not read it.
OTOH, Store-level backup just reads every page in the database
sequentially and saves this stream (which is so much faster). It does
not skip unused pages (white space) of the database.


Online defragmentation is always terminated according to the event log,
this may have something to do with backup schedule times, can I run
online defrag during the day and how much performance hit am I looking
if I was to attempt this.

This could be a problem too - one of InfoStore maintenance (aka online
defrag) tasks is to make freed pages ready for reuse. Not allowing it to
finish will cause white space to grow. You can allow it during business
hours (or just set it for full day).


"Kirill Palagin" <kpalagin@xxxxxxxxxxxxxxxxx> wrote in message
news:%23XpmodZ1GHA.4264@xxxxxxxxxxxxxxxxxxxxxxx

Brick-level backup is infamous for being slow, redundant and
troublesome (but white space is not backed up during brick-level
backup).

Switch to Store backup and you may get 30GB/h and up transfer rates.
After performing successful online backup you can worry about reducing
white space (you can only reduce it, but never eliminate). You can
reduce it either with the help of ESEUTIL or by moving mailboxes to
the other database, whacking .edb+stm, moving mailboxes back. I
strongly recommend ESEUTIL approach.

I also would suggest imposing storage limits.

File-system defrag will not make a difference because database access
is random by nature, not sequential.

John Smith wrote:

we have roughly about 500 users, the last backup took 58hrs to
complete and it didn't backup all the storage groups. we are
performing a brick level backup. To give some idea on how our backup
works, we backup to disk over night, and in the morning this is
staged off to tape. however we have not had a successful backup for
couple days because the throughput is sooo slow. sometimes we see
multiple backup schedule running because the last backup didn't
complete the allocated backup window.

just to make things clear, the total sum of our database are 680gig,
our biggest database 210gig with 150gig whitespace ( Ouch ). the
rest of the database are between 50-100gig and each database has
roughly 12gig of whitespace. Going through the event log and
filtering for event id 1221 and adding up all the whitespaces, we can
roughly save 230gig of space and reduce the databases of 380gig
total.

I can handle the whitespace issue if the backup performance is
quicker, but at the moment backup is slower than snail with
arthritis.

can I also ask if file system defrag would improve anything, if so,
would this require the stores to be dismounted.


"Kirill Palagin" <kpalagin@xxxxxxxxxxxxxxxxx> wrote in message
news:ODv0vFZ1GHA.1288@xxxxxxxxxxxxxxxxxxxxxxx

Having 10GB of whitespace in databases this big should is expected
and should not be cause for offline defrag.
How many users you have and how long backup takes? Hopefully, you
are not doing brick-level backup.


John Smith wrote:

Hi all,

I am new to exchange, we have recently migrated from lotus notes,
where users had unquoted mail files. When we have moved to
exchange 2003, we have decided to introduce quota with the mail
system. so we've created couple mail stores - 8 in total - and
moved users about.

since we've moved users about, out database grew from 370gig to
680gig. I have checked the event log and there is a lot 1221 event
id, it seems that each mail store has approximately 10gig of free
space.

the other thing, our backup has also taking hit, it is extremely
slow, it takes forever to backup. the exchange through put for the
backup has takes a huge performance hit. I think the backup time
interferes with online defrag, I know the obvious thing to do is
run the backup another time, but because of the size of the
databases being backed it is continuously backing 24/7.

I have heard about eseutil, but alot of people are advising against
it, I don't have a recent backup either, I want to fix all this
issues before it becomes a nightmare.

please advice.

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Text from most Windows dialogs can be copied to clipboard with Ctrl-INS.

Free productivity applications suit - www.openoffice.org
Free Internet calling - www.skype.com
Free SQL database Firebird - full support for transaction control,
triggers, stored procedures, partial SQL-99 compliance
http://www.ibphoenix.com/main.nfs?a=ibphoenix&s=1142758270:704186&page=what_is_interbase
Free graphics image manipulation program - www.gimp.org


.

Relevant Pages

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    ... and it has 150 gig of whitespace. ... it turns out that we have over used the first two mail store and now they ... are heavily fragmented and are causing some problems with backup. ... what is the potential that is the will problem with the database size. ...
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  • Re: Offline defrag
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