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Exchange white space - 28.Jul.2008 10:43:01 AM

jammer8

Posts: 6
Joined: 10.Jul.2008
Status: offline

Hi

We have several mail stores; our largest (both .edb and .stm) is 170Gb and 90Gb free space on the drive. We have 68Gb whitespace which grows by about 1Gb a month according to 1221. Am i right in saying that its only worth moving mailboxes to a clean store when the white space gets to <30% of the store size? We have split our stores into surnames A-C, D-F, etc. and A-C is the huge one above. By the nature of most surnames being A-C i wanted to move all users to another drive; trash the old stores and re-create a A-B for example and move them back. When should i look at starting this process or is there a better way?

thanks in advance
James

< Message edited by jammer8 -- 28.Jul.2008 10:45:45 AM >

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RE: Exchange white space - 29.Jul.2008 12:58:04 PM

ratishnair

Posts: 21
Joined: 29.Jul.2008
Status: offline

Event ID 1221 and Database Free Space

Event Type: Information
Event Source: MSExchangeIS Mailbox Store
Event Category: General
Event ID: 1221
Date: 01/01/2005
Time: 00:04:16
User: N/A
Computer: SERVER
Description: The database "First Storage Group\Mailbox Store (SERVER)" has
3.4 megabytes of free space after online defragmentation has terminated.
They then post a message about their Exchange server running out of space, and how to increase it.

There are a number of issues here, which will be dealt with separately.
What does this message mean?

What it means is that Exchange has carried out some routine maintenance on the Exchange database. Any old data that is past the delete thresholds has been deleted from the database.

The space it has left behind has then been consolidated, in to "white space". The size of the database hasn't changed - there is just some space within the database.
This "white space" will be used by Exchange first, before expanding the database any larger.

What happens if the size is very large?

It depends what you mean by large, and how large your Exchange database is.
For example, if your Exchange database is 200gb and the message says that you have 50mb free, then that isn't a massive amount of that space.
However if your Exchange database is only 10gb and the message says that you have 500mb free, then it is taking a larger proportional amount of the database.

Can I reclaim that space?

Exchange will use that space, so if your Exchange server is used heavily, then that space could be used up very quickly.
If your server is lightly used however, then you might consider an offline defrag. This uses a tool called eseutil.exe which you can find in the \exchsrvr\bin directory on your Exchange server.
The decision to do an offline defrag should be weighed up carefully.
It will cause downtime of Exchange as Exchange needs to be stopped while it is running. It isn't the fastest of tools, but your downtime will depend on the size of the database.
You need approximately 2.5 times the size of the files in free space - so if your database is 10gb you will need 25gb of free space.
Running eseutil.exe on the database should NOT be considered routine, or part of the maintenance of the server. Exchange looks after itself, and eseutil should only be used on those rare occasions where a large amount of data has been deleted and the space needs to be reclaimed.
Does the message have anything to do with the size of the database?
No, it doesn't.
However you do need to monitor the size of the database if you are using Exchange standard edition, or are on a Small Business Server. These versions only allow a database of 16gb. If you exceed that, Exchange shuts down.
At that point you can use event ID 1221 to verify if there is lots of white space, so that you can do an offline defrag to get Exchange running again.

Why does it cause confusion?
This event log ID should have been worded slightly differently - changing the word "free" to "white". This would have given a clearer indication of what has happened. The message would then read like this:
"The database "First Storage Group\Mailbox Store (SERVER)" has 1 megabytes of white space after online defragmentation has terminated. "

More Information
There is more information on the way that Exchange uses the database and the true size of the database in this Microsoft article: http://www.microsoft.com/technet/prodtechnol/exchange/2003/insider/trueamountofspace.mspx

(in reply to jammer8)

Post #: 2

RE: Exchange white space - 29.Jul.2008 1:53:19 PM

consultOz

Posts: 901
Joined: 11.Mar.2005
From: Virginia, USA
Status: offline

You are on the right track; do not waste your time with performing offline defragmentation.
The best way is to move users into new mail stores. The design of the databases up to you and I would recommend keeping smaller databases instead of one big mail database. The rule is simple smaller the Database the happier the exchange will be (easy to deal with small DB versus big one)
You should keep empty mail store in the future do perform same process to for eliminating white space.
Schedule the mailbox move in the night this should be transparent to your users. Just be carefull with the log drive space issue, possible going out of disk space during the move process. Circular login is there an option if you run into this problem, but remember Circular login is not a permanent configuration and is not recommended by MS to use as normal configuration. Also make sure you will have a good backup of your mail data if you happen to enable circular login

--oz

< Message edited by consultOz -- 29.Jul.2008 1:54:45 PM >

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(in reply to jammer8)

Post #: 3

RE: Exchange white space - 31.Jul.2008 10:10:49 AM

jammer8

Posts: 6
Joined: 10.Jul.2008
Status: offline

Hi

Thnaks for the response. That is interesting what you said about logging - during the move mailbox process the log files increase dramatically on the source server, is that what you are implying? If this is the case is there a rule of thumb - i.e. a percentage of the amount of data you are moving, so to make sure there is enough free space on the trans.log drive?

thanks
James

(in reply to consultOz)

Post #: 4

RE: Exchange white space - 31.Jul.2008 7:26:35 PM

bigdaddychi

Posts: 1
Joined: 31.Jul.2008
Status: offline

Just remember that when you move the mailboxes you will lose SIS, so even though mailbox moving is a faster way to deal with white space you will lose SIS which can be a bad thing as well.

(in reply to jammer8)

Post #: 5