SP2 Message Store Size Limit 3

[snootalope]

I have Exchange 2003 SP2 running on Windows 2003 SP2. Works great!

Anyway, I'm trying to understand this "database size limit" that Microsoft refers to:

http://support.microsoft.com/kb/324021

By default, with SP2 installed, the limit is 18GB. But, exactly which files make up the "database" that uses the space?

My setup is pretty simple. One storage group with one mailbox store and one public folder store.

The mailbox store is made up of the priv1.edb and priv1.stm files. Correct? The public folder store is in the pub1.edb and pub1.stm.

So, do all four of those files added together make up the database size?

Or, is the database size determined by just the priv1.edb/priv1.stm files? And if that's the case, that means that by default, the priv1.edb/priv1.stm files can grow up to 18GB without dismounting the store, correct?

Same goes for the public store then, too, right?

So, I could actually consume 36GB by default, 18 for the mailbox store, and 18GB for the public folder store.

Am I understanding this correctly?

 

[ShackDaddy]

Yes, add up .edb and .stm files to get your store size. This goes for both public and private dbs. Each db is considered separately for size, so you could have a 10gb public and 14gb private, for example, and still be under the limit.

But SP2 actually lets you run the size up to 75gb per database...

[link]http://support.microsoft.com/kb/912375[/url]

Dave Shackelford
Shackelford Consulting

 

[snootalope]

Excellent, thanks for confirming that for me.

 

[2624a]

Good question and adequate answer, am a newbie to exchange and i fail an interview question on that. Now I know. Thank you.

 

[mofusjtf]

I believe Exchange 2k3 SP2 actually calculates the logical size of the store not what Windows displays. For example, if you have a lot of white space in your database Windows may show 14 GB (.edb plus .stm file) but actually only have 8 GB of logical size.

Double check this. This may be an Exchange 2k7 feature.

If you set the size in the registry as the exchange kb article says, give yourself a cushion. e.g. set it to 70 GB instead of the full 75 so you can give yourselft some growth room if you do hit your limit.

 

[Zelandakh]

No, it uses the windows file size. So Windows says 75GB and white space / 1221 events say 70GB then you only have 5GB in use but your database is at maximum.
Setting the registry to 75GB for growth room is a waste of time - Exchange grows automatically.

Best to check regularly, ensure you have provision in place and remember that 75GB of Exchange isn't the problem. Disk space is the problem.

 

[snootalope]

Is it possible to see how much white space there is in an Exchange database? Or at least get a more detailed view of the databases?

 

[Zelandakh]

white space is listed in the 1221 event id.

 

[snootalope]

Ok, here's an example of a 1221 i'm getting:

Event Type: Information
Event Source: MSExchangeIS Public Store
Event Category: General
Event ID: 1221
Date: 5/29/2008
Time: 4:15:01 AM
User: N/A
Computer: Mail
Description:
The database "First Storage Group\Public Folder Store (MAIL)" has 38 megabytes of free space after online defragmentation has terminated.

However, if I go to where the pub1.edb and pub1.stm files are kept, those two files combined are only 305 MB. Not even close to the limit. The 1221 message implies that I only have 38 MB of free space. I don't get it!

 

[ShackDaddy]

Your cereal box is consuming a mass of space totalling 305 microliters. After a good shaking, the cereal inside the box is settled in such a way that it is now consuming 268 microliters, which gives you a total of 38 microliters of free space INSIDE THE BOX.

Dave Shackelford
Shackelford Consulting

 

[58sniper]

Now THAT is a good analogy. I think I'll borrow that. An extra star for it.

Pat Richard
Microsoft Exchange MVP
Contributing author Microsoft Exchange Server 2007: The Complete Reference

 

[Zelandakh]

Love it - another star for Dave and a minor theft of analogies heading to the UK too.

 

[snootalope]

Ha, yea that's some good stuff there Shackdaddy.. So, if I understand this correctly, our cereal box is dynamic as well, so if I keep filling it up with cereal, it'll grow as needed to consume both the data and white space (following a defrag) up to 18GB.. right?

 

[ShackDaddy]

Yes, it's an elastic cereal box that expands as needed, but it has no size memory, so you'll have to take it to a vulcanizer (offline defrag) to get it to actually shrink, although you can always free up room inside of it by shaking it on a schedule (online defrag).

It will grow up to whatever the cap is currently set at, which can be up to 75gb with SP2.

When mofusjtf mentioned only setting it to 70gb to give you some expansion room, I actually agreed with him, given that for many admins the "wake up moment" with regard to capacity is often when the store dismounts, and it would be handy to be able to just push the boundary out to 75gb at that point and have a conversation with the CIO in the same hour to discuss either store segmentation or another server.

Dave Shackelford
Shackelford Consulting