Exchange Server 2010 on Win 2008 r2

**iRob** · 2012-03-20 08:56

Hi,

I have an interesting question. I have an exchange server that is on windows 2008 r2 and have 5 HD on it. C: windows files, E: that holds one of our Mailbox databases 87.9 GB with 28.8 Free, F: that holds 3 mailbox databases, 147GB with 43.9 Free, G: for Intronis(Thats our offsite data backup), H: Pagefile.

So if go into the E: Drive and add up whats in there and subtract it from the total I get a number that's not the same as whats free. So for this drive I showing that I'm using 52GB. But if I subtract that from the total on the drive I should have 35GB free? What does the drive not reflect this. This also happens on the other drive with the other databases. Also, what is interesting that during the day the size of the drives that show free slowly drop. The somewhat recover the next day but not as much as it went down. Would there be hidden files that I'm not aware of. I already have show hidden files and do not see anything. Does exchange hold onto space somehow? and how do you reclaim it?

Thanks
Rob

***JoeP517*** · 2012-03-20 10:03

Do you show protected operating system files too?

Joe

**iRob** · 2012-03-20 12:24

I did and it does not amount to much that would affect the difference.

**iRob** · 2012-03-20 12:38

I just did a delete from a mailbox of 2,122 messages and the HD space went down from 43.9GB to 42.2GB? I checked all the folders and files on that Drive and nothing has changed anywhere? So the question is why do I lose space when I delete messages? This is very frustrating...

***JoeP517*** · 2012-03-20 15:29

See if Configure Deleted Item Retention and Recoverable Items Quotas helps explain a little. Exchange data storage and data bases is a very complex subject - see Mailbox Server Storage Design for detailed information.

Joe

**iRob** · 2012-03-21 11:13

Thanks for the info Joe. So I checked and my databases are defaulted to 30GB for the recoverable items. Now since the HD space is reduced will I delete the mail does that mean its being moved into this area and that's why the HD is shows the drop? I thought that if your DB on where the mail box was at was at 17GB and you delete something the database size does not grow but puts it on hold for the amount of days before it turns into White Space. I did not think it would affect the HD space immediately?

Thanks
Rob

**Paul T** · 2012-03-21 14:35

Exchange writes log files for every transaction and these are not deleted unless you perform a full backup. It also doesn't recover unused space in the database unless there is lots free - always good to have spare to add all the new mail without having to increase the reserved space.

cheers, Paul

**iRob** · 2012-03-23 08:09

Here is the latest. This drive in question has jumped up to 52.3 GB free and that is where it should be. The last two days I have deleted items that dropped it below46GB and then it brought it up back to over 50GB. So it looks like that drive it working. Now I did not mention this earlier but I have another drive that has a Exchange Database on it and that one is still doing the same thing. Its a 87.9GB drive and now shows 25.4 GB free. I have a database on it that 50GB and if you do the math I should have around 37GB free. I used the windows backup tool on that Drive where that database is kept as well as a full offsite backup and the HD space did not change. In fact today it has gone done a little. Paul what do mean when you said that it does not recover unused space in the database unless there is lots free? Any thoughts now? Now my retention on deleted emails is 8 days. Its been longer than 8 days since I see this drive go up. So here is my next question. About 10 days ago I changed the deleted time from 14 days to 8 days. So by making that change does it reset the counter on mail that was deleted when the retention was at 14? If this theory is correct if I delete a piece of mail in day 1 of the original 14 days and reset the counter to 8 on day 13 it would then take another 8 days past that to clear out?

Thanks
Rob

**Paul T** · 2012-03-25 08:43

All mail lives in the database and when you delete mail Exchange marks the item as deleted, then re-uses the space in the database after the expiry date. It doesn't shrink the database because there are lots of other messages after the one deleted. Exchange needs to defragment the entire database to be able to shrink the database file, not something worth doing regularly because of the performance hit required - Exchange does some defrag as an overnight maintenance job.

Your best option is to make sure the logs are cleared by doing a full backup regularly and having disks big enough to have at least 20% free space, preferably 40% to allow for growth. I recommend you create a space saving file on the disk. Then when the database fills the disk you can delete the space saver and have some breathing space before the system is kaput.
Creating a 10GB space saver: fsutil file createnew spacesaver.dat 10737418240

cheers, Paul

**iRob** · 2012-03-25 11:08

Paul that does not sound good that its going to go Kaput? Here is the thing. I run full backups every night. Even with that my log files are no bigger than 80Meg in those folders where the DB is kept. So I don't see that as the problem. Maybe I'm not explaining this right but no one is answering my question on why my HD disk space is going down? That does not explain why I'm missing at least 10GB worth of HD space? I understand that when you delete mail the DB size does not go down until you defrag it. But that does not answer the question. On that drive there is at lease 26% free.

**Paul T** · 2012-03-27 01:13

You may not be seeing all of the files. Have you changed Explorer to show hidden and system files? An alternative is to run the DOS command "CHKDSK X:" where X: is the drive letter.

My point about the free space is you need to keep some spare in case you manage to fill up the disk - better safe than sorry. The easiest way would be to install another smaller disk and move the log files to the new disk. Then if either the log or DB disk fills up you can clear your space savers and have room to fix the issues without losing data.

cheers, Paul

**iRob** · 2012-03-30 10:32

Thanks Paul. I figured it out. It was the VSS backups that were created and kept the shadow copies on those drives. We stopped that a few months ago and send all those backups to a NAS device now. So I'm good to go. Never thought about that was the issue.

Thanks everyone for your help.

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