I have an Exchange 2013 installation started with SP1 that I have kept updated installing the Cumulative Updates when they were released.

I have observed that after each CU installation the C: free space (Exchange is installed on C:) was less then before. So I searched in the Exchange install directory and I have found a lot of sub-directories named with an Exchange build number, expecially under the ClientAccess install dir and the OWA subdir.

For instance, under C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\Owa I have many folders named "15.0.995.28", "15.0.995.32", "15.0.1044.21", "15.0.1044.27", "15.0.1076.2", "15.0.1076.10".

The C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\Owa\prem directory has the same subfolders and is consuming a lot of disk space.

As I could understand, the CU setup should remove the older files but it seems that it does not and keeps older version in these directories. I have tried installing a fresh Exchange 2013 CU8 on a new server and these directories are not present.

The question is: is that correct?

And: can I safely delete the older versions folders?

Thanks

hmm... weird... I see something similar in one of the environments that I installed recently.  I started with CU6 and went to  CU7 and then finally CU8, but I only have a 15.0.1706.2 in my OWA directories, but I have a 15.0.995.28 and a 15.0.1044.25 and 15.0.1076.9 that are in my ECP directories.

I have more than enough space to hold these directories, but that leads me to wonder why these are here as well.  I guess there are a few things you can do, 

1. Search the ExchangeSetup.log for any directory other than the latest build and see if there was an error deleting those files.
2. If you find an error move the files out to another location, do an IISreset and see if everything still functions. If not, move the folders back, and cycle IIS and everything should be back to normal.
3. If not, you can also try the above.
4. If it is a concern to you contact Microsoft Support and see if they have any further information on what should happen with those folders.

Hi,

Which version are your used now? Please run below command to check: Get-ExchangeServer | fl name,domain,edition,fqdn,serverrole,site,admindisplayversion
More details about Exchange Server 2013 and Cumulative Updates (CUs) Build Numbers (en-US): http://social.technet.microsoft.com/wiki/contents/articles/15776.exchange-server-2013-and-cumulative-updates-cus-build-numbers-en-us.aspx

Besides, ensure everything works fine after upgrade Exchange CU, especial OWA, ECP.
If everything works fine, it cannot be concern.
I also find an similar thread about setup issue where OWA files are not copying correctly in the new version directory, for your reference:
https://social.technet.microsoft.com/Forums/en-US/386ce3aa-dba8-49be-858a-e8e20b70b50b/exchange-2013-cu6-coexistence-with-exchange-2007-ru13-activesync-dont-work-http-error-500?forum=exchangesvrdeploy

Thanks

Thank you Hinte for your answer.

My installation is composed by 4 server. There are 2 Mailbox and 2 Client Access. On the Client Access servers there are less of these "version numbered" directories. One of them has been installed starting with CU8 and it has no directories with version number.

I have searched through the setup log but I could not find any error related to deleting files. But I hev found something that could be interesting.

Last night I installed CU8 and I have searched the ExchangeSetup.log for one of the Mailbox Servers. At the stage "Setup will run the task 'Install-ClientAccessRole'" I have found the following lines:

[06/15/2015 22:35:33.0657] [2] Beginning processing Update-OwaVirtualDirectory
[06/15/2015 22:35:33.0673] [2] Copying the files from directory "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\Current" to target directory "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\15.0.1076.2" on server "localhost".
[06/15/2015 22:35:33.0673] [2] Copying the files from directory "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\Current\ClientBin" to target directory "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\15.0.1076.2\ClientBin" on server "localhost".
[06/15/2015 22:35:33.0673] [2] The file is being copied from "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\Current\ClientBin\OwaSl.xap" to "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\15.0.1076.2\ClientBin\OwaSl.xap" on server "localhost".
[06/15/2015 22:35:33.0673] [2] Copying the files from directory "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\Current\scripts" to target directory "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\15.0.1076.2\scripts" on server "localhost".
[06/15/2015 22:35:33.0673] [2] Copying the files from directory "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\Current\scripts\basic" to target directory "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\15.0.1076.2\scripts\basic" on server "localhost".
[06/15/2015 22:35:33.0673] [2] The file is being copied from "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\Current\scripts\basic\addrbook.js" to "C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\15.0.1076.2\scripts\basic\addrbook.js" on server "localhost".
....

Now I have a "15.0.1076.2" a subdirectory in C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\Owa.

Then I looked in the log files named "UpdateCas.log" and I have found the following entries:

[00:14:21] ***********************************************
[00:14:21] * UpdateCas.ps1: 16/06/2015 00:14:21
[00:14:29] Updating OWA/ECP on server MBX002
[00:14:29] Finding ClientAccess role install path on the filesystem
[00:14:29] FixUnversionedFolderAfterUpgrade: No srcVersions 15.0.1076.*
[00:14:29] Updating OWA to version 15.0.1076.2
[00:14:29] Copying files from 'C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\Current' to 'C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\15.0.1076.2'
[00:14:29] Update OWA done.
[00:14:29] Updating OWA to version 15.0.1076.9
[00:14:29] Copying files from 'C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\Current2\version' to 'C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\prem\15.0.1076.9'
[00:14:45] Update OWA done.
[00:14:45] Updating ECP to version 15.0.1076.9
[00:14:45] Copying files from 'C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\ecp\Current' to 'C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\ecp\15.0.1076.9'
[00:15:04] Update ECP done.

So it seems that the CU setup does not delete older versions of files, at least not Client Access web components files, and it copies them in some - maybe - backup directories.

I have found no documentation about this behaviour, but if this is true it should be safe to remove the older directories, keeping only the more recent one.

Maybe this is done to keep track of some theme's personalization and allow users to recover them after the update... But disk space cannot be infinite, so I think that we should know, for sure, if and when we can delete all those files (the "prem" directory is quite huge on my servers...).

Hi Allen.

Your answer came while I was posting a new message.

As I told, I have no errors, the only concern is about the disk space usage on drive C: (or the Exchange install drive).

Here is the server version and role report you asked:

[PS] C:\Windows\system32>Get-ExchangeServer | fl name,domain,edition,fqdn,serverrole,site,admindisplayversion


Name                : MBX001
Domain              : domain.local
Edition             : Standard
Fqdn                : MBX001.domain.local
ServerRole          : Mailbox
Site                : domain.local/Configuration/Sites/Organization
AdminDisplayVersion : Version 15.0 (Build 1076.9)

Name                : CAS001
Domain              : domain.local
Edition             : Standard
Fqdn                : CAS001.domain.local
ServerRole          : ClientAccess
Site                : domain.local/Configuration/Sites/Organization
AdminDisplayVersion : Version 15.0 (Build 1076.9)

Name                : CAS002
Domain              : domain.local
Edition             : Standard
Fqdn                : CAS002.domain.local
ServerRole          : ClientAccess
Site                : domain.local/Configuration/Sites/Organization
AdminDisplayVersion : Version 15.0 (Build 1076.9)

Name                : MBX002
Domain              : domain.local
Edition             : Standard
Fqdn                : MBX002.domain.local
ServerRole          : Mailbox
Site                : domain.local/Configuration/Sites/Organization
AdminDisplayVersion : Version 15.0 (Build 1076.9)

Now I have understood that the behaviour is correct, or by design, it is not a fault in the setup process. But my last question is still valid: is it safe to delete the backup directories with older version numbers to free disk space?

Thanks