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Running an Exchange 2016 server currently with CU19.

I have noticed over the years of CU's been applied that the Exchange Server\V15\ClientAccess\OWA folder has grown in size (Currently 9Gb in size, ouch).

On further investigation it would appear that each time a CU is applied it adds its own version (15.1.xxx.x folder) of OWA into the below folders.

  • C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\OWA
  • C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\OWA\Perm

From my searching I understand the Exchange server hangs on to each version so any user can access their mailbox on a different exchange server (not necessarily on the same CU) to match versions for compatibility. ( I could be wrong on this )

However...

I my case this is a single Exchange server in a small business.

So the question is, "Is it safe to delete any of these version'ed OWA folders in either/or/both folders?"

I don't want to just delete old folders if there needed, especially on a production server.

I noticed that there are more OWA version'ed folders (15.1.xxx.x) in the PERM folder than the level up in the OWA folder.

Just wondering if there was some groovy PowerShell tool to check whats needed and tidy up the rest.

Regards.

Ian Chilvers
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  • This seems a bit like tilting at windmills. Why do anything? Is this really a concern? – joeqwerty Mar 09 '21 at 16:17
  • Two reasons. 1) Disk space is a concern on this server and 2) with the recent 0 day exploit on OWA I thought it would be good to clean out anything not actually needed, but which folders is the question? – Ian Chilvers Mar 09 '21 at 18:00

1 Answers1

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Based on my research, you could delete files in C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\OWA\Perm, If you see more than one Exchange build number in it, It means that more than one Exchange version is installed and running in the organization, you can remove old Exchange build numbers from Owa\prem folder and note that don’t remove the build numbers that you see in the Owa folder from the Owa\prem folder.

Before you do that, I suggest you backup this files, We cannot guarantee if deleting these folders will result in any potential problems, and once result in a problem, that would affect the user experience.

For more details: Remove old Exchange OWA files to free up disk space

Joy Zhang
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  • Thank you! This is pretty dissatisfying though (this goes to MS). Manually having to delete files on a production server. Also, I never provisioned the install drive large enough, with the DB and logs being on different drives. – Andreas Reiff Mar 24 '22 at 11:08