My C drive is almost full and I found a huge Windows.edb file (about 14GB). I also see mailbox .edb files on our old server. What is an EDB file and is it safe to delete?
What is an EDB file and can I delete it?
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Email & Outlook
VL
Victor Lang October 30, 2026
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EDB stands for Exchange Database, but the format (ESE, Extensible Storage Engine) is used by more than Exchange. There are two cases here and they are very different.
1. Windows.edb is the Windows Search index. It lives in C:\ProgramData\Microsoft\Search\Data\Applications\Windows. It is not your data. It is safe to rebuild: Control Panel > Indexing Options > Advanced > Rebuild. A 14GB index usually means too many locations are indexed (for example a big mail archive). Remove those folders from Indexing Options and rebuild.
2. Mailbox .edb files on the server hold the actual Exchange mailboxes. Never delete or move those. Deleting one deletes the mailboxes in it.
Understood. For the server one, can I check whether the database is healthy without mounting it?
Yes, with eseutil /mh "path\Mailbox Database.edb" from the Exchange bin folder. Look at the State line. "Clean Shutdown" means the database is consistent. "Dirty Shutdown" means log files still need replaying, keep the .log files together with the .edb and run soft recovery with eseutil /r first.
Take a copy before you try anything. Avoid eseutil /p (hard repair) unless nothing else works because it throws away pages it can not read.
Rebuilt the search index and freed 12GB. Server database says Clean Shutdown, so nothing to repair. Thanks.