When you upgrade to Essbase 11.1.2.1 from an earlier release, a backup of the security file for the earlier release is created before the security file is upgraded. The security file backup, Essbase.Bak_preUpgrade, is in ARBORPATH/bin. Unlike essbase_timestamp.bak, which regularly backs up the latest state of Essbase security, this pre-upgrade backup file is kept intact and is not updated by further operations.