Hi,
I find these log messages in my error_log,
[Thu Nov 29 22:59:37.016343 2012] [auth_digest:notice] [pid 9146:tid
139862742857472] AH01757: generating secret for digest authentication
...
[Thu Nov 29 22:59:37.016481 2012] [core:emerg] [pid 9146:tid
139862742857472] (28)No space left on device: AH00023: Couldn't create
the authdigest-client mutex
[Thu Nov 29 22:59:37.016495 2012] [auth_digest:error] [pid 9146:tid
139862742857472] (28)No space left on device: AH01760: failed to
create lock (client_lock) - all nonce-count checking, one-time nonces,
and MD5-sess algorithm disabled
[Thu Nov 29