In case you ever wonder what these messages in system.log mean:

Apr 2 13:12:34 mac com.apple.backupd[20052]: Warning: Destination /Volumes/Machine does not support Server Reply Cache

Apr 2 13:12:34 mac com.apple.backupd[20052]: Warning: Destination /Volumes/Machine does not support TM Lock Stealing

The OS X client correctly reports here that the Netatalk AFP server is missing two AFP features:

  1. Server Reply Cache”
    This is a new AFP 3.3 feature advertised to enhance reliability of AFP connections in case of intermittent connection drops. Netatalk has not yet implemented this feature and it’s not part of the current development roadmap.

    Summary: don’t disrupt your network connection while backing up with TM!

  2. TM Lock Stealing
    Another AFP 3.3 feature important in dealing with connection drops. This one though is less important for Netatalk then it is for AppleFileServer, because Netatalk uses a process per AFP connection, while AppleFileServer uses a threaing model. In case the server Netatalk afpd process of a specific connection crashes, it’s locks are gone anyway.

    Anyway, since Netatalk 2.0.5 there’s the option options:tm which you can specify in AppleVolumes.default which will make Netatalk tell the client it supports lock stealing, which in fact it does as described.

Update (Feb-17-2011):
Netatalk 2.2 (to be released soon) will support the AFP “Server Reply Cache”. How nice!
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