[Postfixbuch-users] Postfix Probleme auf VServer

[Stefan Marx]

..
> 
> Hier ein kurzer Auszug zu den Anforderungen für das Dateisystem der Mailqueue:
> 
> Gory details: the Postfix mail queue requires that (1) the file system can 
> rename a file to a near-by directory without changing the file's inode 
> number, and that (2) mail is safely stored after fsync() (of that file, 
> not its parent directory) returns successfully, even when that file is 
> renamed to a near-by directory at some later point in time. Maildir 
> delivery also requires that (3) a file can be hard linked between 
> different near-by directories. Mailbox delivery introduces no additional 
> requirements beyond what is already needed for Postfix queues.
> 
> 
> Checke das doch mal gegen die Beschreibung von GFS, wie dort fsync und die 
> Zuordnung von File/Inode gehandhabt wird.

Aus dem GFS-Administrators Guide:
...
Ordinarily, GFS writes only metadata to its journal. File contents are
subsequently written to disk by the kernel's periodic sync that flushes
file-system buffers. An fsync() call on a file causes the file's data to
be written to disk immediately. The call returns when the disk reports
that all data is safely written.

Data journaling can result in a reduced fsync() time, especially for
small files, because the file data is written to the journal in addition
to the metadata. An fsync() returns as soon as the data is written to
the journal, which can be substantially faster than the time it
takes to write the file data to the main file system.

Applications that rely on fsync() to sync file data may see improved
performance by using data journaling. Data journaling can be enabled
automatically for any GFS files created in a flagged directory (and all
its subdirectories). Existing files with zero length can also have data
journaling turned on or off.

Using the gfs_tool command, data journaling is enabled on a directory
(and all its subdirectories) or on a zero-length file by setting the
inherit_jdata or jdata attribute flags to the directory or file,
respectively. The directory and file attribute flags can also be
cleared.
...

Vielleicht sollte ich mal nachsehen, ob data journaling auch wirklich
enabled ist. Die Sache mit den Inodes verhält sich meines Wissens nach
genauso wie unter anderen Filesystemen.

Auf dem System selbst wird gar keine Mails abgelegt, es sei denn in der
Queue. Das Fehlverhalten könnte sich mit höherem Mailaufkommen decken,
genau habe ich das noch nicht messen können. Allerdings könnte der Satz
"Applications that rely on fsync() to sync file data may see improved
performance by using data journaling." im Zusammenhang mit den
Fehlermeldungen ala "shared lock active/D/D22C262BC90: Resource
temporarily unavailable" ein Hinweis auf eben dies sein.

Ciao, 

Stefan Marx