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Immediate Purge of Deleted Files

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Posted: 24 Jan 2003
 

Novell Technical Support: TID10078808

The NetMail (and NIMS) documentation highly encourages the "Immediate Purge" option and talks about the need to purge the volume frequently if immediate purge is not enabled, but it fails to emphasize just how many temporary files NetMail creates. A busy NetMail server can fill a volume with deleted files in a matter of hours.

NetWare, by default, saves deleted files so they can later be salvaged. That is a great idea for directories used for a file server, but is unnecessary and inefficient for directories in which an application (such as NetMail) creates lots of temporary files. The NetWare developers created the "Immediate Purge of Deleted Files" on a system and directory level to accommodate such uses of the file system.

NetMail commits everything to disk to make sure that data does not get lost while being processed. NetMail, consequently, creates an enormous number of temporary files. When "Immediate Purge of Deleted Files" is not set for a directory used by NetMail, the volume quickly becomes full of deleted files. When more than 80% of the "free" directory entries get full of deleted files, all file system calls become slow. Every time NetMail deletes a file, NetWare has to go through an extensive process to decide which file it needs to purge to make space for the newly deleted file. In the time it take to find and remove the oldest deleted file, NetMail is waiting to delete dozens more. This results in very sluggish NetMail performance and high utilization.

If RAM is not abundant, this can also result in memory allocation problems. The slower the file system becomes, the longer it takes a NetMail thread to do its assigned task. The longer the thread stays around, the total number of running threads on the system increases. The more running threads on the system, the less available RAM there is. It does not take long for this to spiral out of control.

Many temporary files get created in the NetMail MAIL_STORE directories. Every time a message is purged from a mailbox, the following process happens:

  • All the remaining messages are written to a new file and the file is written to disk
  • The original mailbox is deleted
  • The new file is renamed to become the new box file.

In addition to the temporary files created in the message store directories, up to a dozen temporary files get created in the SPOOL directory every time a message goes through. Every time a message is composed in Modweb, several temporary files get created in the WORK directory. Additional files are also created here while ModWeb processes various forms.

Only temporary files are created in the NetMail WORK and SPOOL directories. There is never a need to salvage a file from these directories. NetMail will not delete a message here unless the message has been successfully delivered or bounced.

Enable "Immediate Purge of Deleted Files" on the NetMail WORK and SPOOL directories

To automate the process of purging NetMail's temporary files, you enable the Immediate Purge of Deleted Files option in Monitor so NetMail will immediately purge deleted files.

Related Links:

For more NetMail tips visit: NetMail Tips for Administrators


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