[Info-vax] VMS MAIL: PURGE/RECLAIM or COMPRESS?

[Alan Winston - SSRL Central Computing]

In article <0067a4eb$0$30078$c3e8da3 at news.astraweb.com>, JF Mezei <jfmezei.spamnot at vaxination.ca> writes:
>Phillip Helbig---remove CLOTHES to reply wrote:
>> Which is better?  PURGE/RECLAIM locks the mail file for longer.  Do both 
>> have ultimately the same effect?
>> 
>Purge/reclaim is generally much faster. It does an in-file cleanuo of
>mail.mai. It allows a bucket (series of blocks) to be marked as "free"
>again if there are no more active records in it. So if you deleted all
>the records that were stored in a bucked, the bucket is marked as free
>and will be used when you start adding records later on. Otherwise,
>space used by deleted records is not made avaialble for new records.
>
>COMPRESS is essentially a RENAME MAIL.MAIL MAIL.OLD followed by a
>CONVERT/FDL MAIL.OLD MAIL.MAI

Almost.

If it were the order you specify, there'd be a period when mail  delivery was
blocked because MAIL.MAI didn't exist or was locked.

Instead, the convert precedes the rename, and mail that arrives during the
COMPRESS is delivered to the file that at the end is named MAIL.OLD.  Which
means you can't automate  COMPRESS followed by DELETE MAIL.OLD;* (unless you 
can be sure the system was quiescent and mail delivery was shut down) because
you might be throwing away delivered mail without notice.

-- Alan