The original intent of sync, to guarantee a successful commit to hard
disk for every write, is generally lost in modern environments.
Virtualization, and the use of object storage, obfuscate the physical
constructs beneath such that the application and/or server can no longer
make hardware guarantees. For this reason attempting sync in that kind
of environment might make you feel good, but it isn't doing exactly what
that old school guarantee implies.
In the case of a physical server with a local disk sync can still
provide the guarantee, but it is expensive from a resource standpoint to
do so. Advances in controller and disk technology have come a very long
way since the functionality of sync was introduced, and to this old
admins view most of the reasons for using it are in the process of
disappearing into history.
It probably explains why the "-" is now meaningless in the config files,
why not doing it is the default, and why you must explicitly enable the
behavior yourself assuming the responsibility for any performance
degradation.
Regards,
On 9/11/19 12:57 PM, David Lang via rsyslog wrote:
by default, rsyslog always buffers logs and doesn't sync after each
message, so the - is ignored.
David Lang
On Wed, 11 Sep 2019, Brian Candler via rsyslog wrote:
Date: Wed, 11 Sep 2019 14:55:55 +0100
From: Brian Candler via rsyslog <[email protected]>
To: Brian Candler via rsyslog <[email protected]>
Cc: Brian Candler <[email protected]>
Subject: [rsyslog] omfile flushing behaviour
Another minor question.
In legacy format, you may prefix each entry with the minus "-" sign
to omit syncing the file after every logging.
What's the equivalent when directly using omfile? Is it
flushOnTXEnd="off", or sync="off"? (the latter is default anyway)
Thanks,
Brian.
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