Den 2013-09-28 16:23 skrev Carlos H. Cantu såhär:

 

It is well known that the writing performance of FB databases on
linux, when you have Forced Writes ON and the filesystem has the
journaling parameter active is horrible and almost unusable if you
have lots of writing (or even worse, massive/batch updates).

Question is:

What would be safer:

Keep FW OFF and Journaling ON
or
Keep FW ON and Journaling OFF
?

I*m going to suggest something unorthodox: if you have performance issues, turn off both journaling and forced writes, and insteasd opt for a tight backup schedule and/or RAID and/or b attery backed-up disk controllers etc.

Also, consider what the risks are re. how likely a computer crash, disk crash, power outtage, etc. are, and compare these risks with the impact of losing everything past your last backup. The backup frequency will be a relevant parameter.

Depending on your case, NBackup might provide a good means of tight backups, e.g. level 0 backup every night, level 1 backup every hour and level 2 backup every five minutes. In that case you would lose max 5 minutes worth of data, assuming the backups are kept in a safe place (i.e. a different disk and perhaps even a different physical location.

For us, we have a dedicated server where they (the service provider) have power backups and we also have the database on a RAID 1 volume. We have forced writes off and do nightly backups to a remote secure backup volume. The likelyhood of a crash is low enough that we can accept to lose on day's worth of updates in the unlikely case it happens. We are considering some NBackup solution with somewhat tighter higher-level backups, but haven't gone through with it yet.

Regards,
Kjell

-- 
--------------------------------------
Kjell Rilbe
DataDIA AB
E-post: kjell@...
Telefon: 08-761 06 55
Mobil: 0733-44 24 64