turning fsync off for WAL - Mailing list pgsql-general

From Ram Ravichandran
Subject turning fsync off for WAL
Date
Msg-id c8cd6fbb0806021712g6659919cjfc84a092ec7e9c3f@mail.gmail.com
Whole thread Raw
Responses Re: turning fsync off for WAL  ("Scott Marlowe" <scott.marlowe@gmail.com>)
Re: turning fsync off for WAL  (Gregory Stark <stark@enterprisedb.com>)
Re: turning fsync off for WAL  (Greg Smith <gsmith@gregsmith.com>)
List pgsql-general
Hey,

I am running a postgresql server on Amazon EC2. My current plan is to mount an Amazon S3 bucket as a drive using PersistentFS which is a POSIX-compliant file system.
I will be using this for write-ahead-logging. The issue with S3 is that though the actual storage is cheap, they charge $1 per 100,000 put requests  - so frequent fsyncs will
cost me a lot.

I've been talking to the makers of persistentFS, and one possible solution is for the file system to disobey fsyncs. I am trying to find out the implications of this method in
case of a crash. Will I only lose information since the last fsync? Or will the earlier data, in general, be corrupted due to some out-of-order writes (I remember seeing this somewhere)?

Thanks,

Ram

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