Suggestion on either using AOF or Save setting about redis

[GoogleCodeExporter]

Hi, 

Just an added info, I have tried rotating the redis.log of one of our server 
and noticed a few seconds where we had a PING alert for Redis on the server. I 
am not sure if this is a normal scenario or should the logs also cause the 
blockage on Redis when it is Rotated. If rotating the logs will cause this type 
of scenario, please advice on alternative option we can rotate logs and avoid 
it from getting big. 

Thanks,
Jimson

Original comment by [email protected] on 8 Sep 2011 at 1:06

[GoogleCodeExporter]

This is a known issue with Redis AOF log rewriting. You linked issue 602, that 
is the correct one.

Your hang is caused by Linux atomically renaming files and it causing a large 
amount of disk IOs. Using the SAVE configuration option may help some, but 
forking a large process can also hang Redis, it still does an atomic rename 
(though the replaced file is smaller, so this isn't as big a problem as it is 
with AOF), and you only have your data persisted once every X minutes, instead 
of every second.

Original comment by [email protected] on 9 Sep 2011 at 10:42

[GoogleCodeExporter]

Hi Josiah, 

Thank you so much for the information. I had also been doing some reading and 
they are pointing to same problem. We are also additional research for our 
setup to have a work around this issue. 

I would like to check if the log rotation should also have the same affect as 
to renaming a AOF file. I have tried doing a log rotation "redis.log" and I 
have noticed the same problem. Not really sure if this is a know problem since 
I have not encountered a thread having the same information. I am still doing 
additional research on this item. As of now the item I am thinking as a work 
around is to clear the log file after copying it. Some logs will be lost during 
the process but I was thinking this will avoid replacing the current redis.log. 
I would like to get your opinion if this approach is OK. Thank you in advance.

Regards,
Jimson

Original comment by [email protected] on 10 Sep 2011 at 1:07

[GoogleCodeExporter]

Hello Jimson, Log rewriting should not have the same problem AFAIK, but it is 
worth investigating. Are you sure that the delay you are seeing is related to 
log rewriting and not AOF rewriting instead? (or .rdb creation in background?).

Salvatore

Original comment by [email protected] on 12 Sep 2011 at 2:16