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From Flavio Junqueira <fpjunque...@yahoo.com.INVALID>
Subject Re: Transaction logs and snapshots
Date Thu, 16 Apr 2015 09:49:00 GMT
Hi Dejan,
For a typical ZK application, granularity of hours is more than enough, since it is supposed
to be an infrequent background task. In your case, it sounds like durability isn't an important
property because if it is you shouldn't be getting rid of disk data this fast. I'm also wondering
about the amount of data you're generating. What's the size of your snapshots and txn logs?

     On Thursday, April 16, 2015 10:26 AM, Dejan Markic <Dejan.Markic@mobik-ics.com>

 Hello Flavio!

Would that mean, that zkCleanup.sh would not be needed? 
PurgeInterval is minimum 1 hour? Why is it so high?


Kind regards,
Dejan Markic

-----Original Message-----
From: Flavio Junqueira [mailto:fpjunqueira@yahoo.com.INVALID] 
Sent: Thursday, April 16, 2015 11:15 AM
To: user@zookeeper.apache.org
Subject: Re: Transaction logs and snapshots

Hi Dejan,
Check if the autopurge feature solves your problem:

    On Thursday, April 16, 2015 9:17 AM, Dejan Markic <Dejan.Markic@mobik-ics.com>

 Hello all!

We are running 3 ZK servers in ensemble, and ZK is processing a lot of commands per seconds.
There are probably around 300 nodes created/checked/set/get per second.
Since we have only information about live sessions we handle in ZK, we don't need any data
persistency - eg: we can stop all nodes, clean all transaction logs/snapshots, and start them
up again, without any issues.
Since we have a lot of requests/changes, we have moved dataDir onto ramdisk, so we have no
problems with disk IOPS, etc.
Is there a way, to minimze the usage of snapshots/logs so ramdisk would not get filled up?
It happens that transaction logs/snapshots grow so large, that we run out of space on ramdisk.
We issue >/usr/share/zookeeper/bin/zkCleanup.sh -n 3< every 2 minutes, so this should
cleanup the dataDir quite often. Why is >count number of snapshots/logs to keep< limited
to 3 and not below?
I assume, in my setup, I don't even need snapshots/logs to be stored after they are not actively
So my basic questions are:
- can I somehow get rid of snapshot/logs sooner, more often ... ?
- when is snapshot created? Can it be created sooner, so it would be smaller? 
- Is it possible to get rid of snapshot/logs all together?

Thank you for all your inputs and kind regards, Dejan Markic


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