I am also interested in this topic.
We were snapshotting our cluster of two nodes every 2 hours (invoked via a
cron job) to an S3 repository (we were running ES 1.2.2 with
cloud-aws-plugin version 2.2.0, then we upgraded to ES 1.4.0 with
cloud-aws-plugin 2.4.0 but are still seeing issues described below).
I've been seeing an increase in the time it takes to complete a snapshot
with each subsequent snapshot.
I see a thread
https://groups.google.com/forum/?fromgroups#!searchin/elasticsearch/snapshot/elasticsearch/bCKenCVFf2o/TFK-Es0wxSwJ where
someone else was seeing the same thing, but that thread seems to have died.
In my case, snapshots have gone from taking ~5 minutes to taking about an
hour, even between snapshots where data does not seem to have changed.
For example, you can see below a list of the snapshots stored in my S3
repo. Each snapshot is named with a timestamp of when my cron job invoked
the snapshot process. The S3 timestamp on the left shows the completion
time of that snapshot, and it's clear that it's steadily increasing:
2014-09-30 10:05 686 s3:///snapshot-2014.09.30-10:00:01
2014-09-30 12:05 686 s3:///snapshot-2014.09.30-12:00:01
2014-09-30 14:05 736 s3:///snapshot-2014.09.30-14:00:01
2014-09-30 16:05 736 s3:///snapshot-2014.09.30-16:00:01
...
2014-11-08 00:52 1488 s3:///snapshot-2014.11.08-00:00:01
2014-11-08 02:54 1488 s3:///snapshot-2014.11.08-02:00:01
...
2014-11-08 14:54 1488 s3:///snapshot-2014.11.08-14:00:01
2014-11-08 16:53 1488 s3:///snapshot-2014.11.08-16:00:01
...
2014-11-11 07:00 1638 s3:///snapshot-2014.11.11-06:00:01
2014-11-11 08:58 1638 s3:///snapshot-2014.11.11-08:00:01
2014-11-11 10:58 1638 s3:///snapshot-2014.11.11-10:00:01
2014-11-11 12:59 1638 s3:///snapshot-2014.11.11-12:00:01
2014-11-11 15:00 1638 s3:///snapshot-2014.11.11-14:00:01
2014-11-11 17:00 1638 s3:///snapshot-2014.11.11-16:00:01
I suspected that this gradual increase was related to the accumulation of
old snapshots after I tested the following:
- I created a brand new cluster with the same hardware specs in the same
datacenter and restored a snapshot of the problematic cluster taken few
days back (i.e. not the latest snapshot).
- I then backed up that restored data to a new empty bucket in the same S3
region, and that was very fast...a minute or less.
- I then restored a later snapshot of the problematic cluster to the test
cluster and tried backing it up again to the new bucket, and that also took
about a minute or less.
However, when I tried deleting the repository full of old snapshots from
the problematic cluster and registering a brand new empty bucket, I found
that my first snapshot to the new repository was also hanging indefinitely.
I finally had to kill my snapshot curl command. There were no errors in the
logs (the snapshot logger is very terse...wondering if anyone knows how to
increase the verbosity for it).
So my theory seems to have been debunked, and I am again at a loss. I am
wondering whether the hanging snapshot is related to the slow snapshots I
was seeing before I deleted that old repository. I have seen several issues
in GitHub regarding hanging snapshots (#5958
https://github.com/elasticsearch/elasticsearch/issues/5958, #7980
https://github.com/elasticsearch/elasticsearch/issues/7980) and have
tried using the elasticsearch-snapshot-cleanup
https://github.com/imotov/elasticsearch-snapshot-cleanup utility on my
cluster both before and after I upgraded from version 1.2.2 to 1.4.0 (I
thought upgrading to 1.4.0 which included snapshot improvements may fix my
issues, but it did not), and the script is not finding any running
snapshots:
[2014-11-13 05:37:45,451][INFO ][org.elasticsearch.node ] [Golden Archer]
started
[2014-11-13 05:37:45,451][INFO
][org.elasticsearch.org.motovs.elasticsearch.snapshots.AbortedSnapshotCleaner]
No snapshots found
[2014-11-13 05:37:45,452][INFO ][org.elasticsearch.node ] [Golden Archer]
stopping ...
Curling to _snapshot/REPO/_status also returns no ongoing snapshots:
curl -XGET
'http://:9200/_snapshot/s3_backup_repo/_status?pretty=true'
{
"snapshots" :
}
I may try bouncing ES on each node to see if that kills whatever process is
causing my requests to the snapshot module to hang (requests to other
modules like _cluster/health returns fine; cluster health is green, and
load is low for both nodes - 0.00, 0.06).
I would really appreciate some help/guidance on how to debug/fix this issue
and general recommendations on how to best achieve periodic snapshots. For
example, cleaning up old snapshots seems rather difficult since we have to
specify the snapshot name, which we would obtain by making a request to the
snapshot module, which seems to hang often.
Thanks,
Sally
On Monday, November 10, 2014 12:27:10 AM UTC-8, Pradeep Reddy wrote:
Hi Vineeth,
Thanks for the reply.
I am aware of how to create and delete snapshots using cloud-aws.
What I wanted to know was how should the work flow of periodic snapshot
be?especially how to deal with old snapshots? having too many old
snapshots- will this impact something?
On Friday, November 7, 2014 8:16:05 PM UTC+5:30, vineeth mohan wrote:
Hi ,
There is a s3 repository plugin -
GitHub - elastic/elasticsearch-cloud-aws: AWS Cloud Plugin for Elasticsearch
Use this.
The snapshots are incremental , so it should fit your purpose perfectly.
Thanks
Vineeth
On Fri, Nov 7, 2014 at 3:22 PM, Pradeep Reddy pradeepreddy...@gmail.com
wrote:
I want to backup the data every 15-30 min. I will be storing the
snapshots in S3.
DELETE old and then PUT new snapshot many not be the best practice as
you may end up with nothing if something goes wrong.
Using timestamp for snapshot names may be one option, but how to delete
old snapshots then?
Does S3 life management cycle help to delete old snapshots?
Looking forward to get some opinions on this.
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