cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Nicolas Guyomar <nicolas.guyo...@gmail.com>
Subject STCS leaving sstables behind
Date Mon, 13 Nov 2017 13:04:50 GMT
Hi everyone,

I'm facing quite a strange behavior on STCS on 3.0.13, the strategy seems
to have "forgotten" about old sstables, and started a completely new cycle
from scratch, leaving the old sstables on disk untouched :

Something happened on Nov 10 on every node, which resulted in all those
sstables left behind :

-rw-r--r--.  8 cassandra cassandra   15G Nov  9 22:22 mc-4828-big-Data.db
-rw-r--r--.  8 cassandra cassandra  4.8G Nov 10 01:39 mc-4955-big-Data.db
-rw-r--r--.  8 cassandra cassandra  2.4G Nov 10 01:45 mc-4957-big-Data.db
-rw-r--r--.  8 cassandra cassandra  662M Nov 10 01:47 mc-4959-big-Data.db
-rw-r--r--.  8 cassandra cassandra  2.8G Nov 10 03:46 mc-5099-big-Data.db
-rw-r--r--.  8 cassandra cassandra  4.6G Nov 10 03:58 mc-5121-big-Data.db
-rw-r--r--.  7 cassandra cassandra   53M Nov 10 08:45 mc-5447-big-Data.db
-rw-r--r--.  7 cassandra cassandra  219M Nov 10 08:46 mc-5454-big-Data.db
-rw-r--r--.  7 cassandra cassandra  650M Nov 10 08:46 mc-5452-big-Data.db
-rw-r--r--.  7 cassandra cassandra  1.2G Nov 10 08:48 mc-5458-big-Data.db
-rw-r--r--.  7 cassandra cassandra  1.5G Nov 10 08:50 mc-5465-big-Data.db
-rw-r--r--.  7 cassandra cassandra  504M Nov 10 09:39 mc-5526-big-Data.db
-rw-r--r--.  7 cassandra cassandra   57M Nov 10 09:40 mc-5527-big-Data.db
-rw-r--r--.  7 cassandra cassandra  101M Nov 10 09:41 mc-5532-big-Data.db
-rw-r--r--.  7 cassandra cassandra   86M Nov 10 09:41 mc-5533-big-Data.db
-rw-r--r--.  7 cassandra cassandra  134M Nov 10 09:42 mc-5537-big-Data.db
-rw-r--r--.  7 cassandra cassandra  3.9G Nov 10 09:54 mc-5538-big-Data.db
*-rw-r--r--.  7 cassandra cassandra  1.3G Nov 10 09:57 mc-5548-big-Data.db*
-rw-r--r--.  6 cassandra cassandra   16G Nov 11 01:23 mc-6474-big-Data.db
-rw-r--r--.  4 cassandra cassandra   17G Nov 12 06:44 mc-7898-big-Data.db
-rw-r--r--.  3 cassandra cassandra  8.2G Nov 12 13:45 mc-8226-big-Data.db
-rw-r--r--.  2 cassandra cassandra  6.8G Nov 12 22:38 mc-8581-big-Data.db
-rw-r--r--.  2 cassandra cassandra  6.1G Nov 13 03:10 mc-8937-big-Data.db
-rw-r--r--.  2 cassandra cassandra  3.1G Nov 13 04:12 mc-9019-big-Data.db
-rw-r--r--.  2 cassandra cassandra  3.0G Nov 13 05:56 mc-9112-big-Data.db
-rw-r--r--.  2 cassandra cassandra  1.2G Nov 13 06:14 mc-9138-big-Data.db
-rw-r--r--.  2 cassandra cassandra  1.1G Nov 13 06:27 mc-9159-big-Data.db
-rw-r--r--.  2 cassandra cassandra  1.2G Nov 13 06:46 mc-9182-big-Data.db
-rw-r--r--.  1 cassandra cassandra  1.9G Nov 13 07:18 mc-9202-big-Data.db
-rw-r--r--.  1 cassandra cassandra  353M Nov 13 07:22 mc-9207-big-Data.db
-rw-r--r--.  1 cassandra cassandra  120M Nov 13 07:22 mc-9208-big-Data.db
-rw-r--r--.  1 cassandra cassandra  100M Nov 13 07:23 mc-9209-big-Data.db
-rw-r--r--.  1 cassandra cassandra   67M Nov 13 07:25 mc-9210-big-Data.db
-rw-r--r--.  1 cassandra cassandra   51M Nov 13 07:25 mc-9211-big-Data.db
-rw-r--r--.  1 cassandra cassandra   73M Nov 13 07:27 mc-9212-big-Data.db


TRACE logs for the Compaction Manager shows that sstables before Nov 10 are
grouped in different buckets than the one after Nov 10.

At first I thought off some coldness behavior that would filter those "old"
sstables, but looking at the code
https://github.com/apache/cassandra/blob/cassandra-3.0/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java#L237
I don't see any coldness or time pattern used to create bucket.

I tried restarting the node but the buckets are still grouping in 2
"groups" splitted around Nov 10

I may have missed sthg from the logs, but they are clear from error/warn at
that Nov 10 time

For what it's worth, restarting the node fixed nodetool status from
reporting a wrong Load (nearly 2TB per node instead à 300Gb) => we are
loading some data for a week now, it seems that this can happen sometimes

If anyone ever experienced that kind of behavior I'd be glad to know
whether it is OK or not, I'd like to avoid manually triggering JMX
UserDefinedCompaction ;)

Thank you

Mime
View raw message