"I don't what hardware information may help"

A low memory server will produce an intensive use of CPU and disk IO. It will write a lot of small SSTables which will need to be compacted very often. That was one of my thought when I asked.

Alain

2012/10/15 Manu Zhang <owenzhang1990@gmail.com>
I use default option for compaction:
   in_memory_compaction_limit_in_mb: 64
   multithreaded_compaction: false
   compaction_throughput_mb_per_sec: 16
   compaction_preheat_key_cache: true


I aborted Cassandra after a timeout query;
my Cassandra is 1.2beta-2
I don't what hardware information may help


On Mon, Oct 15, 2012 at 11:19 PM, Michael Kjellman <mkjellman@barracuda.com> wrote:
And to clarify my reply, this was a loop in compactions on system-schema_columns specifically.

From: Michael Kjellman <mkjellman@barracuda.com>
Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Date: Monday, October 15, 2012 8:11 AM
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Subject: Re: Why my Cassandra is compacting like mad

I had a similar bug with 1.1.5 but I couldn't reproduce it so I didn't file a bug. I did a rolling restart of my nodes and things went back to normal.

From: Manu Zhang <owenzhang1990@gmail.com>
Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Date: Monday, October 15, 2012 8:02 AM
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Subject: Why my Cassandra is compacting like mad

My Cassandra is compacting like mad (look at the following messages) after I restart it after a timeout query. It won't stop until I kill the process. 


INFO 22:57:41,839 Compacting [SSTableReader(path='/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1258-Data.db')]
 INFO 22:57:42,077 Compacted to [/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1259-Data.db,].  4,377 to 4,377 (~100% of original) bytes for 3 keys at 0.017539MB/s.  Time: 238ms.
 INFO 22:57:42,079 Compacting [SSTableReader(path='/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1259-Data.db')]
 INFO 22:57:42,309 Compacted to [/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1260-Data.db,].  4,377 to 4,377 (~100% of original) bytes for 3 keys at 0.018149MB/s.  Time: 230ms.
 INFO 22:57:42,311 Compacting [SSTableReader(path='/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1260-Data.db')]
 INFO 22:57:42,574 Compacted to [/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1261-Data.db,].  4,377 to 4,377 (~100% of original) bytes for 3 keys at 0.015872MB/s.  Time: 263ms.
 INFO 22:57:42,576 Compacting [SSTableReader(path='/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1261-Data.db')]
 INFO 22:57:42,814 Compacted to [/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1262-Data.db,].  4,377 to 4,377 (~100% of original) bytes for 3 keys at 0.017539MB/s.  Time: 238ms.
 INFO 22:57:42,816 Compacting [SSTableReader(path='/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1262-Data.db')]
 INFO 22:57:43,070 Compacted to [/home/manuzhang/cassandra/data/system/schema_columns/system-schema_columns-ia-1263-Data.db,].  4,377 to 4,377 (~100% of original) bytes for 3 keys at 0.016434MB/s.  Time: 254ms.

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