[CASSANDRA-1526] Make cassandra sampling and startup faster

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 0.6.6
• Assignee: Jonathan Ellis
• Reporter: Edward Capriolo

Authors

Jonathan Ellis

Reviewers

Stu Hood

• Created: 21/Sep/10 17:31
• Updated: 16/Apr/19 09:33
• Resolved: 04/Oct/10 16:11

Description

http://wiki.apache.org/cassandra/CassandraHardware makes mention of very large disks I do not see how that would be possible.

We have a server class system have 4x processors 16GB RAM a 6 DISK RAID5 (yes RAID0 would be faster but still)

INFO [main] 2010-09-21 12:58:26,348 SSTableReader.java (line 120) Sampling index for /var/lib/cassandra/data/system/LocationInfo-699-Data.db
...
INFO [main] 2010-09-21 13:05:51,333 CassandraDaemon.java (line 124) Binding thrift service to cdbsd07/10.71.71.57:9160

This node has 200GB of data in two column families and the time to sample all tables and startup is 7+ minutes. The logging suggests this process is happening a single SSTable at a time. Additionally the normal system vitals mainly DISK and CPU do not look overtaxed.

• Since SSTables are immutable is there a way the sampling of the tables could be saved?
• Could this process be done in parallel for speedup?
• Can multiple column families be processed at once?

Unless someone has an insanely powerful disk pack making mention of 2TB limitations seem out of place. Unless my calculations are wrong (which they usually are), I have a pretty decent hardware, and if I had 2 TB of data I would have a 95 minute node start up?

I hope that maybe sampling multiple ColumnFamilies at once would make nodes of at least a few hundred GB startup reasonably fast.