I am only using LeveledCompactionStrategy, and as I describe in my original 
mail, I don’t understand why C* is complaining that it cannot compact when I 
have more than 40% free disk space.



On 07 Apr 2015, at 01:10 , Bryan Holladay 
<holla...@longsight.com<mailto:holla...@longsight.com>> wrote:


What other storage impacting commands or nuances do you gave to consider when 
you switch to leveled compaction? For instance, nodetool cleanup says

"Running the nodetool cleanup command causes a temporary increase in disk space 
usage proportional to the size of your largest SSTable."

Are sstables smaller with leveled compaction making this a non issue?

How can you determine what the new threshold for storage space is?

Thanks,
Bryan

On Apr 6, 2015 6:19 PM, "DuyHai Doan" 
<doanduy...@gmail.com<mailto:doanduy...@gmail.com>> wrote:

If you have SSD, you may afford switching to leveled compaction strategy, which 
requires much less than 50% of the current dataset for free space

Le 5 avr. 2015 19:04, "daemeon reiydelle" 
<daeme...@gmail.com<mailto:daeme...@gmail.com>> a écrit :

You appear to have multiple java binaries in your path. That needs to be 
resolved.

sent from my mobile
Daemeon C.M. Reiydelle
USA 415.501.0198<tel:415.501.0198>
London +44.0.20.8144.9872<tel:%2B44.0.20.8144.9872>

On Apr 5, 2015 1:40 AM, "Jean Tremblay" 
<jean.tremb...@zen-innovations.com<mailto:jean.tremb...@zen-innovations.com>> 
wrote:
Hi,
I have a cluster of 5 nodes. We use cassandra 2.1.3.

The 5 nodes use about 50-57% of the 1T SSD.
One node managed to compact all its data. During one compaction this node used 
almost 100% of the drive. The other nodes refuse to continue compaction 
claiming that there is not enough disk space.

From the documentation LeveledCompactionStrategy should be able to compact my 
data, well at least this is what I understand.

<<Size-tiered compaction requires at least as much free disk space for 
compaction as the size of the largest column family. Leveled compaction needs 
much less space for compaction, only 10 * sstable_size_in_mb. However, even if 
you’re using leveled compaction, you should leave much more free disk space 
available than this to accommodate streaming, repair, and snapshots, which can 
easily use 10GB or more of disk space. Furthermore, disk performance tends to 
decline after 80 to 90% of the disk space is used, so don’t push the 
boundaries.>>

This is the disk usage. Node 4 is the only one that could compact everything.
node0: /dev/disk1 931Gi 534Gi 396Gi 57% /
node1: /dev/disk1 931Gi 513Gi 417Gi 55% /
node2: /dev/disk1 931Gi 526Gi 404Gi 57% /
node3: /dev/disk1 931Gi 507Gi 424Gi 54% /
node4: /dev/disk1 931Gi 475Gi 456Gi 51% /

When I try to compact the other ones I get this:

objc[18698]: Class JavaLaunchHelper is implemented in both 
/Library/Java/JavaVirtualMachines/jdk1.8.0_40.jdk/Contents/Home/bin/java and 
/Library/Java/JavaVirtualMachines/jdk1.8.0_40.jdk/Contents/Home/jre/lib/libinstrument.dylib.
 One of the two will be used. Which one is undefined.
error: Not enough space for compaction, estimated sstables = 2894, expected 
write size = 485616651726
-- StackTrace --
java.lang.RuntimeException: Not enough space for compaction, estimated sstables 
= 2894, expected write size = 485616651726
at 
org.apache.cassandra.db.compaction.CompactionTask.checkAvailableDiskSpace(CompactionTask.java:293)
at 
org.apache.cassandra.db.compaction.CompactionTask.runMayThrow(CompactionTask.java:127)
at org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:28)
at 
org.apache.cassandra.db.compaction.CompactionTask.executeInternal(CompactionTask.java:76)
at 
org.apache.cassandra.db.compaction.AbstractCompactionTask.execute(AbstractCompactionTask.java:59)
at 
org.apache.cassandra.db.compaction.CompactionManager$7.runMayThrow(CompactionManager.java:512)
at org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:28)

I did not set the sstable_size_in_mb I use the 160MB default.

Is it normal that during compaction it needs so much diskspace? What would be 
the best solution to overcome this problem?

Thanks for your help


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