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From Anthony Molinaro <antho...@alumni.caltech.edu>
Subject Re: Multiple Data Directories
Date Thu, 25 Feb 2010 20:48:32 GMT
Okay, so the disk sizing seems to make sense for what I am seeing, the
disk which seems to get all the data is the largest.  On the new machines
which have 3 disks of equal size, compaction seems to be distributing
among the disks.

Raid0 would sort of defeat the purpose of being able to add additional
capacity on the fly (ie, adding ebs volumes to increase capacity), as
I need to know ahead of time what my configuration is.

The new boxes ended up with all the data files in one directory because
of the bug in 0.5.0 when bootstrapping with multiple directories which
I worked around by using one directory, bootstrapping, then adding
the other directories.

So when I have the situation of I just added an additional directory
with space equal to a current directory, is there any way to redistribute
the data files?  The operations page makes me think that maybe nodeprobe
repair might do it, will it?

Thanks,

-Anthony

On Thu, Feb 25, 2010 at 01:43:22PM -0600, Jonathan Ellis wrote:
> Compaction is why http://wiki.apache.org/cassandra/CassandraHardware
> recommends raid0-ing if you are concerned about free disk space
> limits.
> 
> On Thu, Feb 25, 2010 at 1:36 PM, Gary Dusbabek <gdusbabek@gmail.com> wrote:
> > Cassandra always compacts to the directory with the most free space.
> > There is not a way to influence this.
> >
> > Gary
> >
> > On Thu, Feb 25, 2010 at 13:23, Anthony Molinaro
> > <anthonym@alumni.caltech.edu> wrote:
> >> Hi,
> >>
> >>  So is there anyway to force distribution among DataFileDirectory entries
> >> when you add a new one?  Looking at the nodeprobe operations it seems like
> >> repair which causes a major compaction might do it?  I've tried shutting a
> >> node down moving files around by hand and starting up, but the next
> >> compaction seems to move everything back to a single directory?
> >>
> >>  I do see files show up in other directories as they are flushed, but
> >> then they all seem to make their way back to the first directory in the
> >> list.
> >>
> >> Thanks,
> >>
> >> -Anthony
> >>
> >> --
> >> ------------------------------------------------------------------------
> >> Anthony Molinaro                           <anthonym@alumni.caltech.edu>
> >>
> >

-- 
------------------------------------------------------------------------
Anthony Molinaro                           <anthonym@alumni.caltech.edu>

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