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From "Terry P." <>
Subject Re: Sizing walog area
Date Thu, 24 Oct 2013 16:58:40 GMT
Hi Christopher,
Just to ensure I'm looking at the correct property, by "in-memory map size
per tserver" are you referring to the property *tserver.memory.maps.max* in
*accumulo-site.xml*?  If that's the case, I'm using 1GB for that property.

I am running loggers on each tserver. Is the default that Accumulo writes
to at least two loggers?  I see config item *
logger.recovery.file.replication* is set to 2 (by default); is that what
controls this?

Digging around, I also see that logger.archive.replication is set to 2, and
logger.archive is false.  What does logger.archive and
logger.archive.replication do?  I find no mention of "archive" in the User

Many thanks Christopher, your help is always appreciated.

On Wed, Oct 23, 2013 at 2:10 PM, Christopher <> wrote:

> The data in the write-ahead logs is needed until the tserver flushes
> the in memory maps to disk. Assuming you have a logger running on
> every tserver, and tservers write to at least two loggers, you should
> ensure that the size of the disk area is *at least* two times as big
> as your in-memory map size per tserver. I'd say 5x-10x the in-memory
> map size is probably safe. So, if your tservers are running with 2GB
> of memory, then a 10-20GB area is probably more than sufficient.
> --
> Christopher L Tubbs II
> On Wed, Oct 23, 2013 at 1:02 PM, Terry P. <> wrote:
> > Greetings all,
> > For Accumulo 1.4 where write ahead logs are not yet stored in HDFS, does
> > anyone have guidancewith respect to sizing the walog area?  What exactly
> > triggers when write ahead logs get removed?  What might cause them to
> hang
> > around for an extended period of time (as in under abnormal
> circumstances)?
> >
> > The system this applies to will see an ingest rate of approximately 2000
> > docs per second averaging 1-2K each (broken out into 12 columns each, so
> > 24,000 entries per second) across 6 tabletserver nodes.
> >
> > Thanks in advance,
> > Terry

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