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From William Slacum <wilhelm.von.cl...@accumulo.net>
Subject Re: Uneven distribute of Hosted Tablets?
Date Fri, 31 May 2013 14:14:04 GMT
You could also lower the split threshold (do a `config -t <table>` and
you'll see a parameter with a similar name) and then compact the table.

How are you ingesting data? I believe that adding monotonically increasing
keys can lead to a pattern where only the last tablet is being added to and
split (not 100% on this). If you know some distribution for the keys you're
adding, it might be a good idea to add split points to the table to
increase parallelism.


On Fri, May 31, 2013 at 10:00 AM, Ott, Charles H. <CHARLES.H.OTT@saic.com>wrote:

> I performed a clean shutdown and startup of all the processes using the
> start-all.sh/stop-all.sh scripts.****
>
> ** **
>
> The systems have only been online for about 5 minutes and everything is
> working.  But I see the following Recent WARN in the Logs:****
>
> ** **
>
> time
> application                          count    level      message****
>
> 31 09:37:57,0774               tserver:1620-accumulo  1
> WARN   Future location is not to this server for the root tablet****
>
> ** **
>
> Hosted tablet distribution seems to be worse:****
>
> ** **
>
> (Image Below Here)****
>
>
> (Image Above Here)****
>
> ** **
>
> I am able to login and scans seems to be responsive.   I noticed that when
> we had our entries ~20 M count, our batch scans were taking much longer.  I
> was hoping that by distributing the tablets evenly, and splitting some of
> the bigger tables, we could get better performance.
>
> ****
>
> As for splitting the bigger table, I received a message from a peer.  He
> mentioned that I could create a new table and split it on the values I
> want.  Then use Map reduce job to move the data from the single tablet
> table to split table.  ****
>
> ** **
>
> *From:* user-return-2638-CHARLES.H.OTT=saic.com@accumulo.apache.org[mailto:
> user-return-2638-CHARLES.H.OTT=saic.com@accumulo.apache.org] *On Behalf
> Of *John Vines
> *Sent:* Thursday, May 30, 2013 5:30 PM
> *To:* user@accumulo.apache.org
> *Cc:* Lahr-Vivaz, Emilio F.
>
> *Subject:* Re: Uneven distribute of Hosted Tablets?****
>
> ** **
>
> Your distribution is cause for concern. I thought we had resolved a lot of
> the balancer issues in 1.4.1 or 1.4.2. Are you seeing any errors from the
> master in your logs? Worst case scenario is you just have to kill the
> master process and start it back up and you should see things balancing out.
> ****
>
> ** **
>
> On Thu, May 30, 2013 at 4:40 PM, Ott, Charles H. <CHARLES.H.OTT@saic.com>
> wrote:****
>
> Thanks for the feedback.  I will keep what you said in mind.****
>
>  ****
>
> *From:* user-return-2636-CHARLES.H.OTT=saic.com@accumulo.apache.org[mailto:
> user-return-2636-CHARLES.H.OTT=saic.com@accumulo.apache.org] *On Behalf
> Of *David Medinets
> *Sent:* Thursday, May 30, 2013 4:34 PM
> *To:* accumulo-user
> *Subject:* Re: Uneven distribute of Hosted Tablets?****
>
>  ****
>
> Don't worry about splits until you have a few billion entries and a lot
> more servers. What you're seeing now is just a bad signal to noise ratio.*
> ***
>
>  ****
>
> On Thu, May 30, 2013 at 11:22 AM, Ott, Charles H. <CHARLES.H.OTT@saic.com>
> wrote:****
>
> First I want to say thanks to the you all.  The information provided by
> this mailing list has been invaluable to me and I appreciate it.****
>
>  ****
>
> My newest concern is the uneven allocation of hosted tablets across my
> tablet servers:****
>
>  ****
>
> (Image Pasted below here)****
>
> ****
>
> (Image Pasted above here)****
>
>  ****
>
> I have been reading about pre-splitting tables in the Accumulo guide.  But
> I am not sure if that would be the ‘fix’ for this.  (Or even if this needs
> fixing.)****
>
>  ****
>
> I have 3 tables that could potentially grow to *n* number of records.
> Currently of those tables (and there single tablet) reside on the
> 1620-accumulo server (Hosting 24 tablets).****
>
>  ****
>
> Since there is already several entries on those tables, would splitting
> them be appropriate?  Does splitting guarantee that the new tablets will be
> allocated to Node1 instead of Node 3? Or perhaps could I “re-balance” the
> cluster so that all of the tablet servers host an approximately equal
> number of tablets?****
>
>  ****
>
> These tablet servers were all brought up at separate times and I have not
> performed any optimizations or custom operations on them.****
>
>  ****
>
>  ****
>
> Thanks,****
>
> Charles****
>
>  ****
>
>  ****
>
>  ****
>
> ** **
>

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