It is normal for disk usage to double. Under controlled circumstances,
it can triple, but that probably won’t happen.

This is the second time today that I’ve sent this information to the list.

It can use nearly 2X the space whenever the largest segment(s) are
merged, especially if there are only a few smaller segments.

In order to use 3X the space, you need to:

1. Disable merging.
2. Delete all the documents.
3. Add all the documents.
4. Enable merging.

This causes one complete set of segments that are 100% deletes,
one set that is 0% deletes, then the merge creates another set that
is 0% deletes. During the merge, the old files remain while the
new one is created.

wunder
Walter Underwood
wun...@wunderwood.org
http://observer.wunderwood.org/  (my blog)


> On Oct 28, 2016, at 2:41 PM, Alexandre Rafalovitch <arafa...@gmail.com> wrote:
> 
> 2) Is probably a merge operation. Lucene index segments are not
> rewritable in place, so the merge creates a new file, does everything
> to it, then switches to it.
> 
> I remember the number was that the space could temporarily triple
> (?!?) though that may have been before the tiered merge policy.
> 
> 3) It should be safe to delete old log files. It is standard log4j stuff.
> 
> ----
> Solr Example reading group is starting November 2016, join us at
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> 
> 
> On 29 October 2016 at 06:55, Jamal, Sarfaraz
> <sarfaraz.ja...@verizonwireless.com.invalid> wrote:
>> Hi Guys,
>> 
>> I am currently investigating an instance of Solr's Disk space usage and I 
>> had a few questions I thought you guys might be able to help answer.
>> 
>> First Question
>> * There is 30 gb's worth of autosuggest data in the /tmp folder. Each file 
>> is half of a gigabyte
>> Is it safe to delete those files?
>> 
>> Second Question
>> Also, we notice that at times the disk runs down to only having a few 
>> gigabytes available, and then goes back to having more space. (the index 
>> file literally grows and then shrinks).
>> 
>> Third Question
>> Is it also safe to delete the log files?
>> 
>> We run a database indexer on a set interval, perhaps that is relevant to 
>> this discussion.
>> 
>> Sas

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