That is correct, but twice the disk space is theoretically not enough. Worst case is actually three times the storage, I guess this worst case can happen if you also submit new documents to the index while optimizing. I have experienced 2.5 times the disk space during an optimize for a large index, it was a 1TB index that temporarily used 2.5TB disc space during the optimize (near the end of the optimization).
From, Thomas Egense On Wed, Jun 25, 2014 at 8:21 PM, Markus Jelsma <markus.jel...@openindex.io> wrote: > > > > > -----Original message----- > > From:johnmu...@aol.com <johnmu...@aol.com> > > Sent: Wednesday 25th June 2014 20:13 > > To: solr-user@lucene.apache.org > > Subject: How much free disk space will I need to optimize my index > > > > Hi, > > > > > > I need to de-fragment my index. My question is, how much free disk > space I need before I can do so? My understanding is, I need 1X free disk > space of my current index un-optimized index size before I can optimize it. > Is this true? > > Yes, 20 GB of FREE space to force merge an existing 20 GB index. > > > > > > > That is, let say my index is 20 GB (un-optimized) then I must have 20 GB > of free disk space to make sure the optimization is successful. The reason > for this is because during optimization the index is re-written (is this > the case?) and if it is already optimized, the re-write will create a new > 20 GB index before it deletes the old one (is this true?), thus why there > must be at least 20 GB free disk space. > > > > > > Can someone help me with this or point me to a wiki on this topic? > > > > > > Thanks!!! > > > > > > - MJ > > >
