Hi, 1 GiB is the maximum possible. The chunk size is only applicable for 32 bit JDKs because of limited address space.
Uwe ----- Uwe Schindler H.-H.-Meier-Allee 63, D-28213 Bremen http://www.thetaphi.de eMail: u...@thetaphi.de > -----Original Message----- > From: Gaurav gupta [mailto:gupta.gaurav0...@gmail.com] > Sent: Friday, September 26, 2014 9:12 PM > To: java-user@lucene.apache.org > Subject: Optimum Lucene’s MMapDirectory size on 64bit OS > > Hi, > > As per the post "The Generics Policeman Blog > <http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on- > 64bit.html>" > , I am using the MMapDirectory for faster access(search and update > operations ,mainly search) of Lucene 4.8.1 index files. I am contemplating > what is the optimal maximum MMap value for my indexes. Is default i.e. 1 > GB > (1 << 30) or higher? > > I have 6 indexes of size varying from 65GB to 6 GB. Currently, I am using 1 GB > as maxChunkSize : - *MMapDirectory(file, null, 1<<30) *for all indexes. > But thinking of specifying the higher value for mmap (1 GB or higher) for > bigger index having 65GB size and lower value (0.5 GB or less) for smaller > index having size of 6 GB. Any suggestion/guidance on it ? > > Also, per blog mmap is not a size of physical memory allocation but just a > address space to map the index files. How to allocate more RAM to index > files for better performance? We have enough RAM free out of 64 GB. Per > blog, one should use the mmap file, like - *MMapDirectory(file, null, > 1<<30) *and let OS manage the physical memory allocation for the index > files. Is my understanding correct ? > > The Generics Policeman Blog > <http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on- > 64bit.html> :- > > - *MMapDirectory does not consume additional memory and the size of > mapped index files is not limited by the physical memory available on your > server.* By mmap() files, we only reserve address space not memory! > Remember, address space on 64bit platforms is for free! > > Thanks > Gaurav --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
