Solr 1.4 is doing great with respect to Indexing on a dedicated physical server (Windows Server 2008). For Indexing around 1 million full text documents (around 4 GB size) it takes around 20 minutes with Heap Size = 512M – 1G & 4GB RAM.
However while using Solr on a VM, with 4 GB RAM it took 50 minutes to index at the first time. Note that there is no Network delays and no RAM issues. Now when I increased the RAM to 8GB and increased the heap size, the indexing time increased to 2 hrs. That was really strange. Note that except for SQL Server there is no other process running. There are no network delays. However I have not checked for File I/O. Can that be a bottleneck? Does Solr has any issues running in “Virtualization” Environment?
I read a paper today by Brian & Harry: “ON THE RESPONSE TIME OF A SOLR SEARCH ENGINE IN A VIRTUALIZED ENVIRONMENT” & they claim that performance gets deteriorated when RAM is increased when Solr is running on a VM but that is with respect to query times and not indexing times.
I am bit confused as to why it took longer on a VM when I repeated the same test second time with increased heap size and RAM.
I/O on a VM will always be slower than on dedicated hardware. This is because the disk is virtualized and I/O operations must pass through an extra abstraction layer. Indexing requires intensive I/O operations, so it’s not surprising that it runs more slowly on a VM. I don’t know why adding RAM causes a slowdown though.