Thanks for the information. I thought backup is going to be more of the disk activity. But I understand now that RAM is involved here as well. We indeed did NOT have enough memory in this box, as it is 64GB box with index size of 72GB, being backed up. The read (real time GET) performance was better without BACKUP, could be because there was minimal disk access, but with Backup running, reads (GET) are probably doing disk read for every request.
Thanks, Ganesh On Tue, Sep 18, 2018 at 3:43 PM Shawn Heisey <apa...@elyograg.org> wrote: > On 9/18/2018 11:00 AM, Ganesh Sethuraman wrote: > > We are using Solr 7.2.1 with SolrCloud with 35 collections with 1 node ZK > > ensemble (in lower environment, we will have 3 nodes ensemble) in AWS. We > > are testing to see if we have Async Solr Cloud backup ( > > https://lucene.apache.org/solr/guide/7_2/collections-api.html#backup) > done > > every time we are create a new collection or update an existing > collection. > > There are 1 replica and 8 shards per collection. Two Solr nodes. > > > > For the largest collection (index size of 80GB), we see that BACKUP to > the > > EFS drive takes about ~10 mins. We are doing lot of /get (real time get) > > option from the application. We are seeing that that the performance > > significantly (2x) degrades on the read (get) performance when we BACK-UP > > is going on in parallel. > > My best guess here is that you do not have enough memory. For good > performance, Solr is extremely reliant on having certain parts of the > index data sitting in memory, so that it doesn't have to actually read > the disk to discover matches for a query. When all is working well, > that data will be read from memory instead of the disk. Memory is MUCH > MUCH faster than a disk. > > Making a backup is going to read ALL of the index data. So if you do > not have enough spare memory to cache the entire index, reading the > index to make the backup is going to push the important parts of the > index out of the cache, and then Solr will have to actually go and read > the disk in order to satisfy a query. > > https://wiki.apache.org/solr/SolrPerformanceProblems#RAM > > Can you gather a screenshot of your process list and put it on a file > sharing website? You'll find instructions on how to do this here: > > > https://wiki.apache.org/solr/SolrPerformanceProblems#Asking_for_help_on_a_memory.2Fperformance_issue > > Thanks, > Shawn > >
