Index Server Group servers Virtual or not?

[GertjanA]

Hello all, seeking experience..

Does anyone use Index Server Group with index servers being virtual machines? If so, is this a large environment? What is your experience with this? Would you do it again, or would you use the 'old' configuration (storage and indexing on same server)?

Thanks for insights!

GJ

[daveoflave]

This first post went up accidentally without the intended text, sorry!

[daveoflave · Accepted solution]

Hi Gertjan,

   Well most of what I'd explain about indexing is probably stuff you already know, but I can share my experiences.  And I'd have to be careful in answering because it's possible to have EV1 be the "indexer" for a vault store on EV2, without it being in an "Index Server Group."

   In my experience working in customer environments who've done similar things, it never came to a question of having a server group/not having a server group.  Rather the bigger question was virtualization. Our indexing white paper cites a 25% drop in search peformance when comparing the same hardware in virtual vs physical machines; ballpark.  But that's not necessarily index-ingestion rates; that only mentions search.

     So the group part; I've never seen it affect anything in my cases - it's just a nightmare to dtrace the right server when indexing problems come into play.  But for the peformance in the environment, having a group never impacted indexing speed in my cases.

    I did have a few cases where customers in large EV sites migrated all EV servers to virtual machines and did have a marked decrease in indexing speeds; though it was still enough to keep up in their busy environments. 

    Also of course; the velocity engine practically lives in pagefile, so if it has plenty of room, it's usually still ok on virtual.  I always advise the old "pagefile should be 2x physical memory" rule, and it's served us well.  So on that note; virtual seems fine to me, as long as it has the specs (likely better specs than its physical counterpart) can handle the work load.

    But in an attempt to specifically answer your question:  Yes, I've had cases in which large EV sites had Index Server Groups on VM's, and it worked ok.  It just had high resource requirements from the host machines.  Me though, as a troubleshooting engineer, I always like your "old" configuration you mentioned, but that's just because it's easier to chase problems.  Index Server Groups work ok, but can be logistical nightmare for the admin when problems arise. Virtual works ok, but you just have to beef up the resources to the VM's. 

Never had a case in which I wished the servers weren't virtual though. 

[GertjanA]

Hello Dave,

Thanks! I know of the troubleshooting nightmare (no comment...) but I am glad to hear you did not run in major trouble. I was not here when the environment was designed, so I assume the original architect listened to the advice, and had the ISG consitst of physical servers. The others are VM's, and performance is now (after months of tweaking) well.

I'll keep your comments in the back of my head, as I might need to do a redesign.

Thanks for your extensive answer, very helpfull!

GJ