Newbie datacenter lesson #2: Performance considerations

So you are finally doing it!  Moving everything to a colo site - so exciting! So much redundant input power!  So much reliable A/C!

So much latency between sites.

It made so much sense to move EVERYTHING over that the only consideration you gave any thought to was DFS/Folder Redirection (which does, indeed, stink over the WAN).  One other small fuzzy area you forgot about was AccPac (Sage ERP 200).

DFS/Folder Redirection - at least this was a known potential issue.  It's slow, but users can live with it if they must (and $ dictates wait they must).  But AccPac!  It's so un-useable at this point that immediate measures must be taken.

Latency, you ask - how awful is it?  27ms.  (both sites on 100mb fiber)

Yep, 27ms is enough to bring AccPac to its knees.  It turns out that AccPac is a rather old application, and has a neat feature called 'DBspy' that displays its age nicely.  If you watch the 'DBspy' monitor screen, simply clicking on a single widget-thing in AccPac yields dozens of SQL calls.  It's no wonder the entire app is slow now!  Going from <1ms to 27ms is a fairly significant multiplier.

Speaking with our AccPac rep, he informed us that what we are trying to do (workstations connecting to remote SQL) is not a good idea, and we have two alternatives:

  1. Move the server back.
  2. Set up terminal services/appServer at the colo, have the users connect via RDP/remoteApp instead.
I don't really want to mess with the finance folks' workflow, so local server it is.  Thankfully we only have 15-20GB of databases to move.  Does mean one more SQL Standard license to purchase, however.  Good thing we left that single Hyper-V box behind for domain controllers...

So the lesson is: Check with ALL of your vendors and review the planned changes with them, especially the legacy providers.


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