INTRODUCTION

I'm currently working at a client site who has the following Sharepoint Intranet farm configuration:
- 2 Web Front End (WFE) servers
- 1 Central Admin server
- 1 Indexing server
- 1 Database

There is a load balancer that should balance the load between the 2 WFE however it doesn't work properly. Somehow, the load balancer always points to the first WFE. Therefore, if you access http://intranet/ it always points to the first WFE.

The Intranet works OK everyday until one point few months ago it started to return the incorrect version of the document. For example, you upload a document and check-in as version 0.1. When you navigate to the document via the URL directly (eg. http://intranet/DocumentLibrary/MyDoc.doc) it returns you version 0.1 which is correct. Then you upload a new version of the document, override the old version and check-in to become version 0.2. Now, when you navigate directly to the URL of the document, somehow Sharepoint returns it with version 0.1. What's strange is, this only happens on the first WFE. If you force-point http://intranet/ to the second WFE via editing HOSTS file, you get the correct version of the document!

We have looked at this problem for quiet some time now and we finally resolve it after few weeks of investigation. We know that there must be something different (configuration, etc) on first WFE compared to the second one because the second WFE always returns the correct version of the document. Therefore, this is what we've done:
- Checking and comparing IIS settings
- Checking and comparing web.config settings
- Checking Sharepoint cache settings
- Checking load balancer cache settings
- Checking the actual document data in SP database! Yep, we actually went into Sharepoint DB and looked for that particular document in AllDocs table and the data that is stored in the DB is actually correct (ie. the newer version is stored correctly)

SOLUTION

So, what's the problem then? The DB clearly stores the latest version of the document so there is no reason for Sharepoint to return the incorrect version of the document. After further investigation we actually found out that the problem was actually with the BLOB CACHE settings! In web.config someone has turned on BLOBCACHE and somehow the cached documents in first WFE aren't synced with second WFE's. When we clear the BLOB CACHE folder of first WFE, it starts to return the CORRECT version of the document! So from this moment on, we will ensure that the blob cache folder content is synched between first WFE and second WFE.

If anyone has ever had the same problem, this may help.

Cheers,
Tommy