负载均衡下设置Session需要注意的一点，防止Session丢失

http://technet.microsoft.com/en-us/library/cc780248.aspx
Preserving Session State with ASP.NET Web Applications in Network Load Balancing
Updated: August 22, 2005

If you use SqlServer or StateServer session state mode, session state might be lost when you run an ASP.NET Web application in a Network Load Balancing server cluster. To maintain session state across different Web servers in the cluster, the application path of the Web site (for example, \LM\W3SVC\2) in the IIS metabase must be the same for all of the Web servers in the cluster.

On one Web server, the instance ID of the Web site where the ASP.NET application is hosted might be 1 (where the application path is \LM\W3SVC\1). On another Web server, the instance ID of the Web site might be 5 (where the application path is \LM\W3SVC\5).

负载均衡下需要把不同机器上站点的instance ID都设为同一个。否则session会丢失，即使你把session设为了保存在sqlserver。

需要运行如下脚本

MySitesIdList.vbs

Function ProcessWebSite(ServiceType, SiteNumber)

Set IISWebSite = getObject("IIS://localhost/" & ServiceType & "/" & SiteNumber)

Set IISWebSiteRoot = getObject("IIS://localhost/" & ServiceType & "/" & SiteNumber & "/root")

ProcessWebSite = IISWebSite.ServerComment

Set IISWebSiteRoot = nothing

Set IISWebSite = Nothing

end function

Function ShowSites(ServiceType, ClassName, Title)

Wscript.echo "Web Sites Description"

Wscript.echo "==============================================================="

Set IISOBJ = getObject("IIS://localhost/" & ServiceType)

for each Web in IISOBJ

if (Web.Class = ClassName) then

wscript.echo Ucase(ServiceType) & "/" & Web.Name & _

Space(17-(len(Ucase(ServiceType))+1+len(Web.Name))) & " " & _

ProcessWebSite(ServiceType, Web.name)

end if

next

Set IISOBj=Nothing

WScript.Echo ""

End function

Call ShowSites("w3svc", "IIsWebServer", "Web")

把脚本考到机器上然后运行cscript MySitesIdList.vbs

Dim WebService

Dim oldstr

Dim newstr

Dim args

Set args = WScript.Arguments

If args.Count < 1 Then

Wscript.Echo "Must have original instance id and new instance id" & chr(10) & chr(13) & _

"usage: moveinstance.vbs 1 5" & chr(10) & chr(13) & _

"Moves instance 1 to instance 5"

WScript.Quit()

End If

Set WebService = GetObject("IIS://LocalHost/W3SVC")

oldstr = args(0) 'old instance

newstr = args(1) 'new instance

WebService.MoveHere oldstr,newstr

WebService.SetInfo

Set WebService = nothing

Set args=nothing

WScript.echo "DONE"

运行

cscript ChangeSiteId.vbs 1 5

and then press ENTER. Instance ID就从1改到了5.