Shared LUNs

[ambankiowa]

I know that Shared LUNs are supposed to be used only for clustered servers.  I'm curious to know why I couldn't use a shared LUN for 2 independent servers that will be interacting with 2 completely different directory structures.

My situation:  I have a mail archive service that is split into 2 separate servers.  One server houses the database and one server houses the indexes.  I would like to be able to store the indexes and the databases in the same LUN rather than carve out separate LUNs for each.  Is there a technical problem with doing that aside from it not being recommended.  I'm guessing that the recommendation/requirement is based on the fact that you have no way to lock files between two separate servers and could run into data corruption issues.  Am I correct in that assumption?

Is there another option that will allow me to use snapdrive and have more than one server connected to a storage unit? (particularly because these are system services so someone may or may not be logged on to that particular server)

Thanks for any input.

Adam

[bsti]

You are correct that the you would run into data corruption if you had the same LUN attached to multiple servers with no software-level locking (like VMWare, MSCS, etc...) to prevent simultaneous file access. 

Have you considered hosting the data as a CIFS volume on the controllers?  We had a similar situation as yours come up and we decided the best/only way to allow multiple servers access without clustering software was hosting the data as a CIFS volume on a NetApp controller.

[ambankiowa]

I figured that was the case.  So, since that's the issue, is there any reason I couldn't share it anyhow since they won't be interacting with the same filesets?

I thought about CIFS but it adds one more level of complexity figuring domain credentials for access to the storage.  I don't want anyone else accessing it from the domain but don't want to have to set up domain credentials for those two servers and have to worry about them authenticating/etc.  Also, when services run as a local service (which is this archiving product) then domain credentials don't do much since the local service instance doesn't have any network privileges anyhow.

[shaunjurr]

Hi,

I was sort of hoping that this was NFS, then the situation is easy.  With Windows, there is no active-active sharing of LUN's anyway unless you use Veritas Cluster Server.  Windows 2008 can do NFS, so perhaps this is something to play with.  I can't attest to the quality of their NFS implementation, however.

Setting up a CIFS share to be access by a system user isn't that difficult, shares just need to be mapped with a crude "net share" batch script and the filer needs a few lines of configuration.  It would be an advantage if it was on an isolated/private (v)lan segment, of course.  We run a couple of pretty loaded Notes servers using CIFS shares and it is amazingly stable.  There used to be some documentation on NOW on how to set it up, but last I looked I couldn't find it.  I have a working implementation, so I have my documentation, in a way.