Advanced Disk

[AlGon]

Netbackup 7.0.1, Windows 2003 Server

Hello

I'm reading up on a few bits in the Shared Storage Guide and have a basic query regarding Advanced Disk.

I'm after some confirmation;

If for example I have two media servers SAN attached to some storage.  Can I share a single LUN between them to use as backup storage?

Can both Media servers write to this storage at the same time?

My understanding is for this basic setup is:

1. I could create a single Advanced disk pool
2. Select both media servers as storage servers 
3. Select the shared LUN
4. Create a storage unit and select both media servers

Thanks

[RiaanBadenhorst]

Hi,

The shared disk option has been dropped in 7.0. Strangely enough i saw another reference to Shared Disk under the advanced disk section in the SSO guide. It does however state this....

If you do so, be aware of the following:
■    Each media server must mount the file systems of all the disk volumes within a disk pool.

Now on windows, you're not going to be able to mount an NTFS file system on two system at the same time. So I'm assuming that this must be referring to a NAS / CIFS mount.

If you're running UNIX/LINUX and you've got a shared (cluster) file system such as CFS from Symantec I suppose that would also work. Documentation seems a bit vague to me, but I do think they're talking about NAS.

[Nicolai]

I share the same understanding as Riaan regarding the topic.

I used a long time reading the manual over and over to understand what they meant. Seems the manual is trying to cover both normal access and shares access in the same two pages, but is missing to mention when concurrent access can happen.

[AlGon]

Thanks for the reponses

Hmm, I'm a little confused now. 

I thought that once this is setup, having an advanced disk pool might somehow control access to the shared disk, so as to make it possible for two servers to access an NTFS file system at the same time.

I've got a test environment (simple VMware setup) so perhaps I could somehow setup a Linux box as an NFS server and use is as my shared disk.

Cheers

[Nicolai]

Netbackup Shared Disk allowed LUN to be mount and dismounted just like tape (that's properly what you wanted). But the solution was to vulnerable for firmware changes so it was removed in NBU 7.x

[RiaanBadenhorst]

WOW, I never new that. Coming from a cluster background I saw shared disk and thought it would be some implementation of clustered disk where both servers had it mounted as the same time (as i believe the case is with the advanced disk shared option) and writing to it.

What you describe sounds like a VTL with potentially only one, or two, very big cartridges in it, LOL

[alazanowski]

Now, with advanced disk, you can have another media server write to the same advanced disk pool, but it would be routed through the server that has access to it as a mountpoint, so it makes it generally moot performance wise unless you have something like an infiniband backbone between the two systems.

[AlGon]

Hi alazanowski

Are you saying that I could possibly set up two media servers as storage servers in the same advanced disk pool, but only one media server would have read\write access to the storage (weather it be a NTFS LUN or NAS device) and the other would just be used to load balance the incoming data which is then passed onto the media server with the attached storage? 

Thanks

[Nicolai]

you can do it with a NAS device but not NTFS LUN using advanced disk. You can't have concurrent access to a LUN unless you use a file system designed for this e.g. Symantec Cluster File System.

[AlGon]

Hi Nicolai,

OK,  Would I be able to test this with something like FreeNas - http://freenas.org/ . I'm not overly familiar with NAS devices.

I've setup freeNAS in my test environment and connected it to my media servers via ISCSI.  The problem being that as soon as each windows server detects the disks it wants to format them using NTFS :(.  Wouldn't this be the same for any NAS device attached to a windows box?

Cheers

[Nicolai]

I haven't played around with freenas, but remember that "normal" iSCSI LUN's also need exclusive access from one host. CIFS mount'ts may work, but I recall a tech note some time ago claiming CIFS mount is not compatible with AdvancedDisk.

[AbdulRasheed · Accepted solution]

It is possible to use AdvancedDisk with multiple media servers if the backend file system allows concurrent mounting. Concurrent mounting is possible with Cluster File System and NFS/CIFS file systems.

The requirement to configure AdvancedDisk this way requires all media servers to use the same mount point for the shared file system. The you need to run nbdevconfig to make some changes to storage server attributes.

An example of setting up concurrent access to the same AdvancedDisk volume using SFCFS is given here: http://www.symantec.com/docs/TECH68582

Warm regards,

Rasheed

[Nicolai]

Shared Storage Guide page 27 say:

Windows CIFS not supported
On Windows, networked mapped devices are not visible to Windows services, and
AdvancedDisk cannot discover Common Internet File System disk volumes.
Therefore, AdvancedDisk does not support the Common Internet File System.

Has this changed since the manual was written ?

[AlGon]

Sorry for the late response.

Thanks Nicolai for all your help on this one :).  

[AlGon]

OK, thanks Rasheed.

Could you clarify Nicolais query regarding weather or not CIFS mounting is supported?

Thanks

[AbdulRasheed]

Hi guys,

   CIFS is supported since NetBackup 7.0.1. Please see http://www.symantec.com/docs/HOWTO34525

Warm regards,

Rasheed

[AbdulRasheed]

Sorry I meant to say since NetBackup 7.0.1 in the subject line above.