Several servers on one logical drive

[Christian Bieletzki]

Hi,

is there a way to allow several servers (that host small services like blackberry or other small database servers) to access one logical drive in the SAN. My intention is to spare two drives in the MSA enclosure, mirror them and then allow all servers I need to access them by setting the permissions on the selective storage presentation.


My intention is not to allow them to access the partition simultaneously. It should be one logical drive in the MSA (for the mirriring) Then I want to place several partitions on it in windows 2003 server. Each server should access only it's partition.

If that's not possible why do I have then the possibility to assign more than one device access to over ssp (is this only for servers in clustering configuration)

Kind regards

Christian

[andy steven · Accepted solution]

Hi

U are right u can only present a lun to two or more servers for clustering.

Data curruption may occur if two servers are writing to the same lun.

hope this helps

[Uwe Zessin]

You can "partition" a disk array[*] by creating multiple logical drives at the controller level. Then you can define which server has access to which 'part of the disk arry'. Just remember that:

- the MSA supports a maximum of 32 logical drives

- you can delete logical drives only in reverse order from a disk array


[*] 'disk array' here does not mean the entrie MSA, but a controller-based array made of multiple physical disk drives.

[andy steven]

Hi

I agree the logical creation and presentation of logical disks can be done at the controller level and servers given access via SSP, however, and correct me if i am wrong but what was suggested was to create on big array and one big logical disk at the controller level, then give all servers access to this logical disk but then use windows disk manager to create small logical partitions for each server (i think this would be dangerous and result in data curruption) i may have misunderstod Christians question though.

andy

[Uwe Zessin]

I have understood what was asked, but due to Windows by default mounting any file systems it sees, this is "unsafe at any speed". And even on other operating systems I would avoid it - I first got burned by this around 1987/88 when somebody mounted a disk from a storage controller (DEC HSC50) that he thought was not in use.

[Danny Loria_1]

The simple answer is , no. The only time you would ever give two hosts access to the same LUN is a cluster.
On an EVA you can give a second host "read-only" access for backup purposes, but on the MSA this is not an option.

[Uwe Zessin]

As far as I know, Windows requires read/write access to be able to mount an NTFS volume.

[Steven Clementi]

Christian:

Unfortunately, you can not do that. As Uwe suggests, and probably the best course of action, create 1 large array and several small luns as needed for the different servers. You can assign the hosts to them via SSP.

In order to minimize downtime later on, I would create the logical units as small as possibly needed and later increase them in size. Since you can not decrease the size of a logical unit nor can you delete say... LUN2 when there is a LUN3 in the same array, it would be easier to increase the size of the lun later rather than re-configuring the lun you need AND all the luns after it.

Using diskpart.exe, you can safely and effectively increase the partition within Windows once you increase the lun size.

As far as I can remember, mounting a read only vdisk from an EVA onto a Windows Server caused no problems and worked flawlessly. I could be wrong or it could have changed. I did this maybe once or twice in the past in a test environment.


Steven