EVA: Is it possible to map a LUN to one Windows host as read/write and to a second one as read only?

[sam bell]

Hi

We are in the process of planning the migration from SAP R3 4.6 (Windows Server 2003) to SAP ERP 6.0 (Windows Server 2008 R2). Part of the migration will of course be to export the data from the R3 system's database (2TB) and import it on the ERP 6.0 system using programs named r3load and r3unload.

From what I've been told this will be performed the following way: On day X we will start the export on the R3 system using r3unload which will dump data from the DB to text files on a SMB/CIFS-shared logical drive which resides on an EVA5000. While the export is running, r3load on the new ERP 6.0 system picks up the text files from the share and imports them to the new DB.

We're not sure where the bottleneck will be, but since the old system is running Windows Server 2003 and based on our experience 2003 SMB/CIFs transfers never fully utilize 1GbE, the bottleneck might be the network.

We are therefore considering to make the EVA 5000 LUN to which the text files are written also available on the new system so all data gets transfered over the SAN only - which should be much faster than using server 2003 SMB/CIFS transfers over 1GbE.

However, as far as I know you cannot map two writable NTFS LUNs to two Windows servers at the same time. Is it therefore possible to map the LUN as read/write to the old system (2003) and at the same time as ready only to the new system (2008 R2)?

When looking at Command View it unfortunately doesn't seem to be possible as the option read only or read/write is LUN and not host based (unlike on the MSA2000 for example...).

Is it true that this is not possible with the EVA? Are there any workarounds for making a NTFS LUN visible to Windows hosts at the same time?

Any other suggestions are appreciated as well!

Thanks

[Jeremy C]

Create a snapshot and present it to the server you want to have the read-only LUN. That's the practice I've used in similar situations.

[Steven Clementi]

The short answer is no. As you experienced, the read / read-write setting is on the vDisk itself, not the presentation of the vdisk.

If you have a Business Copy license, you can do as suggested... or you can make a snapclone.

If you don't have BC, then you might be able to get a 'demo" license from HP for 30 days to do the migration.

If you don't need direct access to the LUN, you could always just do a network share on the source, then map the drive on the destination. Unfortunately, that would be a "network" related copy and would take some time.

Another option would be to present a new disk to the source server, if you have the space.... and either copy over the data or set up a simple OS mirror. Once the disk is normalized and in sync, break the mirror and unpresent the disk from the source... and re-present it to the destination.


Steven

[sam bell]

Thanks for your replies.

From what I have been told the export/import process is nearly realtime, meaning that shortly after a flat file has been exported from the old system it is picked up and imported by the new system. Using a snapshot or unpresenting/presenting a LUN would mean that we cannot start the import before the export has finished.

I've also performed some test with the MSA2000G2 which allows mapping a LUN to one server as read/write and to a second one as ready only. But even though it is possible to map the LUN to two windows servers at the same time it doesn't work as expected: Data that is written to the LUN on host A is not visible on host B until the drive gets reinitialized...which means that writing the data on host A and shortly picking them up on host B doesn't work.

Anyway - we might have luck even with using SMB/CIFS transfers of the network. Since the new server is 2008 R2 based and therefore utilizes the Windows nextgen tcp/ip stack I found that SMB/CIFS transfers nearly fully utilize GbE as long the transfer is started on the 2008 server. I.e. when downloading a file from the 2003 server to the 2008 server I achive about 75-80mb/s. When uploading a file from the 2003 server to the 2008 server I don't get more than 35mb/s.

Since r3load will pick up (download) the data from the 2003 system network speed should not be a problem.