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2012i Sharing data between servers

DavidCleaver11
Occasional Advisor

2012i Sharing data between servers

Hi, I think I'm just missing something, but I don't know what. I have to 7TB volumes in a 2012i and a MSA 2000. I have 4 2003 HP Servers with two nics each, one for the ethernet network, the other used for the iscsi network connected to the same switch as the 2012i. On the 2003 servers I have installed the iSCSI initiator as per the HP document, and up pop my two drives D and E. great, all working. Do the same on the next server, and up they pop again, but write or create a folder on server A I would expect it to show on server B, but it doesnt??? I have allowed rw access in the SMU to the volume I created but not 100% what lun to type so I have used the same for both servers. the problem continues with additional server I add. I also get access denied on some folder and I just can't work out why. Hopefully very simple to resolve, but not by me.

Any help would be great. At the end of the day, I need 4 2003 servers to share data on the volumes I have created on the MSAs.

Many thanks
11 REPLIES
Andy_Stor
Valued Contributor

Re: 2012i Sharing data between servers

Hi David,

If I understood your query correctly, you are trying to map the same LUN to all the four host for read/write access??

As per the storage concept only one initiator can speak to a target at any given time. So if you are trying to give read/write access to all the 4 host at the same time and trying to map it on all the hosts then I would say its something which needs to checked.

Andy.
TTr
Honored Contributor

Re: 2012i Sharing data between servers

It is more that what Andy mentioned. It is also the concept of file ownership, sharing and locking at the server level. Without this kind of control in place, it would be chaos in the filesystems. This kind of control exists only is a server cluster environment or a cluster filesystem setup which does not look like you have in place.
DavidCleaver11
Occasional Advisor

Re: 2012i Sharing data between servers

OK, thank you both, and I think I may have mislead you. I need all 4 hosts to see the data area but the data won't be read by all 4 hosts, it's more of a failover. If I create a folder in my volume called test from server A, I would expect to see that from server B, and if I need to, I should be able to use that data, as long as server A has stopped writing the data. I guess what I'm saying is that the drive that apears in all 4 servers I want to cat as a shared folder does for client PCs. Is this not possible?

Many thanks so far!

TTr
Honored Contributor

Re: 2012i Sharing data between servers

> I need all 4 hosts to see the data area but the data won't be read by all 4 hosts

From the array side it is possible to do that, ie. assign a volume to all 4 hosts. But on each host you need to ensure that the volume is in use by the primary server in r/w mode and just visible by the other servers. If your primary server crashes then you need to change the volume on the OS side to be the r/w volume for the new primary server. You need to verify that in your OS.

If you OS does not provide a safe way to have the volume available for a failover, you do not need to make the volume available to all 4 servers up front. You make the volume available to one server and if that server crashes, you can assign it to another server instantly on the array side.

On another note what kind of data resides on such a volume? If it is "open" data such as a database, you have to go through a recovery process within the database as well. There could inconsistencies on some simple files with other applications as well.
DavidCleaver11
Occasional Advisor

Re: 2012i Sharing data between servers

Hi

The data is just backup data.
So this is what I have done so far:
On server A I see my MSA as Drive D. i created a folder called backup, and then copied a few test accounts into the folder.

On Server B I also had the D drive (same Volume), but no folders can be seen that I created on Server A.

But's heres my biggest concern. I have copied from an old server data to Server A d:\backup. All OK, but now the first folder can't be opened and says "the file or directory is corrupted and unreadable" there is over 3GB of data in this folder and all other folder in d:\backup are still there and readable. Could I have caused this problem when I created a folder from server B in d:\??

I wish I knew what I was doing :(

Many thanks
Víctor Cespón
Honored Contributor

Re: 2012i Sharing data between servers

A explained above, you cannot connect the same drive to two servers with two independent operating systems. Each operating system will think the drive is used only by it and will keep his own file tables and pointers. That's why the files copied on one OS cannot be seen by the other if both are online.
It is different if you copy files, shutdown the OS, then connect the drive to another server. It will have exclusive access to the drive and see files OK.
To share a drive among several servers you need a clustering filesystem, that all servers are ina cluster and the drive is marked as a cluster resource. Then the cluster service manages the access.
DavidCleaver11
Occasional Advisor

Re: 2012i Sharing data between servers

Oh.
Can you recomend a way that I can share the 14TB I have on the MSA2012 and the second MSA2000 between a number of servers. The way I can work it is for each server to use a volume each, so instead of having 2 x 7TB volumes, I can break this down so that each server can use 3.5TB each to store it's data. Is this possible and if so any pointers most welcome :)

Thank you all so far for your help!
Andy_Stor
Valued Contributor

Re: 2012i Sharing data between servers

Hi David,

What I can suggest you in this case is setting up a cluster would be a good option. You can create the volumes on the MSA`s and present it to the SRVA, now you want them to be readable from SRVB to map it over from you network and access the data. Now for the failover Create SRV A as you primary cluster node and create all the resources on the SRVA and make the SRVB as a passive node, now when we have a failure of SRVA, all the volumes will be failed over to SRVB and you achieve redundancy.

I hope it helps.... :-)

Andy
DavidCleaver11
Occasional Advisor

Re: 2012i Sharing data between servers

Thank you, but do I need Advance server for this. the server is 2003 x64.

Is ther no way I can create 4 volumes, allow Srv1 rw access to V1 and deny all others, then Srv2 access to volume2 and deny all overs etc etc

Could this work and give each server 3.5TB of total storage to use?

Thanks again!
Andy_Stor
Valued Contributor

Re: 2012i Sharing data between servers

Yes we need Advance server to setup cluster over it.

We can definately map one volume per server and restrict others to access the volumes.

I mean create Volume1 and then map it as rw to Host1. Remove access for all other host.

Create Volume2 and then map it as rw to host2. Remove access for all other host.. and so on....

Andy
DavidCleaver11
Occasional Advisor

Re: 2012i Sharing data between servers

Again, Thank you Andy!

I would like to go the cluster route, but I just can't go back to my boss and state I need 2 x Advance servers ;-) I will set up the volumes and give access to just one server then deny all others, If that server fails, I guess I just have to change the access rights. Just one last thing if you don't mind, I'm seeing a few other folders deep into the file structure that I can't gain access to, or in fact do anything with. Any ideas what I can do with these, ie how to get over the problem it looks like I have caused?

Many thanks

Dave