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MSA 2312fc with two hosts: Question about volume access

 
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Collector

MSA 2312fc with two hosts: Question about volume access

Good day. I recently "inherited" a two-host MSA2312fc configuration from the previous sys admin. This is how everything is configured:

 

Host 1: Windows Server 2003, SP2, connected to MSA via FC port A1 in controller A.

Host 2: Windows Server 2008 x86, connected to MSA via FC port B1 in controller B.

 

Right now, those are the only connections.

 

The SAN consists of two vdisks; one with three volumes, the other with one. All volumes are mapped to all ports. the LUNs are configured as follows:

 

VDISK 1

Vol1 - LUN 0 Default to Host 1, explicit to Host 2

Vol2 - LUN 1 Default to Host 1, explicit to Host 2

Vol3 - LUN 5 On Host 1, LUN 3 on Host 2, both explicit maps

 

VDISK 2

Vol1 - LUN 2 On Host 1, LUN 4 on Host 2, both explicit maps

 

My questions are:

Is this configuration normal? I'm mystified by the LUN assignments. Shouldn't they be the same for all volumes, or does the use of the second controller prevent that?

 

Shouldn't both hosts see the same files presented when they're viewing the same volume? Host 1 shows twelve directories (which it should); Host 2 only shows two. Directories created/deleted on one host do not appear/disappear on the other.

 

Thanks in advance. This is my first time dealing with a SAN with more than one host.

5 REPLIES 5
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Acclaimed Contributor

Re: MSA 2312fc with two hosts: Question about volume access

>> Is this configuration normal?

 

No.

 

You only have this array and 2 servers without any switch, right?

 

So you should connect at least both controllers to each array controller. During presentation you should also present each volume with the same LUN# to prevent to much confusion. The presentation shpuld be set to none as default, then explicit present each volume to the host.

 

Read the CLI admin guide of the array, probably the best to learn how to do this.


Hope this helps!
Regards
Torsten.

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Honored Contributor

Re: MSA 2312fc with two hosts: Question about volume access

I think Torsten meant you should connect both servers to each array controller?

 

>> Shouldn't both hosts see the same files presented when they're viewing the same volume? Host 1 shows twelve directories (which it should); Host 2 only shows two. Directories created/deleted on one host do not appear/disappear on the other.

 

This depends on which file system you have on the disk that's presented to the servers. You need to have a clustered file system that supports access from two hosts simultaneously (NTFS does not).

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Acclaimed Contributor

Re: MSA 2312fc with two hosts: Question about volume access

There is IMHO a serious problem with the default settings of such arrays.

One of the defaults is to present a volume (LUN) to all hosts.

This is in most cases NOT what you want.

So IMHO it is better to set the default to present a volume to none of the hosts and use explicit mapping instead.

I assume you have 2 FC ports per server, so you should connect each port of a server to one array controller, otherwise you don't have any redundancy.


Hope this helps!
Regards
Torsten.

__________________________________________________
There are only 10 types of people in the world -
those who understand binary, and those who don't.

__________________________________________________
No support by private messages. Please ask the forum!

If you feel this was helpful please click the KUDOS! thumb below!   
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Collector

Re: MSA 2312fc with two hosts: Question about volume access

Thanks! The servers are not clustered. One is an ancient domain controller and the other is a newer one. It's not critical that they be clustered. I just wasn't sure whether what I was seeing was normal.

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Collector

Re: MSA 2312fc with two hosts: Question about volume access

Understood. The older of the two machines only has one FC port, but my plan is to wind that down, anyway, and replace it with a newer box that has enough ports for failover.