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Dual Port Tape drive multipathing

ashjosh
Level 4
Partner

Hi team ,

 

Can we use Dual port Tape drive with Solaris 11 SPARC server as Master / Media Server?

 

What are the prerequisites for it & how to configure multipathing for it. ?

 

I cant disable Solaris MPIO as Storage LUNS are visible on server through it.

1 ACCEPTED SOLUTION

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mph999
Level 6
Employee Accredited
Any OS multipathing must be disabled, NBU will not work properly with it enable, it is unsupported and there is no way around this that I am aware of. Regarding multipathing of tape drives within NBU, currently it has an issue. NetBackup does not provide automatic SAN path failover for tape drives connected through multiple paths http://www.symantec.com/docs/TECH215781

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14 REPLIES 14

mph999
Level 6
Employee Accredited
Any OS multipathing must be disabled, NBU will not work properly with it enable, it is unsupported and there is no way around this that I am aware of. Regarding multipathing of tape drives within NBU, currently it has an issue. NetBackup does not provide automatic SAN path failover for tape drives connected through multiple paths http://www.symantec.com/docs/TECH215781

ashjosh
Level 4
Partner

Hi mph999 ,

 

If i disable multipathing on OS , my OS luns would be a problem.

 

My IT team wants to use both paths of Tape drive to ensure redundancy.

 

How to achieve this. I am confused.

ashjosh
Level 4
Partner

As far as i know Solaris MPIO is only for disks.

 

There is no way i can use Tape multipathing with MPIO.

 

For MPIO  i has to be dependent on netbackup only..

mph999
Level 6
Employee Accredited
This post shows MPIO causes issues with NBU https://www-secure.symantec.com/connect/forums/netbackup-media-server-solaris There are many similar posts, with similar errors. You may be able to disable it per port or per HBA, which would get rid of the MPIO issue. Regarding the TN, there is no workaround, and no current plans to address the issue.

RiaanBadenhorst
Moderator
Moderator
Partner    VIP    Accredited Certified

What NetBackup sees is ultimately controlled by the sg driver. If you manipulate what is in the sg.links and sg.conf you can make it see what you want it to see.

 

You agree Martin?

ashjosh
Level 4
Partner

i believe its not recommended to use tape drive multipathing in Netbackup.

 

It will cause a lot of issues.

mph999
Level 6
Employee Accredited
On Solaris yes, though you have two choices, it works, or it doesn't. You can't get around the fact that NBU does not work with OS multipathing. I had exactly this issue the other week on a call - OS multipathing was breaking NBU.

Michael_G_Ander
Level 6
Certified

Think it can be done through robtest so that NetBackup handles the failover to the alternate path.

http://www.symantec.com/docs/TECH73944  describes the procedure for mutliple robotic paths

The procedure might cover multiple paths for the tape drives too

The standard questions: Have you checked: 1) What has changed. 2) The manual 3) If there are any tech notes or VOX posts regarding the issue

mph999
Level 6
Employee Accredited

The robtest 'thing' is for multi path to the robot only.

ashjosh
Level 4
Partner

I have problem here also.

 

I am using SL150 Tape drive & it has only Drive paths to connect.

NO Robot paths.

 

I think it will go from Drive 1 or Drive 2  in bridged mode.

 

So incase robot is going from Drive-1 , & its down how come robot will be available?

Marianne
Moderator
Moderator
Partner    VIP    Accredited Certified

You need to find out from your hardware installation team (or hardware documentation) how exactly the robotic interface is connected.

If internally 'daisy chained', they will probably be presented to the OS as one target with 2 luns (lun 0 and 1).

If anything happens to the swith port, cable, etc, you will need to fix the problem ASAP.
Drive failure should not affect the robot.

jim_dalton
Level 6

A quick search reveals Marianne is correct:

Both data and commands are sent to the Serial Attached SCSI (SAS) or Fibre Channel data interface on a designated Linear Tape Open (LTO) bridged drive. The bridged drive then handles all communications for the library or library partition. Command and control signals are sent to LUN1 (Logical Unit Number 1) of the bridged drive, which is configured as a SCSI medium changer device. The SCSI medium changer communicates with the SL150library controller across the Automation Device Interface (ADI) on the bridged drive. Data are sent to the remaining LUN on the bridged drive or to LUNs on the other, unbridged drives in the partition, all of which are configured as SCSI sequential-access (tape) devices. A default bridged drive is automatically assigned during library and partition configuration.

 

So the important word here is:  designated. I take to mean you can pick any drive you like but you will get a default.. This is what will need addressing should you lose the designated drive. Though the degree of loss may vary from loss of that drive but robotics continue fine to total loss of everything, as also mentioned by MvdB. Jim

ashjosh
Level 4
Partner

So in Nutshell ,

 

1. Multipathing should be disabled for dual port tape drives

2.Netbackup doesnt support Automatic path failover for multipath drives.

3. In case of bridged Tape library , Switch , port or cable to bridged tape drive is single point of failure & there is no way we can make this redundant.

I think i am stuck & fully redundant solution cant be impllemented.

mph999
Level 6
Employee Accredited
Unfortunately, at least at the moment I believe you are correct, yes.