define paths question

[cheffern]

hi all -

I have two 3584 libraries attached to an AIX 6.1 server running TSM 6.1.2 -
one library with LTO2, and a bigger one with LTO3 tapes.

LTO2 setup is fine - it's what we had been using up until adding the LTO3 lib today.
OS can see everything, cabling all good, etc.
just wondering though how to add the LTO3 -

normally I would say:

define path TSM1 IBM3584_LTO2 srctype=server desttype=library device=/dev/smc0
define path TSM1 IBM3584_LTO3 srctype=server desttype=library device=/dev/smc1

however, I have multi paths for the LTO3 library as follows:

smc1 Available 07-08-02 IBM 3584 Library Medium Changer (FCP)
smc2 Available 07-08-02 IBM 3584 Library Medium Changer (FCP)
smc3 Available 08-08-02 IBM 3584 Library Medium Changer (FCP)
smc4 Available 08-08-02 IBM 3584 Library Medium Changer (FCP)

so I am not sure how to add these, as I can add the first ok -
but how to add the other 3 to get them to work?

libraries are already added (IBM3584_LTO2 & IBM3584_LTO3)...

tia -
-Chef.

 

[ChrisRees]

You should only have one library type path defined in TSM for each library.

What you are seeing are smc devices for multiple control paths defined on your lto3 library. You can see which drives are classed as control path devices from the front panel on the library or under Drives > Control Paths on the web gui.

If you do lsattr -El smc1 you will get to see which tape drive it refers to by the last two digits of the node_name

for example, here smc0 = drive4

lsattr -El smc0 | grep node_name
node_name 0x500507630f113a04 World Wide Node Name False

Are you using control path failover as well?

Hope that helps

 

[nezih]

What is your Atape level? Multipathing controlled by atape driver...
and check this;
http://publib.boulder.ibm.com/infoc...itsm.srv.doc/c_multipath_io_support_unix.html

 

[cheffern]

thank you for the replies.

lsattr -El smc1 | grep node_name gives me:
node_name 0x500507630f0a6161

so does that mean it only is mapped to drive 61?

we have 2 zones, 2 fibers, 40 drives per fiber (to isolate drives to fibers).
so by having 4 /smc paths, we should see more than 1 drive per path.

does that make sense?

as for CPF - not using yet, but trying something now...

-Chef.

 

[ChrisRees]

Exactly what is your library config, number of frames, number of drives inside each frame?

Could you post your zoning config as well.

My initial point stands though: you only need one library type path for each library so the number of smc's doesn't really matter that much. Its only if you library control path drive breaks and you want to change the library path to use a different drive/control path that you need to worry about the other smc devices..

Cheers

 

[nezih]

in the multipathing architecture you must see each drive from both hba's. it's also protects you from the hba failures and there is load balancing on hba's. if you isolate the drives you'll have only Library Path failover.

 

[cheffern]

hi -

thx for that reply.
your path explanation makes perfect sense. thx!

we just made a change so we now see 1 controller instead of 4.
however, in case of a failover we do want 2 -
but I am not understanding exactly how we can have 1 controller anyway if we have 2 zones.?.?.

as for lib cfg - 8 frames, 2 fibers (4 frames each, 40 drives each)
not sure what you need to see for zoning info...?

also - was reading and found this statement:

"Also there is no automatic failover for the 3584."

so does that mean that even if we have 2 controllers, and 1 breaks -
we have to somehow manually move to the 2nd controller?

thx!
-Chef.

 

[cheffern]

What is your Atape level? Multipathing controlled by atape driver...
and check this;
http://publib.boulder.ibm.com/infoc...itsm.srv.doc/c_multipath_io_support_unix.html

Atape.driver 11.7.6.0

 

[nezih]

Then you need to upgrade your firmware because the newer levels of firmware supports Automatic Control Path Failover

http://www-03.ibm.com/systems/storage/tape/ts3500/features.html

 

[ChrisRees]

So is each tape drive zoned to two HBA's? (40 drives in total)

Are you going to use CPF and DPF ?

 

[cheffern]

thx!

Then you need to upgrade your firmware because the newer levels of firmware supports Automatic Control Path Failover

http://www-03.ibm.com/systems/storage/tape/ts3500/features.html

is the TS3500 the same as 3584?

 

[ChrisRees]

thx!



is the TS3500 the same as 3584?

Yes its the same...

 

[cheffern]

So is each tape drive zoned to two HBA's? (40 drives in total)

Are you going to use CPF and DPF ?

no - actually one per each.
re: CPF and DPF - now you are way above my head
I'm new to this zoning stuff!

I think what we are going to do - based on posts here -
upgrade the Atape firmware for one...
then setup 2 controller paths for this monster lib -
use 1 and leave the other for failover in case we need it.

sounds like the simplest path to take to me.
what do you think?
or are there advantages to setting this up another way?
and will it work if we have 2 zones setup like this?

thx for your input!
-Chef.

 

[ChrisRees]

DPF - datapath failover
CPF - control path failover

These are explained in the AIX Device Driver installation guide. These are extra features that you have to pay for, so I'm guessing you havn't got it. Essentially they make the drives and library more resilient to fibre cable/ fibre adapter failure. Maybe you should look into buying these features..

In your configuration set one drive on one HBA as a required control path on the library, set one drive on the other HBA as a enabled control path.

You should then see two smc devices. Point you TSM library path at one of those. If that drive ever fails or AIX loses its san connection to it, you'll see the library stop working completly. Then you'll have to update the path to use the other smc device.

But another question that springs to mind... you have 80 tape drives and you expect to run all those through 2 fibre ports..??

You'll get terrible performance .. what speed fibre adapters are they??

These things are always much easier to explain/understand face to face !!

 

[Mikey D]

In your configuration set one drive on one HBA as a required control path on the library, set one drive on the other HBA as a enabled control path.

You should then see two smc devices. Point you TSM library path at one of those. If that drive ever fails or AIX loses its san connection to it, you'll see the library stop working completly. Then you'll have to update the path to use the other smc device.

If they have CPF licensed on the library then the real way to do this so you don't have to update paths in TSM is to set alternate paths in AIX in the atape driver

example:
chdev -l smc0 -aalt_pathing=yes
chdev -l smc1 -aalt_pathing=yes

etc...

 

[ChrisRees]

Yes but they don't have CPF..

cheffern: can you take a look in the back of your library. If you bought CPF/DPF you'll find some stickers on the inside of the library , frame 1, with the license keys on..

 

[Mikey D]

Yes but they don't have CPF..

cheffern: can you take a look in the back of your library. If you bought CPF/DPF you'll find some stickers on the inside of the library , frame 1, with the license keys on..

Ah thought I had ready he had CPF at least, yeah then your method would be the best way with some SANdiscovery maybe.

I wish we could enter those CPF keys and capacity keys via the Web management

 

[cheffern]

But another question that springs to mind... you have 80 tape drives and you expect to run all those through 2 fibre ports..??

You'll get terrible performance .. what speed fibre adapters are they??

C5 fibers. 2gbps. still don't think that will float?
for us to add more fiber cards we would need to add an I/O drawer to the current server
so we have what we have (for now)

also - we do have the CPF keys! yippee!
will get to that later...

 

[ChrisRees]

I'm not familiar with a C5 fibre? Whats that?

Ok if you have CPF that changes things !!

Zone two tape drives to be able to see both fibre cards. This will give you 4 smc devices.

register your cpf key (/usr/lpp/Atape/dpfkeys -a "key")

then run

/usr/lpp/Atape/instAtape -a to create the alternate paths.

This should mean you end up with PRI and ALT smc devices if you do
lsdev -C | grep smc


smc0 Available 03-09-02-PRI IBM 3584 Library Medium Changer (FCP)
smc1 Available 06-09-02-ALT IBM 3584 Library Medium Changer (FCP)
smc2 Available 02-08-02-ALT IBM 3584 Library Medium Changer (FCP)
smc3 Available 02-09-02-ALT IBM 3584 Library Medium Changer (FCP)


Then point your TSM library path at the smc device which is PRI.

Phew !

 

[ChrisRees]

To give you an idea, I wouldn't normally put more than 4 LTO3 drives on a single HBA port...even 4 is probably one too many.. thats one a 2Gb SAN fabric.

thats another question.. how many SAN switches are you using? Are all these drives sitting in One fabric?