Tape Library Connection to TSM Server/ Direct Attached or via FC Switch?

bullfighter000

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PREDATAR Control23

I want to upgrade my FC LTO4 Tape Library to an LTO6 . Currently, the LTO4 is connected to the TSM server, using FC Switch. To save on a cost of a FC Switch, I wanted to know if I can direct connect the new Tape Library to the TSM server. How many HBAs would I need on the TSM server, if I want to connect the LTO6 TL with 4 LTO 6 drives. ( One from each drive and the library, so 5 ? )
 
PREDATAR Control23

For direct attach, you don't have a choice except a one-to-one relationship. The robotics normally rides with one tape drive unless you have this configured to be controlled separately.

In your case of 4 LTO drives(assuming that the robotics is riding one one drive), you need 4 ports on the Fiber HBA, or 5 if the robotics is separated,

Here is the caveat: if you expand the system for more tape drives, you have to add more Fiber HBA connections and probably shutdown the physical server to add new Fiber HBAs. If you have a Fiber switch, you don't have to shutdown the system to add the new tape drive. For this reason, I would not consider direct attached tape libraries. Too much admin hassle.
 
PREDATAR Control23

So just making sure I get your point, a direct attached architecture works well if the number of drives are low as each drive will need its own dedicated HBA on the TSM server to be connected to.
And If I have a Fiber Switch in place, then I can simply added extra drive to the TL and connect them to the empty ports on the switch without adding any extra HBAs to the TSM server as they would share the connection. Does the Library then automatically handle which drive share the connection to the TSM server ? And also, do I have to worry about any zoning on the Switch.
 
PREDATAR Control23

So just making sure I get your point, a direct attached architecture works well if the number of drives are low as each drive will need its own dedicated HBA on the TSM server to be connected to.
And If I have a Fiber Switch in place, then I can simply added extra drive to the TL and connect them to the empty ports on the switch without adding any extra HBAs to the TSM server as they would share the connection. Does the Library then automatically handle which drive share the connection to the TSM server ? And also, do I have to worry about any zoning on the Switch.

Any new device needs to be re-scanned into the OS so Windows can see it.

If you had configured your TSM server correctly like: 4 fiber connections to the switch, you can safely handle 8 LTO 6 drives with the robotics riding on one tape drive. This way, you don't have to add Fiber HBAs when you add a new tape drive

Of course, you have to zone properly the server and tape drives on the Fiber switch to get things going. Likewise, zoning is needed when you add tape drives into the switch.

How would the TSM server know that there is a new tape drive without the tape drive zoned properly?

In the case of a direct attach, the limit of how many drives you can attach is the number of PCI bus you have available for use. There are cases wherein Fiber HBAs don't work unless the PCI is a Master bus. Servers rarely have more than 2 or 3 Master bus so this limits the Fiber HBA you can have.
 
PREDATAR Control23

Have just moved from direct attached to switch attached at our site. With an upgrade of our TSM server, the new HBA's did not support direct attached tape. We now have the opportunity to configure LAN free backups. This may be an advantage useful to you.
 
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