First of all, I am a manufacturer of a Virtual Tape Appliance that emulates 3480, 3490 and 3590 tapes, z/Appliance. We, like most VTAs that are not IBM's, operate as a MTL ( manual tape library ), and we support auto mounting via the LDD CCW ( Load Display ). For z/OS, that is the message like MABC001S that real devices displayed. The M for mount, the S for SL label and then ABC001 for the volume serial number. PRIVAT or SCRTCH for the vol ser indicate that the appliance should pull from the scratch list it is maintaining.
Second, as part of the communication process, the LPAR number is sent. This information along with the various CCWs that affect ASSIGNMENT, is how we manage and communicate with the LPAR OS as to the availability of a DRIVE. We support up to 254 LPARs, although that is beyond what IBM presently supports. Now, you can VARY the device to be AUTOSWITCHed. That and configuring via the IO/GEN multiple LPARs availability enables the use of a drive for several LPARs. V 580,AS,ON This is fine when you are operating a SYSPLEX, because a SYSPLEX typically shares the tape pool/vault. If that is not the case, then configure the VTA with multiple control units or devices and limit the scope of the control unit or device to specific LPARs. For example, with our z/Appliance you can configure a single control unit with 16 devices and each could be assigned a unique LPAR number and tape pool. Or configure 16 Controllers with 4 devices each with each controller assigned to a unique LPAR and yet they could all share the same pool if you wanted to do that. The AUTOSWITCH configuration makes sense with expensive real devices. However, with Virtual Tapes, we license by the number of active tape mounts, not the number of devices defined. This avoids all the hand shaking that has to be done by the OS to locate a free tape device. A process that adds latency to tape drives in use. If you have 4 LPARs and the maximum number of drives you would ever use is 8, then define 4 control units with eight devices each and purchase a license for 8 devices. So even though you have 32 devices defined in the IOGEN, the license would defer mounts greater than 8 in this case. For additional information, please visit our website at https://www.atsmigrations.com . Leave a contact and i would be happy to discuss the process with you. Thanks Paul ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
