Hi Galery,
You are running a MIXED media enviroment. There are potential problems in this stiuation, specially with processes like space reclaimation, backup stg etc that needs two mount points. Below is a section from TSM admin Guide that describes potential problems in these situations:
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Some restrictions apply when mixing Ultrium Generation 1 |with Ultrium Generation 2 or Generation 3 drives because of the |way in which mount points are allocated. For example, processes that require multiple mount points that include both Ultrium Generation 1 and Ultrium Generation 2 volumes might try to reserve Ultrium Generation 2 drives only, even when one mount can be satisfied by an available Ultrium Generation 1 drive. Processes that behave in this manner include the MOVE DATA and BACKUP STGPOOL commands. These processes will wait until the needed number of mount points can be satisfied with Ultrium Generation 2 drives.
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And here is the complete sections that discusses this:
Defining and Updating LTO Device Classes
The LTO device class supports LTO Ultrium drives and media. When working with the LTO device class, you need to consider the following parameters:
LIBRARY
See Library.
ESTCAPACITY
See Estimated Capacity.
MOUNTRETENTION
See Mount Retention Period.
MOUNTWAIT
See Mount Wait Period.
PREFIX
See Tape Label Prefix.
|WORM
|See WORM.
In addition to the parameters listed above, you also need to consider the FORMAT and MOUNTLIMIT parameters for which there are special considerations when mixing LTO Ultrium media and drives.
Format
|If you are considering mixing different generations of LTO media |and drives, be aware of the following restrictions:
||LTO Generation 1 drives can read and write Generation 1 media only. |LTO Generation 2 drives can read and write both Generation 1 and Generation |2 media. |LTO Generation 3 drives can read and write both Generation 2 and Generation |3 media. However, LTO Generation 3 drives can only read Generation 1 media.
|If you are mixing different types of drives and media, you should |configure different types of device classes: one for each type of media. Use |the FORMAT parameter in each of the device class definitions to specify the |exact media type. (Do not specify FORMAT=DRIVE). For example, if you are mixing |Ultrium Generation 1 and Ultrium Generation 2 drives, specify FORMAT=ULTRIUMC |(or ULTRIUM) for the Ultrium Generation 1 device class, and FORMAT=ULTRIUM2C |(or ULTRIUM2) for the Ultrium Generation 2 device class.
Both device classes can point to the same library in which there can be Ultrium Generation 1 and Ultrium Generation 2 drives. The drives will be shared between the two storage pools. One storage pool will use the first device class and Ultrium Generation 1 media exclusively. The other storage pool will use the second device class and Ultrium Generation 2 media exclusively. Because the two storage pools share a single library, Ultrium Generation 1 media can be mounted on Ultrium Generation 2 drives as they become available during mount point processing.
Note:
| |If you are mixing Ultrium Generation 1 and Ultrium |Generation 3 drives and media in a single library, you must mark the Generation |1 media as read-only and all Generation 1 scratch volumes must be checked |out.
Mount Limit
In a mixed media library, in which multiple device classes point to the same library, compatible drives will be shared between storage pools. Special attention needs to be paid to setting an appropriate value for the MOUNTLIMIT parameter in each of the device classes. For example, in a mixed media library containing Ultrium Generation 1 and Ultrium Generation 2 drives and media, Ultrium Generation 1 media can get mounted in Ultrium Generation 2 drives.
Consider the example of a mixed library that consists of the following:
Four LTO Ultrium Generation 1 drives
LTO Ultrium Generation 1 media
Four LTO Ultrium Generation 2 drives
LTO Generation 2 media
LTO Ultrium Generation 1 device LTO1CLASS specifying FORMAT=ULTRIUMC
LTO Ultrium Generation 2 device LTO2CLASS specifying FORMAT=ULTRIUM2C
LTO Ultrium Generation 1 storage pool LTO1POOL based on device class LTO1CLASS
LTO Ultrium Generation 2 storage pool LTO1POOL based on device class LTO2CLASS
The number of mount points available for use by each storage pool is specified in the device class using the MOUNTLIMIT parameter. The MOUNTLIMIT parameter in the LTO2CLASS device class should be set to 4 to match the number of available drives that can mount only LTO2 media. The MOUNTLIMIT parameter in the LTO1CLASS device class should be set to a value higher (5 or possibly 6) than the number of available drives to adjust for the fact that Ultrium Generation 1 media can be mounted in Ultrium Generation 2 drives. The optimum value for MOUNTLIMIT will depend on workload and storage pool access patterns.
As part of standard operational management, the MOUNTLIMIT setting needs to be monitored and adjusted to suit changing workloads. If the MOUNTLIMIT for LTO1POOL is set too high, mount requests for the LTO2POOL might be delayed or fail because the Ultrium Generation 2 drives have been used to satisfy Ultrium Generation 1 mount requests. In the worst scenario, too much competition for Ultrium Generation 2 drives might cause mounts for Generation 2 media to fail with the following message:
ANR8447E No drives are currently available in the library.
If the MOUNTLIMIT for LTO1POOL is not set high enough, mount requests that could potentially be satisfied LTO Ultrium Generation 2 drives will be delayed.
|Some restrictions apply when mixing Ultrium Generation 1 |with Ultrium Generation 2 or Generation 3 drives because of the |way in which mount points are allocated. For example, processes that require multiple mount points that include both Ultrium Generation 1 and Ultrium Generation 2 volumes might try to reserve Ultrium Generation 2 drives only, even when one mount can be satisfied by an available Ultrium Generation 1 drive. Processes that behave in this manner include the MOVE DATA and BACKUP STGPOOL commands. These processes will wait until the needed number of mount points can be satisfied with Ultrium Generation 2 drives.
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I myself run a mixed media environment with 6 G3, 4 G2 and 1 G1 drive and time to time see the problem that even when mount points are available in G3 drives, processes that are using G2 says no mount point available. Since I have large number of drives this does not become a porblem. In your case the best bet is to have both drives of the same type either LTO2 or LTO3.
You may check with IBM support but I am sure that they will tell you the same thing.
Best Regards
