Where can I find a list of HP DLT libraries and what version of MPE can drive them?
No libraries are supported on MPE in random mode. While autoloaders can easily be made to work quite well on the HP 3000, one requires specialized software in order to make use of the full functionality of a DLT library. What is important from an HP 3000 point of view is as follows:
• The tape drives in the library must be supported on MPE and can be connected to the 3000. This means the drives must be DDS or DLT4000, DLT7000 and DLT8000. If the system is an HSC (pre-PCI) architecture, the drives must be HVD SCSI. If the system is a PCI system (A- or N-Class,) the drives can also be LVD.
• The connection to the library robot or picker, must also be supported on the 3000, again HSC needs HVD and PCI can do LVD or HVD.
• Finally you must have software that will connect to the picker and drive it. This software can either be running on MPE or on another system, to which the picker is connected. MPE itself cannot drive a robotic library.
I want to install disc drives larger than HP's 144GB. What issues should I consider?
The maximum disk size for MPE/IX is theoretically 2^31 sectors. Due to overhead and rounding DISCFREE output will show 2,147,483,632 sectors for such a disk, this is equal to 549,755,809,792 bytes. So, a disk of this size would likely be sold as a 550 GB disk (powers of ten) though it contains 512 GB from an engineering perspective (powers of two).
Even with the Large Disk Patches, MPE/iX users should be cautious when considering the usage of disks larger than 18-36 GB on MPE/iX systems for the following reasons:
MPE/iX transaction throughput increases when MPE is allowed to spread IO across disks. Even though newer disks are faster than older disks there are limits to disk speed and bus speed which must be taken into account.
Moving from nine 2 GB disks to one 18 GB disk, for example, will often create a disk IO bottle neck. For best performance we recommend that the number of MPE LDEVs never be reduced - if one has nine 2 GB disks then they should be replaced with nine 18 GB disks to ensure no loss of throughput.