|
HP OpenVMS Systemsask the wizard |
|
The Question is: Question relates to writing information to disk in a high volume, high reliability scheme. Is it possible to set up shadowing with the following? 1. 4MBlock DECram (8 Ram Disks, 500000 blocks each) 2. a partition on a 9 gb hard disk (HSD10 or HSD30 array) 3. a partition on a 9 gb hard disk HSDxx controllers would be connected to two DSSI channels from separate KFMSA cards in a fail-over mode, Ram Disk would provide for extremely high output rate, shadowed drives would provide reliability. I am afraid this question will stimulate even more questions - maybe we could correspond via email... Jim The Answer is : A requirement for high-performance I/O, the use of the DSSI bus (roughly equivilent to SCSI-1 in performance), the use of OpenVMS VAX V6.2, and the use of an unspecified-model XMI-based VAX system makes for a rather interesting configuration, and would not comprise a configuration that the OpenVMS Wizard would initially consider for the stated task. You can shadow dissimilar devices, assuming the total numbers of blocks match and assuming you have current OpenVMS versions and current shadowing ECOs installed. Shadowing will not assist your performance goals here, as shadowing will require writing to all three spindles involved in the shadowset, and you have a DSSI bus in the way. Shadowing can potentially assist with read performance, and particularly if you have a fast storage device available in the shadowset. Shadowing will not assist with write performance, and particularly not if you have a slow storage device configured into the shadoset. Most any AlphaStation or small AlphaServer system configuration will greatly exceed the I/O performance of this VAX and DSSI configuration, as it will permit the use of Fibre Channel and/or UltraSCSI or faster storage. The OpenVMS Wizard is not in a position to provide consulting services, nor to provide email services.
|