There several backup systems to record the data if the VAX
connection has failed or a disk on the VAX has failed. The first
backup system is the use of floppy disks with the PC. Since all
of the data are stored on the PC, the data can be sent directly
from the F: drive to a floppy disk. The PC can read both
5
" and 3
" disks. Table 3 shows the disk
capacity for each system. The data can then be stored on floppy
disk until they can be sent to the VAX.
A second form of backup for the PC is a tape drive. The Colorado Memory Systems tape drive stores data on QIC-80 tapes. The QIC-80 tapes can store 250 megabytes of compressed data. From here several nights worth of data can be transferred to a single tape. This is a stronger system than the disks because the tape can hold 600 ST-6 images. The entire contents of the PC are backed using this system occasionally.
: Storage Capacity For Lynxx and ST-6 Images.
The data are also backed-up on the VAX with an 8mm or 4mm tape. A tape backup should occur once every month. This backup becomes important if the disk fails. A month's worth of data was lost when one of the VAX data disks failed. The disk in question had stored data from a year before the failure date, but they were stored on tape and recovered. The VAX has a routine that allows TAR procedures to run within VMS.
