Probably many others will chime in on this. I have lost RAID 5 arrays with two disk failures within an hour of each other. RAID is nice, but one must allow for failures.
Long ago I was involved with reading archived tapes and transferring the data to CDs. The programs involved were home-written and the project ended up going nowhere. However, we discovered that tapes kept too long started having errors. (At that point, for the CD copy, we just logged the error and accepted the corrupt data; what else could we do?) How long is "too long"?? It was variable, but measured in a few years. The advice then was to minimally read the tapes every year or so to "retension" them. Don't know if this would apply to more modern tape media. (We also discovered that locally "burned" CDs are not expected last forever.) IMHO, the key point for tape backups are (1) off-site storage, (2) multiple PiT recovery, (3) logical error recovery. All this can be done with disk-only environments involving remote copy and lots of disk space, but all that becomes expensive for smaller shops. Bill Ogden ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
