XPost: aus.computers   
   From: me@bugger.off.com.au   
      
   On 28/12/2025 12:43 pm, Lawrence D’Oliveiro wrote:   
   > On Sun, 28 Dec 2025 11:12:22 +1000, keithr0 wrote:   
   >   
   >> ... with any useful sort of RAID implementation, you can hot replace   
   >> the bad drive, without the need to restore from backup.   
   >   
   > That’s where the “high availability” comes in.   
   >   
   >> All the data remains available throughout.   
   >   
   > Until you discover a software bug (or an operator screwup) has deleted   
   > an important database. Which you then need to restore from ... where?   
      
   Of course there were still backups, not always what you think though.   
   The machines that I worked on could take checkpoints online, some users   
   checkpointed on an hourly basis.   
      
   Resilience was an important facto with our customers, another storage   
   server could be connected vie optical fibre, the slave machine being a   
   remote mirror of the the master. After the Twin Towers incident, some   
   customers took it even further. Maybe the master was in New York, the   
   first slave 50Km away in New Jersey, and a second slave connected to the   
   first across the continent in LA or San Francisco. The first slave would   
   be one transaction max behind, the second several, as a last ditch copy.   
   The slaves could also be used as a test load for system changes and   
   resynced afterward.   
      
   >> I spent 20 years working on large storage systems, beginning with   
   >> boxes of 128 5 1/4" 9gig SCSI drives, going on with larger and   
   >> larger drives dropping to 3 1/2" SCSI then Ultra SCSI, fibre the first    
   channel   
   >> and finally SOS (SCSI Over Serial) drives.   
   >   
   > Presumably, judging from your comments, you were more on the hardware   
   > side, not the software side.   
      
   I worked on the hardware side for 30 years then wrote software   
   professionally for another 25. I still write stuff for micro controllers   
   like the ESP32 and the Raspi Pico for fun.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)