[Info-vax] free blocks

[Bob Koehler]

In article <kbeubt$11e$1 at news.albasani.net>, Jan-Erik Soderholm <jan-erik.soderholm at telia.com> writes:
> 
> And, this was/is not done dynamicaly, as far as I know. You had/have to run
> a specific tool to check this (ANALYZE /MEDIA <dev>).

   Nope.  You used anal/media to initialize the bad block file.  Bad
   blocks discovered while the disk was in use were added to the bad
   block file.

   When VMS sees a bad block on write, it marks the block bad and writes
   the data on a different block, and nevre uses that block again
   (unless a tool like anal/media removes the mark).

   When VMS sees a bad block on read, it marks the block bad and does the 
   best it can to read the data.  Each attempt to read will log I/O errors 
   on the device.  Deleting the file which contains the bad block will 
   cause the block not to be used again.  The application reading the 
   file will see I/O errors also, if it looks.

   VMS doesn't need smarts to deal with revectoring disks differently.
   VMS just never sees bad blocks reported from the hardware.