sr16+@andrew.cmu.edu (Seth Benjamin Rothenberg) (09/07/89)
My department will soon be buying a large UNIX box (Vax 5400/5800 or TI 1000 something). TI says the file system is secure - i.e., you could turn the machine off and on again and no files would be lost, and you could log in immediately. We seem to understand from DEC that we would need to run fsck before we could log in, and that this requires 10 minutes per disk. We have 12 drives. We don't have 2 hours to spare. Does anyone have any idea what these people are saying? i.e., did DEC write an implementation that doesn't use checkpointing and flush()? (These would ensure that what's to be done will get done, and what has been done was written to disk) Thanks Seth Rothenberg sr16@andrew.cmu.edu
gwyn@smoke.BRL.MIL (Doug Gwyn) (09/07/89)
In article <AZ1RhMO00Ug7M2=JlU@andrew.cmu.edu> sr16+@andrew.cmu.edu (Seth Benjamin Rothenberg) writes: >My department will soon be buying a large UNIX box (Vax 5400/5800 or TI >1000 something). TI says the file system is secure - i.e., you >could turn the machine off and on again and no files would be lost, >and you could log in immediately. We seem to understand from DEC that >we would need to run fsck before we could log in, and that this requires >10 minutes per disk. We have 12 drives. We don't have 2 hours to spare. Generally one runs fsck on all spindles at the same time, which drastically reduces the wall-clock time for this procedure. Current releases of UNIX System V are supposed to have fully hardened file systems, so that after a power outage any on-disk inconsistencies will not cause problems to spread. (Of course files being modified at the time of outage might be corrupted.) I don't know how true that really is, or whether you could get away with it using a BSD filesystem. >Does anyone have any idea what these people are saying? i.e., did DEC >write an implementation that doesn't use checkpointing and flush()? If you shut the system down cleanly, no fsck is necessary. It's when the power is suddenly removed that the in-core buffers are not flushed to disk, causing possible file system corruption.