Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ncar!unmvax!pprg.unm.edu!topgun.dspo.gov!lanl!cmcl2!adm!smoke!gwyn From: gwyn@smoke.BRL.MIL (Doug Gwyn) Newsgroups: comp.unix.wizards Subject: Re: file system integrity Message-ID: <10968@smoke.BRL.MIL> Date: 7 Sep 89 05:11:16 GMT References: Reply-To: gwyn@brl.arpa (Doug Gwyn) Organization: Ballistic Research Lab (BRL), APG, MD. Lines: 23 In article 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.