[TUHS] The evolution of Unix facilities and architecture

Noel Chiappa jnc at mercury.lcs.mit.edu
Sat May 13 01:12:56 AEST 2017


    > From: "Ron Natalie"

    > Ordered writes go back to the original BSD fast file system, no?  I seem
    > to recall that when we switched from our V6/V7 disks, the filesystem got
    > a lot more stable in crashes.

I had a vague memory of reading about that, so I looked in the canonical FFS
paper (McKusick et al, "A Fast File System for UNIX" [1984)]) but found no
mention of it.

I did find a paper about 'fsck' (McKusick, Kowalski, "Fsck: The UNIX File
System Check Program") which talks (in Section 2.5. "Updates to the file
system") about how "problem[s] with asynchronous inode updates can be avoided
by doing all inode deallocations synchronously", but it's not clear if they're
talking about something that was actually done, or just saying
(hypothetically) that that's how one would fix it.

Is is possible that the changes to the file system (e.g. the way free blocks
were kept) made it more crash-proof?

     Noel



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