Full Disclosure mailing list archives
Re: Reality, humor, and history (was Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER
From: Dave Horsfall <dave () horsfall org>
Date: Thu, 13 Jan 2005 21:34:55 +1100 (EST)
On Wed, 12 Jan 2005 Valdis.Kletnieks () vt edu wrote:
(*) My all-time favorite "Close, but no ceee-gar" was the advice column for a Unix journal where the author *remembered* the old "3 syncs before halt" adage - but got it Very Wrong by advising "sync;sync;sync;halt". Bonus points if you can remember (a) the *original* reason for the advice *and* (b) how this version was Very Wrong (there's *multiple* answers for this one ;)
Early Unixes -- especially those with slow disks such as the RK05 -- could take several seconds to flush the buffered data to disk. The sync() call only *scheduled* the flush and returned right away, thus the disk data (especially the meta-data such as inodes etc) may not be up to date when you hit the switch (early Unixes did not have a halt command). By typing: # sync # sync # sync i.e. by waiting for the command to return, thrice, you were reasonably sure that the buffers were flushed, especially if you could see the disk activity lamps (not LEDs in those days). By using "sync; sync; sync" the operator did not have to wait, and so was lulled into a false sense of security. This was really important in those days, because the filesystem simply was not as resilient as it is now; a power failure *guaranteed* that you would lose files, and it was time for "check" (in Edition 5, and which became ncheck/dcheck/icheck and eventually fsck) and "clri". -- Dave, who had creamed several PDP-11 Unixes in his time _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
Current thread:
- MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Team Pwnge (Jan 11)
- Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER vh (Jan 11)
- Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Andrew Farmer (Jan 11)
- RE: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Paul Kurczaba (Jan 11)
- Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Kevin Reiter (Jan 11)
- Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Micheal Espinola Jr (Jan 11)
- Reality, humor, and history (was Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Valdis . Kletnieks (Jan 12)
- Re: Reality, humor, and history (was Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Stormwalker (Jan 12)
- Re: Reality, humor, and history (was Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Andrew Farmer (Jan 12)
- Re: Reality, humor, and history (was Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Dave Horsfall (Jan 13)
- Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Robert Hogan (Jan 12)
- Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Kevin Reiter (Jan 11)
- Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Martin Allert (Jan 11)
- RE: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER ALD, Aditya, Aditya Lalit Deshmukh (Jan 12)
- RE: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Paul Kurczaba (Jan 12)
- RE: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER ALD, Aditya, Aditya Lalit Deshmukh (Jan 12)
- <Possible follow-ups>
- Re: MORE CRITICAL FLAWS IN MS WINDOWS EXPLORER Kevin Reiter (Jan 11)