Date: Sun, 26 Jul 1998 14:27:19 -0700 From: Mike Smith <mike@smith.net.au> To: Karl Denninger <karl@mcs.net> Cc: Mike Smith <mike@smith.net.au>, Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, Dan Swartzendruber <dswartz@druber.com>, current@FreeBSD.ORG Subject: Re: MMAP problems Message-ID: <199807262127.OAA11981@antipodes.cdrom.com> In-Reply-To: Your message of "Sun, 26 Jul 1998 13:46:52 CDT." <19980726134652.16525@mcs.net>
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> On Sun, Jul 26, 1998 at 09:47:54AM -0700, Mike Smith wrote: > > > And I can confirm that the trash IS being written to disk; its definitely > > > there on stable storage when you go look for it later. > > > > > > The data which gets written is usually a block of zeros, but it may not be; > > > it can also be random trash. Its also not always one block (it could be > > > more than one), but it IS always, at least from what I'm seeing here, a > > > multiple of 512 bytes (disk blocksize). > > > > The significant question in light of Garrett's description seem to be > > whether the trash that's written is actually being written by the > > process in error because that's what it got from a previous read, or > > whether the process is actually writing the right stuff and it's being > > corrupted on the way down. > > Its relavent data (its not COMPLETE junk; rather, its pieces of another > article), so I would say its probably being written in error from a previous > read. It would, naturally, be useful to verify this. Can you instrument your application to check the data as they're read? -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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