Date: Tue, 13 May 2008 05:14:52 -0700 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Anthony Pankov <ap00@mail.ru> Cc: freebsd-hackers@freebsd.org Subject: Re: BDB corrupt Message-ID: <20080513121452.GA70860@eos.sc1.parodius.com> In-Reply-To: <2117635718.20080513154406@mail.ru> References: <op.uavxx8ip2n4ijf@duckjen.nextgentel.no> <9FC19AC2-DAD8-418C-8B9C-F129DEC58CEF@gmail.com> <15336578.20080512123806@mail.ru> <200805121153.00809.jonathan%2Bfreebsd-hackers@hst.org.za> <1663320218.20080512223531@mail.ru> <20080512152430.3720683e@mbook.local> <2117635718.20080513154406@mail.ru>
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On Tue, May 13, 2008 at 03:44:06PM +0400, Anthony Pankov wrote:
> If concurrency is the only problem then:
> 1. ?an data corruption be avoided? Or this is impossible?
> 2. How?
Use Sleepycat/Oracle DB instead? The libc DB1.x, despite being
"mature", really should be deprecated in some manner.
I'm sure there are others I've forgotten, but the only thing I can think
of in the base system which relies on DB1.x is sendmail (which IMHO
should really be removed from the base system and replaced with a small
standalone mailer -- but that's been discussed in a previous thread in
the past). Even "simple" ports like postgrey pull in db41, even though
they could technically "work fine" with DB1.x.
> If all BDB readers would use O_SHLOCK and all writers O_EXLOCK is it
> guarantee for data integrity?
The corruption I've seen in the past results in DB operations failing
for no particular reason ("what do you mean those are all the records?
No! I just inserted a bunch more!"). It turns out some of the data in
the actual .db file is corrupt -- even when locking is used everywhere.
It's as if the code has some weird bug where it'll write bogus data to
the file for some reason.
I'll ask you this: is there some particular reason you can't just write
to a file yourself, using your own/documented file format? Why does DB
have to be used?
--
| Jeremy Chadwick jdc at parodius.com |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
| Making life hard for others since 1977. PGP: 4BD6C0CB |
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