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From: Roman Shaposhnik <rvs@sun.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] 9pfuse and O_APPEND
Date: Fri, 19 Dec 2008 12:10:10 -0800	[thread overview]
Message-ID: <998EB623-CFD3-4E15-BD85-D2111D8A896B@sun.com> (raw)
In-Reply-To: <a549cb998598f17f5cc92ed39aa6b7c3@quanstro.net>

On Dec 19, 2008, at 11:56 AM, erik quanstrom wrote:
>> Two questions:
>>    1. But before I ask this one: I don't deny that per-file append-
>> only
>>     is *extremely* useful. My question is a different one: what is
>>     the danger of N clients accesing the file X in append-only mode
>>     and M clients accesing it in random access mode? Could you,
>>     please, give a concrete scenario?
>
> credit geoff for bringing this up: upas mailboxes.
> suppose you have upas/deliver trying to deliver a message and at
> the same time you have upas/fs trying to rewrite the mailbox.
> (play along for a bit.  ignore L.mbox and the temporary mbox
> tricks.)


It is difficult to answer your question without knowing what rewrite
actually does and how mailboxes are structured. But in an imaginary
world where a mailbox is a list of constant sized blocks (size<iounit)
a bunch of simultaneous appends and rewrites of existing blocks
would work perfectly well.

Thanks,
Roman.



  reply	other threads:[~2008-12-19 20:10 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-18 23:34 Roman Shaposhnik
2008-12-18 23:57 ` Russ Cox
2008-12-19  0:03   ` ron minnich
2008-12-19  3:06     ` Roman Shaposhnik
2008-12-19  3:26       ` ron minnich
2008-12-19  3:59         ` Roman Shaposhnik
2008-12-19 16:44           ` ron minnich
2008-12-19 19:21             ` Anthony Sorace
2008-12-19 19:31               ` erik quanstrom
2008-12-19 19:41               ` ron minnich
2008-12-19 19:59             ` Roman Shaposhnik
2008-12-19 20:06               ` erik quanstrom
2008-12-19 20:18               ` Charles Forsyth
2008-12-21  5:08                 ` Roman V. Shaposhnik
2008-12-19  3:03   ` Roman Shaposhnik
2008-12-19  3:43     ` erik quanstrom
2008-12-19  3:54       ` Roman Shaposhnik
2008-12-19  4:13         ` geoff
2008-12-19  8:23           ` Russ Cox
2008-12-19 19:49             ` Roman Shaposhnik
2008-12-19 19:56               ` erik quanstrom
2008-12-19 20:10                 ` Roman Shaposhnik [this message]
2008-12-19 20:22                   ` erik quanstrom
2008-12-19 20:02               ` ron minnich
2008-12-19 14:21           ` erik quanstrom
2008-12-19 21:00 ` ron minnich
2008-12-19 21:32   ` Charles Forsyth
2008-12-19 21:29     ` ron minnich
2008-12-21  5:05   ` Roman V. Shaposhnik
2008-12-21 14:45     ` erik quanstrom
2008-12-22 10:02       ` roger peppe
2008-12-25  6:04       ` Roman Shaposhnik
2008-12-25  6:33         ` erik quanstrom

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