From: Matthew Wilcox <matthew@wil.cx>
To: Artem Bityutskiy <dedekind@yandex.ru>
Cc: David Woodhouse <dwmw2@infradead.org>,
Chris Worley <worleys@gmail.com>,
linux-fsdevel@vger.kernel.org
Subject: Re: What's the "prepare_discard_fn" supposed to do?
Date: Fri, 10 Oct 2008 06:58:53 -0600 [thread overview]
Message-ID: <20081010125853.GE25780@parisc-linux.org> (raw)
In-Reply-To: <48E5C047.7020004@yandex.ru>
On Fri, Oct 03, 2008 at 09:48:39AM +0300, Artem Bityutskiy wrote:
> Sorry for my ignorance, but why "discard" is used in hard drive? What
> may it improve? I've always been thinking it is only useful for SSD and
> other FTL-enabled beasts.
If you look at the work being done in T10, it's also envisaged as being
useful for large storage arrays where you do "thin provisioning" --
eg pretend that twenty clients each have a terabyte of disc and only
buy five terabytes of disc for the array. When they start to use four
terabytes, you'll buy some more discs for it, and nobody will ever know.
In order to make this work well, you have to know when files really have
been deleted.
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
prev parent reply other threads:[~2008-10-10 12:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-02 13:45 What's the "prepare_discard_fn" supposed to do? Chris Worley
2008-10-02 13:52 ` David Woodhouse
2008-10-03 6:48 ` Artem Bityutskiy
2008-10-03 6:53 ` David Woodhouse
2008-10-10 12:58 ` Matthew Wilcox [this message]
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