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Date: Wed, 19 Aug 2009 21:38:27 -0400
From: Mark Lord <liml@rtr.ca>
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To: Jamie Lokier <jamie@shareable.org>
Cc: Christoph Hellwig <hch@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Paul Mackerras <paulus@samba.org>,
       Linus Torvalds <torvalds@linux-foundation.org>, xfs@oss.sgi.com,
       linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org,
       linux-kernel@vger.kernel.org, jens.axboe@oracle.com
Subject: Re: [PATCH, RFC] xfs: batched discard support
References: <20090816004705.GA7347@infradead.org> <20090819203916.GA25296@elte.hu> <20090820010552.GA22107@infradead.org> <20090820011004.GC14005@shareable.org>
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Jamie Lokier wrote:
..
> I don't remember - does TRIM guarantee the blocks read zeros afterwards?
..

No, it doesn't.

A drive can optionally support "deterministic TRIM", whereby it will return
consistent data for any given trimmed sector afterwards, but that doesn't mean zeros.

-ml