Date: Wed, 29 Sep 2004 16:42:33 -0400 From: David Schultz <das@FreeBSD.ORG> To: Nehal <nehalmistry@gmx.net> Cc: freebsd-fs@FreeBSD.ORG Subject: Re: data blocks question Message-ID: <20040929204233.GB30629@VARK.MIT.EDU> In-Reply-To: <20040929101403.000027aa@nehal> References: <20040929101403.000027aa@nehal>
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On Wed, Sep 29, 2004, Nehal wrote: > on my ufs2 partition, there is a file that has a size of 65536, > and has 2 direct blocks only. the block size of the fs is 16k and > fragment block size is 2k. > > how can this be possible? wouldn't 2 direct blocks mean that the > maximum size is 2x16k = 32k? or am i not understanding something > correctly? > > i've made a copy of the file, and the new file has 4 direct > blocks. > > it is a binary file, and i can read it fine (ie, cat it). i've > done fsck on the filesystem and it found no problem. Yes, UFS supports sparse files. That is, you can have a file with parts you haven't written to, and the blocks for those parts won't be allocated. The cp utility doesn't know about this, though, so copies will have the ``holes'' filled with zeroes.
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