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Date: Tue, 6 Oct 2009 14:24:50 -0400 From: Greg Freemyer <greg.freemyer@...il.com> To: Kazuya Mio <k-mio@...jp.nec.com> Cc: linux-ext4@...r.kernel.org, Theodore Tso <tytso@....edu> Subject: Re: [PATCH 1/3] e4defrag: output blocks per extent by -c option 2009/10/6 Kazuya Mio <k-mio@...jp.nec.com>: > 2009/10/03 0:28, Greg Freemyer wrote:: >> 2009/10/1 Kazuya Mio <k-mio@...jp.nec.com>: >>> 2009/10/01 3:28, Greg Freemyer wrote:: >>>> 2009/9/30 Kazuya Mio <k-mio@...jp.nec.com>: >>>>> e4defrag with -c option outputs "ratio" that means the levels of >>>>> fragmentation. However, it's difficult for users to understand, so we will >>>>> use blocks per extent instead of ratio. >>>>> >>>>> Before: >>>>> # e4defrag -c /mnt/mp1/file >>>>> <File> now/best ratio >>>>> /mnt/mp1/file 14/1 0.01% >>>>> >>>>> Total/best extents 14/1 >>>>> Fragmentation ratio 0.01% >>>>> Fragmentation score 0.10 >>>>> [0-30 no problem: 31-55 a little bit fragmented: 55- needs defrag] >>>>> This file(/mnt/mp1/file) does not need defragmentation. >>>>> Done. >>>>> >>>>> After: >>>>> # e4defrag -c /mnt/mp1/file >>>>> <File> now/best blk/ext >>>>> /mnt/mp1/file 14/1 7142 >>>>> >>>>> Total/best extents 14/1 >>>>> Average blocks per extent 7142 >>>>> Fragmentation score 0 >>>>> [0-30 no problem: 31-55 a little bit fragmented: 55- needs defrag] >>>>> This file(/mnt/mp1/file) does not need defragmentation. >>>>> Done. >>>> RFC >>>> >>>> If we are going go that far (which I like), how about adding the avg >>>> extent size in bytes. (ie. 7142 * blocksize I assume). >>>> >>>> Also a note about the max blocks / extent might be good. >>>> >>>> ie. Add a more or less hard coded line >>>> Ext4 max blocks per extent 32,768 (128MiB) >>> Your ideas sound good. How about the following output image? >>> >>> # e4defrag -c /mnt/mp1/file >>> <File> now/best KB/ext >>> /mnt/mp1/file 14/1 4000 >>> >>> Total/best extents 14/1 >>> Min bytes per extent 1024 KB >>> Max bytes per extent 20489 KB >>> Average bytes per extent 4000 KB >>> Fragmentation score 0 >>> [0-30 no problem: 31-55 a little bit fragmented: 55- needs defrag] >>> This file(/mnt/mp1/file) does not need defragmentation. >>> Done. >>> >>> Regards, >>> >>> Kazuya Mio >> >> I was thinking more of the theoretical max bytes per extent, not the >> largest extent found in the actual file. >> >> I say this because most users of e4defrag won't know what perfection >> is, so they won't know if and when they have come close if they don't >> know what the ultimate goal is. >> >> Specifically, think of a admin hosting a few virtual machines where >> the virtual disks are ext4 files. They could easily be 100's of GB so >> they may think even 128MB / extent can be improved on, even though >> they have already achieved the theoretical max. >> >> Greg > > I see. But I think e4defrag doesn't always need to print logical max > bytes per extent. So, I will add it to e4defrag man page instead of > standard output. What do you think? > > Regards, > > Kazuya Mio I had not thought about the man page for some reason, but it would satisfy my concern. Greg -- Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer Preservation and Forensic processing of Exchange Repositories White Paper - <http://www.norcrossgroup.com/forms/whitepapers/tng_whitepaper_fpe.html> The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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