From: Contact <neitsab@ovh.fr>
To: Theodore Ts'o <tytso@mit.edu>, lczerner@redhat.com
Cc: "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: Make huge files strictly contiguous (fallocate, bigalloc, e4defrag...)
Date: Thu, 17 Apr 2014 22:11:13 +0200 [thread overview]
Message-ID: <53503561.1060207@ovh.fr> (raw)
In-Reply-To: <5350205E.3030403@ovh.fr>
Just a little update:
Nonetheless my issues with fallocate and the bigalloc'ed fs, I tried to
dd a couple of ISOs on the key and check whether I could boot from them.
And to my great surprise... The answer was yes.
$ ls -l /run/media/neitsab/iso/_ISO/
total 4980736
drwxr-xr-x 2 neitsab users 4096 17 avril 21:38 .
drwxr-xr-x 4 neitsab users 4096 17 avril 19:36 ..
-rw------- 1 neitsab users 964689920 17 avril 21:37 gnome-3.12.iso
-rw------- 1 neitsab users 1589166080 17 avril 20:45
manjaro-gnome-0.8.9-x86_64.iso
-rw------- 1 neitsab users 993001472 17 avril 21:38
openSUSE-13.1-GNOME-Live-x86_64.iso
I can boot from the two others but not from manjaro's one, which happens
to be the biggest too. A comparison of xfs_io output :
$ xfs_io -f -c "fiemap -v"
'/run/media/neitsab/iso/_ISO/manjaro-gnome-0.8.9-x86_64.iso'
/run/media/neitsab/iso/_ISO/manjaro-gnome-0.8.9-x86_64.iso:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..262143]: 3145728..3407871 262144 0x0
1: [262144..524287]: 3407872..3670015 262144 0x0
2: [524288..786431]: 3670016..3932159 262144 0x0
3: [786432..1048575]: 3932160..4194303 262144 0x0
4: [1048576..1310719]: 4194304..4456447 262144 0x0
5: [1310720..1572863]: 4456448..4718591 262144 0x0
6: [1572864..1835007]: 5242880..5505023 262144 0x0
7: [1835008..2097151]: 5505024..5767167 262144 0x0
8: [2097152..2359295]: 5767168..6029311 262144 0x0
9: [2359296..2621439]: 6029312..6291455 262144 0x0
10: [2621440..2883583]: 6291456..6553599 262144 0x0
11: [2883584..3103839]: 6553600..6773855 220256 0x1
$ xfs_io -f -c "fiemap -v"
'/run/media/neitsab/iso/_ISO/openSUSE-13.1-GNOME-Live-x86_64.iso'
/run/media/neitsab/iso/_ISO/openSUSE-13.1-GNOME-Live-x86_64.iso:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..262143]: 8912896..9175039 262144 0x0
1: [262144..524287]: 9175040..9437183 262144 0x0
2: [524288..786431]: 9437184..9699327 262144 0x0
3: [786432..1048575]: 9699328..9961471 262144 0x0
4: [1048576..1310719]: 9961472..10223615 262144 0x0
5: [1310720..1572863]: 10223616..10485759 262144 0x0
6: [1572864..1835007]: 10485760..10747903 262144 0x0
7: [1835008..1939455]: 10747904..10852351 104448 0x1
$ xfs_io -f -c "fiemap -v" '/run/media/neitsab/iso/_ISO/gnome-3.12.iso'
/run/media/neitsab/iso/_ISO/gnome-3.12.iso:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..262143]: 6815744..7077887 262144 0x0
1: [262144..524287]: 7077888..7340031 262144 0x0
2: [524288..786431]: 7340032..7602175 262144 0x0
3: [786432..1048575]: 7602176..7864319 262144 0x0
4: [1048576..1310719]: 7864320..8126463 262144 0x0
5: [1310720..1572863]: 8126464..8388607 262144 0x0
6: [1572864..1835007]: 8388608..8650751 262144 0x0
7: [1835008..1884159]: 8650752..8699903 49152 0x1
So they're all contiguous but Manjaro. I guess that brings us back to
the randomness of block allocation as explained by Lukáš and to an
effect of file size on the probability to be non-contiguous (which is
rather logical)!
Thanks all for your explanations,
Cheers
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next prev parent reply other threads:[~2014-04-17 20:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-17 2:18 Make huge files strictly contiguous (fallocate, bigalloc, e4defrag...) Contact
2014-04-17 12:04 ` Lukáš Czerner
2014-04-17 15:24 ` Theodore Ts'o
2014-04-17 18:41 ` Contact
2014-04-17 20:11 ` Contact [this message]
2014-04-18 8:45 ` Lukáš Czerner
2014-04-20 14:37 ` Contact
2014-04-20 19:01 ` Theodore Ts'o
2014-04-20 19:38 ` Contact
2014-04-20 20:00 ` Theodore Ts'o
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