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On Tue, Apr 28, 2009 at 6:39 PM, Duncan <1i5t5.duncan@×××.net> wrote: |
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> Nikos Chantziaras <realnc@×××××.de> posted gt7r28$cql$1@×××××××××.org, |
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> excerpted below, on Wed, 29 Apr 2009 00:05:33 +0300: |
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> |
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>> I have "defaults,noatime" and yet mount reports: |
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>> |
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>> /dev/root on / type ext4 (rw,noatime,barrier=1,data=ordered) |
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>> |
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>> Where does "rw,barrier=1,data=ordered" come from if not from "defaults"? |
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> |
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> Those (but for rw which is the normal default) are defaults of either |
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> the kernel or the filesystem itself, as set at mkfs time or with tune2fs. |
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> |
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> There's really quite a hierarchy of options and fall-thru defaults: |
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> |
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> Anything set on the mount commandline takes priority (well, after |
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> physical properties such as read-only for CDROM and floppies with write- |
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> protect set), |
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> |
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> followed by what's in fstab or the hal config, |
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> |
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> followed by options set for that particular filesystem at mkfs time or |
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> with the filesystem tuner (tun2fs, reiserfstune, whatever), |
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> |
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> followed by kernel defaults specific to that type of fs (ext3 defaulted |
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> to data=ordered but that's set to change to data=writeback in 2.6.30, |
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> after some fixes they've done but it's still rather controversial), |
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> |
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> followed by mount's normal defaults. |
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Seems root mounts get special treatment as well. Compare my / & /opt |
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- both ext4, both created identically & mounted with just noatime: |
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/dev/vg/root on / type ext4 (rw,noatime,barrier=1,data=ordered) |
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/dev/mapper/vg-opt on /opt type ext4 (rw,noatime) |
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Or perhaps its just more verbose since like Duncan said data=ordered |
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is the default & barriers are currently disabled on lvm. |
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Wil |
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