[linux-lvm] Metadata location on disk

Satish Raghunath satish_raghunath at hotmail.com
Tue Aug 16 23:37:17 UTC 2005


Hi,

I am trying to read metadata off of the COW device. I used "lvcreate -s" to 
create the snapshot and "lvdisplay" indicates that it is active and 
available. I am using hexdump on the newly created /dev/VolGroup00/lvol1 and 
I dont see the structure mentioned in dm-exception-store.c:

37  * The first chunk of the COW device just contains the header.
38  * After this there is a chunk filled with exception metadata,
39  * followed by as many exception chunks as can fit in the
40  * metadata areas.

The first 1024 bytes are all zeros. When I skip a chunk (lvdisplay indicates 
that the chunk size is 8192 bytes), I dont see the magic byte-string. Am I 
understanding this wrong? I get a similar result when I use "read" followed 
by an "open" on the COW device.

Any help will be highly appreciated.

Thank you,
Satish

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