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Re: Reading output from "debugfs -R stat <8>"



Mike Fedyk wrote:
> 
> (0-11):506-517, (IND):518, (12-1035):519-1542, (DIND):1543, (IND):1544, (1036-2059):1545-2568, (IND):2569, (2060-3083):2570-3593, (IND):3594, (3084-4107):3595-4618, (IND):4619, (4108-5131):4620-5643, (IND):5644, (5132-6155):5645-6668, (IND):6669, (6156-7179):6670-7693, (IND):7694, (7180-8203):7695-8718, (IND):8719, (8204-9227):8720-9743, (IND):9744, (9228-10251):9745-10768, (IND):10769, (10252-11275):10770-11793, (IND):11794, (11276-12299):11795-12818, (IND):12819, (12300-13323):12820-13843, (IND):13844, (13324-14347):13845-14868, (IND):14869, (14348-15371):14870-15893, (IND):15894, (15372-16395):15895-16918, (IND):16919, (16396-17419):16920-17943, (IND):17944, (17420-18443):17945-18968, (IND):18969, (18444-19467):18970-19993, (IND):19994, (19468-20491):19995-21018, (IND):21019, (20492-21515):21020-22043, (IND):22044, (21516-22539):22045-23068, (IND):23069, (22540-23563):23070-24093, (IND):24094, (23564-24587):24095-25118, (IND):25119, (24588-25600):25120-26132
> TOTAL: 25627

Yup.  That's a perfect unfragmented file.
 
> 
> I understand the concept of inderect blocks, and double inderect blocks, but
> I don't understand the output given by this command.  Some of the numbers in
> () overlap numbers that are not in ().  Can someone explain, or point me to
> a manual that I can read?

The numbers in parentheses are the logical block numbers - the
offset into the file. The unparenthesised numbers are physical block
numbers, relative to the start of the disk partition.  So the table
is showing the logical->physical mapping for a single file.
 
> The rest of the groups average out to:
>  Group  1: block bitmap at 32770, inode bitmap at 32771, inode table at 32772
>            32267 free blocks, 15904 free inodes, 0 used directories

A block group is that number of blocks which can be managed
with a block's worth of bits in the bitmap.  I think.

So with 4k blocksize, the bitmap block has 32k bits.  So the
block group has 32k blocks.  That's 128 megabytes.

So your disk is approx 30 * 128 megabytes, I trust.  The 30 block
groups are spread evenly and linearly across the partition.





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