All geek questions in one place

What is the degree (in FS)?

I played with Linux the new FS, BTRFS and did some research on this. BTRFS, like Ext4, implements extents as a unit for the distribution of data and metadata. So, my understanding (correct me if I'm worng) that the degree is a variable contignuos block space size. My question is ... is there a single file stored on the same level or several ... or do they have groups of different sizes? I'm not quite sure how they map to blocks ...

Thank!

+3
source share
2 answers

Yes, a degree is an adjacent group of blocks. Distribution Size (4 KB, etc.) Determines how large one degree can be. Thus, two things can cause the file to have several extents: 1) the file is larger than the largest contiguous free space, and 2) the file is larger than the maximum possible size supported by the selection size.

+1
source

size is the size of the contignuos variable space

Yes.

- one file stored on one level or several ... or they have groups of different sizes

It depends on how fragmented the file is.

From the BTRFS wiki glossary :

degrees of

  • An adjacent sequence of bytes on disk containing file data.

  • , 3 , , . . Filefrag. , .

filefrag

  • , , . e2fsprogs Linux. ext2, Btrfs ( ). FIEMAP ioctl.

, 15 22 . ( , , .)

4096 (1 ).

+1

Source: https://habr.com/ru/post/1769732/

More articles:


All Articles