[Gluster-users] Block size reported from FUSE-client

Maik Kulbe info at linux-web-development.de
Mon Nov 25 16:50:19 UTC 2013


> From man (2) stat:
>
> blksize_t st_blksize; /* blocksize for file system I/O */
> blkcnt_t  st_blocks;  /* number of 512B blocks allocated */
>
> The 128K  you are seeing is "st_blksize" which is the recommended I/O
> transfer size. The number of consumed blocks is always reported as 512
> byte blocks. The actual block size with which storage allocation happens
> depends on the backend filesystem.

This is what was confusing me. On the file systems one of our programmers tested the latter one it was always showing the blocks allocated. So if you had a 1k file and 4k block size it would report 8 512-byte blocks, gluster just reports 2 blocks.

> Avati
>
> On Mon, Nov 25, 2013 at 7:18 AM, Maik Kulbe
> <info at linux-web-development.de> wrote:
>
> Hi,
>
> I've come to notice that the file system block size reported from stat
> on a client is 128k, which is pretty high for the small files I use. On
> the other hand, I tested copying smaller files to the volume and it
> seems those 128k are not the real block size - when I copy two 64k files
> to the volume `df` reports only a change after both files have been
> copied.
>
> So my question would be what is the real block size for the Gluster
> volume? The block size of the underlying xfs? Or something else? And is
> it possible to read the real block size? We wanted to use the block size
> reported by stat to calculate the real file size use on disk but it
> seems that is not possible with Gluster..
>
> Thank you in advance,
> Maik
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