You are seeing a side-effect of http://review.gluster.com/3631. Which means: if your backend filesystem uses 4KB blocks, then the value reported by gluster will be at worst 7 blocks smaller (4KB / 512 - 1). On Tue, Nov 26, 2013 at 3:13 AM, Maik Kulbe <info at linux-web-development.de>wrote: > So st_blocks on FUSE mount is different from st_blocks on backend for the >> same file? >> > > Yes. Just a quick example: I create a file with 5 Bytes in size. I theory > Gluster should report 8 x 512 Byte blocks, because the underlying XFS uses > a 4K block size. Instead, it reports the minimum count of blocks the file > size would fit in: > > client> echo test > /gluster/tmp/test.txt > > client> stat /gluster/tmp/test.txt > File: `/gluster/tmp/test.txt' > Size: 5 Blocks: 1 IO Block: 131072 regular file > Device: 14h/20d Inode: 12072747239032953097 Links: 1 > Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) > Access: 2013-11-26 12:09:22.960828776 +0100 > Modify: 2013-11-26 12:09:22.964828962 +0100 > Change: 2013-11-26 12:09:22.964828962 +0100 > Birth: - > > gluster> stat /bricks/0/tmp/test.txt > File: `/bricks/0/tmp/test.txt' > Size: 5 Blocks: 8 IO Block: 4096 regular file > Device: ca03h/51715d Inode: 859069733 Links: 2 > Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) > Access: 2013-11-26 12:09:22.957683891 +0100 > Modify: 2013-11-26 12:09:22.961684089 +0100 > Change: 2013-11-26 12:09:22.961684089 +0100 > Birth: - > > > >> On Nov 25, 2013 8:50 AM, "Maik Kulbe" <info at linux-web-development.de> >> wrote: >> >> 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 >> _______________________________________________ >> Gluster-users mailing list >> Gluster-users at gluster.org >> http://supercolony.gluster.org/mailman/listinfo/gluster-users >> > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://supercolony.gluster.org/pipermail/gluster-users/attachments/20131126/f30dc75d/attachment.html>
