[Gluster-users] sparse files on EC volume

[Dmitri Chebotarov]

Hello

I'm running some tests to compare performance between Gluster FUSE mount
and formated sparse files (located on the same Gluster FUSE mount).

The Gluster volume is EC (same for both tests).

I'm seeing HUGE difference and trying to figure out why.

Here is an example:

GlusterFUSE mount:

# cd /mnt/glusterfs
# rm -f testfile1 ; dd if=/dev/zero of=testfile1 bs=1G count=1
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 9.74757 s, *110 MB/s*

Sparse file (located on GlusterFUSE mount):

# truncate -l 100GB /mnt/glusterfs/xfs-100G.img
# mkfs.xfs /mnt/glusterfs/xfs-100G.img
# mount -o loop /mnt/glusterfs/xfs-100G.img /mnt/xfs-100G
# cd /mnt/xfs-100G
# rm -f testfile1 ; dd if=/dev/zero of=testfile1 bs=1G count=1
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 1.20576 s, *891 MB/s*

The same goes for working with small files (i.e. code file, make, etc) with
the same data located on FUSE mount vs formated sparse file on the same
FUSE mount.

What would explain such difference?

How does Gluster work with sparse files in general? I may move some of the
data on gluster volumes to formated sparse files..

Thank you.
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