[Gluster-users] Problem with Gluster 3.12.4, VM and sharding

[Ing. Luca Lazzeroni - Trend Servizi Srl]

Hi to everyone.

I've got a strange problem with a gluster setup: 3 nodes with Centos 
7.4, Gluster 3.12.4 from Centos/Gluster repositories, QEMU-KVM version 
2.9.0 (compiled from RHEL sources).

I'm running volumes in replica 3 arbiter 1 mode (but I've got a volume 
in "pure" replica 3 mode too). I've applied the "virt" group settings to 
my volumes since they host VM images.

If I try to install something (eg: Ubuntu Server 16.04.3) on a VM (and 
so I generate a bit of I/O inside it) and configure KVM to access 
gluster volume directly (via libvirt), install fails after a while 
because the disk content is corrupted. If I inspect the block inside the 
disk (by accessing the image directly from outside) I can found many 
files filled with "^@".

If, instead, I configure KVM to access VM images via a FUSE mount, 
everything seems to work correctly.

Note that the problem with install is verified 100% time with QCOW2 
image, while it appears only after with RAW disk images.

Is there anyone who experienced the same problem ?

Thank you,


-- 
Ing. Luca Lazzeroni
Responsabile Ricerca e Sviluppo
Trend Servizi Srl
Tel: 0376/631761
Web: https://www.trendservizi.it