[Gluster-users] GlusterFS as virtual machine storage

Thu Sep 7 18:06:19 UTC 2017

Hi Neil, docs mention two live nodes of replica 3 blaming each other and
refusing to do IO.

https://gluster.readthedocs.io/en/latest/Administrator%20Guide/Split%20brain%20and%20ways%20to%20deal%20with%20it/#1-replica-3-volume

On Sep 7, 2017 17:52, "Alastair Neil" <ajneil.tech at gmail.com> wrote:

> *shrug* I don't use arbiter for vm work loads just straight replica 3.
> There are some gotchas with using an arbiter for VM workloads.  If
> quorum-type is auto and a brick that is not the arbiter drop out then if
> the up brick is dirty as far as the arbiter is concerned i.e. the only good
> copy is on the down brick you will get ENOTCONN and your VMs will halt on
> IO.
>
> On 6 September 2017 at 16:06, <lemonnierk at ulrar.net> wrote:
>
>> Mh, I never had to do that and I never had that problem. Is that an
>> arbiter specific thing ? With replica 3 it just works.
>>
>> On Wed, Sep 06, 2017 at 03:59:14PM -0400, Alastair Neil wrote:
>> > you need to set
>> >
>> > cluster.server-quorum-ratio             51%
>> >
>> > On 6 September 2017 at 10:12, Pavel Szalbot <pavel.szalbot at gmail.com>
>> wrote:
>> >
>> > > Hi all,
>> > >
>> > > I have promised to do some testing and I finally find some time and
>> > > infrastructure.
>> > >
>> > > So I have 3 servers with Gluster 3.10.5 on CentOS 7. I created
>> > > replicated volume with arbiter (2+1) and VM on KVM (via Openstack)
>> > > with disk accessible through gfapi. Volume group is set to virt
>> > > (gluster volume set gv_openstack_1 virt). VM runs current (all
>> > > packages updated) Ubuntu Xenial.
>> > >
>> > > I set up following fio job:
>> > >
>> > > [job1]
>> > > ioengine=libaio
>> > > size=1g
>> > > loops=16
>> > > bs=512k
>> > > direct=1
>> > > filename=/tmp/fio.data2
>> > >
>> > > When I run fio fio.job and reboot one of the data nodes, IO statistics
>> > > reported by fio drop to 0KB/0KB and 0 IOPS. After a while, root
>> > > filesystem gets remounted as read-only.
>> > >
>> > > If you care about infrastructure, setup details etc., do not hesitate
>> to
>> > > ask.
>> > >
>> > > Gluster info on volume:
>> > >
>> > > Volume Name: gv_openstack_1
>> > > Type: Replicate
>> > > Volume ID: 2425ae63-3765-4b5e-915b-e132e0d3fff1
>> > > Status: Started
>> > > Snapshot Count: 0
>> > > Number of Bricks: 1 x (2 + 1) = 3
>> > > Transport-type: tcp
>> > > Bricks:
>> > > Brick1: gfs-2.san:/export/gfs/gv_1
>> > > Brick2: gfs-3.san:/export/gfs/gv_1
>> > > Brick3: docker3.san:/export/gfs/gv_1 (arbiter)
>> > > Options Reconfigured:
>> > > nfs.disable: on
>> > > transport.address-family: inet
>> > > performance.quick-read: off
>> > > performance.read-ahead: off
>> > > performance.io-cache: off
>> > > performance.stat-prefetch: off
>> > > performance.low-prio-threads: 32
>> > > network.remote-dio: enable
>> > > cluster.eager-lock: enable
>> > > cluster.quorum-type: auto
>> > > cluster.server-quorum-type: server
>> > > cluster.data-self-heal-algorithm: full
>> > > cluster.locking-scheme: granular
>> > > cluster.shd-max-threads: 8
>> > > cluster.shd-wait-qlength: 10000
>> > > features.shard: on
>> > > user.cifs: off
>> > >
>> > > Partial KVM XML dump:
>> > >
>> > >     <disk type='network' device='disk'>
>> > >       <driver name='qemu' type='raw' cache='none'/>
>> > >       <source protocol='gluster'
>> > > name='gv_openstack_1/volume-77ebfd13-6a92-4f38-b036-e9e55d752e1e'>
>> > >         <host name='10.0.1.201' port='24007'/>
>> > >       </source>
>> > >       <backingStore/>
>> > >       <target dev='vda' bus='virtio'/>
>> > >       <serial>77ebfd13-6a92-4f38-b036-e9e55d752e1e</serial>
>> > >       <alias name='virtio-disk0'/>
>> > >       <address type='pci' domain='0x0000' bus='0x00' slot='0x04'
>> > > function='0x0'/>
>> > >     </disk>
>> > >
>> > > Networking is LACP on data nodes, stack of Juniper EX4550's (10Gbps
>> > > SFP+), separate VLAN for Gluster traffic, SSD only on Gluster all
>> > > nodes (including arbiter).
>> > >
>> > > I would really love to know what am I doing wrong, because this is my
>> > > experience with Gluster for a long time a and a reason I would not
>> > > recommend it as VM storage backend in production environment where you
>> > > cannot start/stop VMs on your own (e.g. providing private clouds for
>> > > customers).
>> > > -ps
>> > >
>> > >
>> > > On Sun, Sep 3, 2017 at 10:21 PM, Gionatan Danti <g.danti at assyoma.it>
>> > > wrote:
>> > > > Il 30-08-2017 17:07 Ivan Rossi ha scritto:
>> > > >>
>> > > >> There has ben a bug associated to sharding that led to VM
>> corruption
>> > > >> that has been around for a long time (difficult to reproduce I
>> > > >> understood). I have not seen reports on that for some time after
>> the
>> > > >> last fix, so hopefully now VM hosting is stable.
>> > > >
>> > > >
>> > > > Mmmm... this is precisely the kind of bug that scares me... data
>> > > corruption
>> > > > :|
>> > > > Any more information on what causes it and how to resolve? Even if
>> in
>> > > newer
>> > > > Gluster releases it is a solved bug, knowledge on how to treat it
>> would
>> > > be
>> > > > valuable.
>> > > >
>> > > >
>> > > > Thanks.
>> > > >
>> > > > --
>> > > > Danti Gionatan
>> > > > Supporto Tecnico
>> > > > Assyoma S.r.l. - www.assyoma.it
>> > > > email: g.danti at assyoma.it - info at assyoma.it
>> > > > GPG public key ID: FF5F32A8
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