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<div class="moz-cite-prefix">On 05/18/2017 10:35 AM,
TranceWorldLogic . wrote:<br>
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cite="mid:CAOtQfMT_heSqRH-cgDP2W58_oVToD4XP6w35Tjm0_8zH8wNV1Q@mail.gmail.com"
type="cite">
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<div>Thanks,<br>
</div>
Would you also explain about my 2nd question ?<br>
<br>
</div>
let say hostB mounted glusterFS partition by using backup
vol (e.g. hostB) and after some time Host A come online,
will GlusterFS client (mount) automatically switch to Host A
?<br>
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</blockquote>
mount will not switch automatically to Host A .<br>
<br>
In an ideal case i.e with out using backup-vol-file-server option if
host B goes down, you mount will not be accessible since host B went
down and df -TH or mount does not show the volume or it says
"Transport End point not connected".<br>
<br>
Take the case where using backup-volfile-server option. If host B
goes down, your mount will still be accessible since there is
backup-volfile-server and df -TH or mount still shows that volume is
mounted using Host B, but all the internal requests will be served
through Host A.<br>
<br>
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cite="mid:CAOtQfMT_heSqRH-cgDP2W58_oVToD4XP6w35Tjm0_8zH8wNV1Q@mail.gmail.com"
type="cite">
<div class="gmail_extra"><br>
<div class="gmail_quote">On Thu, May 18, 2017 at 9:43 AM, knarra
<span dir="ltr"><<a moz-do-not-send="true"
href="mailto:knarra@redhat.com" target="_blank">knarra@redhat.com</a>></span>
wrote:<br>
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<div class="m_-7509900777764793872moz-cite-prefix">Hi,<br>
<br>
backup-volfile-servers is mainly used to avoid SPOF.
For example take a scenario where you have Host A and
Host B and when you try to mount a glusterfs volume
using Host A with backup-volfile-servers specified, if
Host A is not accessible, mount will happen with Host B
which is specified in backup-volfile-server.
backup-volfile-servers are mainly used to fetch the
volfile from gluster and has nothing to do with data
sync. <br>
<br>
data syncing comes as part of replicate feature in
glusterfs where say for example, you have two Hosts Host
A and Host B with replica volume configured, if Host A
goes down for sometime, all the writes happens on Host B
and when Host A comes up data gets synced to HostA. <br>
<br>
Hope this helps !!!!<br>
<br>
Thanks<br>
kasturi
<div>
<div class="h5"><br>
<br>
On 05/17/2017 11:31 PM, TranceWorldLogic . wrote:<br>
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<div>Hi,<br>
<br>
</div>
Before trying out, I want to understand how
glusterfs will react for below scenario.<br>
</div>
<div>Please help me.<br>
</div>
<div><br>
</div>
Let consider I have two host hostA and hostB<br>
</div>
I have setup replica volume on hostA and hostB.
(consider as storage domain for DATA in ovirt).<br>
</div>
I have configure data domain mount command with
backup server option (backup-volfile-server) as
hostB (I mean main server as hostA and backup as
hostB)<br>
<div><br>
</div>
<div>1> As I understood, VDSM execute mount
command on both hostA and hostB.(for creating
data domain)<br>
</div>
<div>2> That mean, HostB glusterFS CLIENT will
communicate with main server (hostA).<br>
</div>
<div>(Please correct me if I am wrong here.)<br>
</div>
<div>3> Let say HostA got down (say shutdown,
power off scenario)<br>
</div>
<div>4> Due to backup option I will have data
domain available on HostB.<br>
</div>
<div>(Now glusterFS CLIENT on HostB will start
communicating with HostB GlusterFS SERVER).<br>
</div>
<div>5> Now let say HostA comes up.<br>
</div>
<div>6> Will it sync all data from HostB to
HostA glusterFS server ?<br>
</div>
<div>(as per doc, yes, i not tried yet, want to
confirm my understanding)<br>
</div>
<div>7> Will glusterFS CLIENT on HostB start
communicate with main server (HostA) ?<br>
<br>
</div>
<div>Please let me know, I am new to glusterFS.<br>
<br>
</div>
<div>Thanks,<br>
</div>
<div>~Rohit<br>
</div>
</div>
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