Gluster users - Apr 2015 - iscsi and distributed volume

----- Original Message -----
> From: "Roman" <romeo.r at gmail.com>
> To: gluster-users at gluster.org
> Sent: Wednesday, April 1, 2015 4:38:50 AM
> Subject: [Gluster-users] iscsi and distributed volume
> 
> Hi devs, list!
> 
> I've got somewhat simple but in same time pretty difficult question.
But I'm
> running glusterf in production and don't have any option to test myself
:(
> 
> say I've got a distributed gluster volume of 2x350GB
> I want to export ISCSI target for M$ server and I want it to be 600GB.
> I understand, that when I create a large file for ISCSI target with dd, it
> will be distributed between two bricks. And here comes the question:
> 
> What will happen when
> 
> 1. one of bricks goes down? Ok, simple - target won't be accessible.
> 2. would be data available again, when the brick comes back up? (ie failure
> due to network or power)
> 
> yes, we have backup server and ups and generator, as we are running DC, but
> I'm just curious if we will have to restore the data from backups or it
will
> be available after brick comes back up?
What kind of gluster volume is it- I would hope it is replicated? 

Data within the file is not distributed between two bricks, unless your volume
type is striped.

Assuming its replicated, if one brick went down, the other replica would
continue to operate, so you would have availability.

> 
> 
> 
> --
> Best regards,
> Roman.
> 
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org
> http://www.gluster.org/mailman/listinfo/gluster-users

You do realize you would have to put the ISCSI target disk image on
the mounted Gluster volume not directly on the brick.
So as long as you have replication your volume would remain accessible.
You can not point the ISCSI process directly to the brick or
replication and striping wont work properly.
That said you could consider using something like keepalived with a
monitoring script to handle a VIP for failover in case a node or some
of the underlying processes go down.


On Wed, Apr 1, 2015 at 10:17 AM, Dan Lambright <dlambrig at redhat.com>
wrote:
>
>
> ----- Original Message -----
>> From: "Roman" <romeo.r at gmail.com>
>> To: gluster-users at gluster.org
>> Sent: Wednesday, April 1, 2015 4:38:50 AM
>> Subject: [Gluster-users] iscsi and distributed volume
>>
>> Hi devs, list!
>>
>> I've got somewhat simple but in same time pretty difficult
question. But I'm
>> running glusterf in production and don't have any option to test
myself :(
>>
>> say I've got a distributed gluster volume of 2x350GB
>> I want to export ISCSI target for M$ server and I want it to be 600GB.
>> I understand, that when I create a large file for ISCSI target with dd,
it
>> will be distributed between two bricks. And here comes the question:
>>
>> What will happen when
>>
>> 1. one of bricks goes down? Ok, simple - target won't be
accessible.
>> 2. would be data available again, when the brick comes back up? (ie
failure
>> due to network or power)
>>
>> yes, we have backup server and ups and generator, as we are running DC,
but
>> I'm just curious if we will have to restore the data from backups
or it will
>> be available after brick comes back up?
>
> What kind of gluster volume is it- I would hope it is replicated?
>
> Data within the file is not distributed between two bricks, unless your
volume type is striped.
>
> Assuming its replicated, if one brick went down, the other replica would
continue to operate, so you would have availability.
>
>
>>
>>
>>
>> --
>> Best regards,
>> Roman.
>>
>> _______________________________________________
>> Gluster-users mailing list
>> Gluster-users at gluster.org
>> http://www.gluster.org/mailman/listinfo/gluster-users
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org
> http://www.gluster.org/mailman/listinfo/gluster-users