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Re: [Linux-cluster] Re: If I have 5 GNBD server?



On 8/27/05, brianu <brianu silvercash com> wrote:
>  
>  
> 
> Hello all, 
> 
>   
> 
> This is a question I have basically been asking, the question on why you
> would want to do it is failover, the docs at
> http://sourceware.org/cluster/gnbd/gnbd_usage.txt state
> that dm-multipath is an option for gnbd, and documents elsewhere also
> indicate that GNBD can be configured as a redundancy, yet I cannot find any
> documentation on how to configure it. 
> 
>   
> 
> If using LVM to make a volume of imported gnbds is not the answer for
> redundancy can anyone suggest a method that is? Im not opposed to using any
> other resource of cluster or GFS but I would really like to implement a
> redundant solution, ( gnbd, gulm, etc.). 
> 
Hi, Brianu, maybe LVM + md + gnbd should be one of the solution for
redundancy, for example, you have 2 gnbd servers, each one exports 1
disk. Then, the steps should be:
1. create a RAID-1  /dev/md0 on GFS client with imported 2 gnbd block devices.
2. use LVM  create /dev/vg0 on top of them.
3. mkfs_gfs on /dev/vg0.
I haven't tried this configuration, theoretically, it should work.

Thanks,

Michael
>   
> 
>   
> 
> Does anyone has an example of a redundant solution for a cluster/gfs
> filesystem i.e ( gnbd, gulm etc) ? 
> 
>   
> 
> Regards, 
> 
>   
> 
> Brian 
> 
>   
> 
> Message: 9 
> 
> Date: Fri, 26 Aug 2005 16:33:51 +0700 
> 
> From: "Fajar A. Nugraha" <fajar telkom co id> 
> 
> Subject: Re: [Linux-cluster] Re: If I have 5 GNBD server? 
> 
> To: linux clustering <linux-cluster redhat com> 
> 
> Message-ID: <430EE1FF 6050505 telkom co id> 
> 
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed 
> 
>   
> 
> Michael wrote: 
> 
>   
> 
> >Can anyone answer my question? 
> 
> >  
> 
> >  
> 
> >  
> 
> I don't think LVM cares what kind of storage it uses, as long as it's a 
> 
> block device. 
> 
> So theoretically, you can mix local disc, FC storage, GNBD, and ATOE and 
> 
> combine them using LVM. You might run into performance issues (GNBD are 
> 
> slower than FC disks) and startup issues (LVM has to start after cluster 
> 
> and gnbd-import successfuly start), but it should be possible. 
> 
>   
> 
> The real question is WHY you want to do that. 
> 
> AFAIK, if you combine 5 gnbd from 5 gnbd servers into one LVM, and you 
> 
> are accessing a volume on that volume group, and one of the gnbd server 
> 
> dies (or hangs), gnbd import will wait forever until that server is back 
> 
> up. So you'll have five more single-point-of-failures. 
> 
>   
> 
> Regards, 
> 
>   
> 
> Fajar 
> 
>   
> 
> >On 8/26/05, Michael <mikore li gmail com> wrote: 
> 
> >  
> 
> >  
> 
> >>Hi, 
> 
> >>  
> 
> >>If I have 5 gnbd servers in the network, each one export 1 block 
> 
> >>device, can I import all gnbd devices on each gfs client, and use lvm 
> 
> >>to manage them as 1 shared pool, then mkfs_gfs on it? 
> 
> >>  
> 
> >>Thanks, 
> 
> >>  
> 
> >>Michael 
> 
> >>  
> 
> >>     
> 
> >>  
> 
> >  
> 
> >  
> 
> >  
> 
>   
> 
>   
> 
>   
> 
> Brian Urrutia 
> 
> System Administrator 
> 
> Price Communications Inc. 
> 
>   There are 10 types of people in this world, 
> those who understand binary and those who don't.
>  
> 
>   
> --
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