[sheepdog-users] sheepdog replica number question

Walid Moghrabi walid.moghrabi at lezard-visuel.com
Mon May 5 18:11:25 CEST 2014

Well, this is mainly because some frontends (such as ProxMox when used in conjunction with Sheepdog as a backend storage) doesn't provide the ability to change that value from the GUI at VM creation. 
So, if you want another number of copies, you have to create the vdi first, then the VM with no hard drive (but you can't so you create a dummy hard drive), then modify the VM to delete the dummy drive and attach your previously created vdi. 

Also, since Sheepdog is very flexible, it is not rare to begin your cluster with only 2 nodes where you usually format your cluster with -c 2 so that you're doing pure replication between nodes then later, you add new nodes and in that case, you would be happy to renumber your whole cluster to -c 3 so that every vdi you already created create a new copy and every new vdi is -c 3 by default so that you don't have to thing to create them with the good number copy (especially when your frontend is a bit dumb for that job since it doesn't provide you with the functions you need and you have to waste time with workarounds). 



----- Mail original -----

De: "Andrew J. Hobbs" <ajhobbs at desu.edu> 
À: sheepdog-users at lists.wpkg.org 
Envoyé: Lundi 5 Mai 2014 18:01:36 
Objet: Re: [sheepdog-users] sheepdog replica number question 

I would prefer the default be immutable for a given format, this is primarily because it's trivial to alter the number of copies at vdi creation time, or even use erasure coding depending on need. The default should remain something sensible such as 3 simply as a guard for me forgetting to specify the copy count at creation time. 

Not sure how useful in-place would be. It's trivial to write out and read back an image in a different format. 

On 05/05/2014 05:20 AM, Walid Moghrabi wrote: 

I know this has already been asked before but is it planned to be able to change the default cluster format setting afterward ? 
2 cases would be nice to take care of : 
* change de default cluster format number so that new vdi use this new default value (pretty easy I guess) 
* renumber, after many warnings, existing vdi copies so that a vdi that has been created with -c 2 can be upgraded to -c 3 for example 



De: "Liu Yuan" <namei.unix at gmail.com><mailto:namei.unix at gmail.com> 
À: "飞" <duron800 at qq.com><mailto:duron800 at qq.com> 
Cc: "sheepdog-users" <sheepdog-users at lists.wpkg.org><mailto:sheepdog-users at lists.wpkg.org> 
Envoyé: Lundi 5 Mai 2014 05:11:35 
Objet: Re: [sheepdog-users] sheepdog replica number question 

On Mon, May 05, 2014 at 09:28:41AM +0800, 飞 wrote: 
> hello, I have deployed sheepdog for test, and I format the cluster with 3 replica,but if I want to change the replica number of cluster or VDI, how to change it ? thank you. 

You can create a vdi with whatever copies you want as following: 

dog vdi create -c x your_vdi 100G 

Sheepdog support different copies per vdi for a single cluster. 

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