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Re: [Xen-users] XCP storage repository using VHD on top of the LVM (FC shared too) instead of the NFS.

  • To: Dave Scott <Dave.Scott@xxxxxxxxxxxxx>
  • From: Martinx - ジェームズ <thiagocmartinsc@xxxxxxxxx>
  • Date: Thu, 25 Mar 2010 17:15:51 -0300
  • Cc: Xen List <xen-users@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Thu, 25 Mar 2010 13:17:19 -0700
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On 24 March 2010 18:54, Dave Scott <Dave.Scott@xxxxxxxxxxxxx> wrote:



XCP does use VHD format on top of the LVs it creates on iSCSI/FC storage. The current problem is that it doesn’t support “thin provisioning” (i.e. not pre-allocating). It’s great for making snapshots and clones but not so good for space usage… as you observed!

Completely understood...


There is an early prototype of an XCP/vhd storage daemon which has an LVM implementation optimized for being able to quickly resize volumes. When that stabilizes, we’ll be able to have thin provisioning. We should put the development repo for the prototype on xenbits somewhere.

Mmm... You mean this thin provisioning is, in fact, a grow of the logical volume when it becomes, for example, 95% full?

I'm thinking in a more simple way to do it, looking at the way the XCP does the mount of the NFS Server and makes its shared repository there, I think: Why they just don't mount a big (1T) local logical volume and make the necessary files (storage repo and the VHDs) on the locally mounted file system, instead of the remote NFS?

Also, we can use the SDFS instead of the ext3 for the logical volume file system, so we can save more disc space!

I'll try this SDFS this week, to export it through NFS to a XCP node and sees how fast and secure it is...

Look: http://www.opendedup.org





From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Martinx - ?????
Sent: 23 March 2010 20:47
To: Xen List
Subject: [Xen-users] XCP storage repository using VHD on top of the LVM (FC shared too) instead of the NFS.



 I thinking why the XCP/XenServer has an option to use the VHD format only for the NFS Servers... How to use the VHD on top of a local or shared LVM?

 I mean, I want to create a logical volume of 500G and within this volume, I'll create the VHDs files instead LVs for each domU.

 And I'll use this setup on top of my FC IBM DS4700 shared storage...

 It is possible?! I want the good of both worlds, the space efficient feature of the VHDs (not pre-allocating) with the speed of the local or fiber channel storage.


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