WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-users

Re: [Xen-users] Xen Image File vs LVM

On Monday 04 August 2008 20:46:17 Chris Edwards wrote:
> Thanks for the tip.  So can I ask a few questions on setting up Xen with
> LV's?
>
>
>
> 1.        Do I need to create a separate LV for each xen guest os?
Yeap.

>
> 2.        Can you point me in the right direction for doing LV snap shots?

Not possible in current clvmd implementation.

>
> 3.        If I have a xen guest os in a LV how would I migrate the guest os
> from one machine to the other?  Create identical LV on new machine?
Using clvmd.

Best regards,

./npf


>
>
>
>
> Again, Thanks for the info.   I have been having a hard time finding the
> answers to these questions.
>
>
>
> ---
>
> Chris Edwards
> Smartech Corp.
> Div. of AirNet Group
>
> http://www.airnetgroup.com <http://www.airnetgroup.com/>
>
> http://www.smartechcorp.net <http://www.smartechcorp.net/>
>
> cedwards@xxxxxxxxxxxxxxxx <mailto:agarrison@xxxxxxxxxxxxxxxx>
> P:  423-664-7678 x114
>
> C:  423-593-6964
>
> F:  423-664-7680
>
>
>
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Grant
> McWilliams Sent: Thursday, July 31, 2008 3:35 PM
> To: Chris Edwards
> Cc: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] Xen Image File vs LVM
>
>
>
>
>
> On Thu, Jul 31, 2008 at 12:00 PM, Chris Edwards <cedwards@xxxxxxxxxxxxxxxx>
> wrote:
>
> Hello,
>
>
>
> I have been playing around with Xen for a few months now and I have not
> been able to find any information on the differences between storing a Xen
> guest OS as a image file or as a LVM.  Is there performance differences? 
> What are the pros and cons?
>
>
>
> Thanks for any help.
>
>
>
> ---
>
>
>
> Chris Edwards
>
>
>
>
> Chris,
>
> Following are two tests I did to check this very thing.
>
>
>
> Test 1 - Disk File
>
> The disk image /dev/xvdb1 was mounted as /media/test1. The images itself
> was stored on a 500 GB SATA drive. The relevent numbers are highlighted in
> blue.
>
>
>
> /dev/xvdb1            10317828    154236   9639476   2% /media/test1
>
>  [root@localhost ~]# bonnie++ -s 2048 -d /media/test1 -u root
>
> Version  1.03       ------Sequential Output------ --Sequential Input-
> --Random-
> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec
> %CP
> localhost.locald 2G  6065 15 70595 37 20649 2 26878 53 57270 0 135.8 0
> ------Sequential Create------ --------Random Create--------
> -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
> files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
> 16 17008 99 +++++ +++ 26079 90 16002 94 +++++ +++ 29094 99
> localhost.localdomain,2G,6065,15,70595,37,20649,2,26878,53,57270,0,135.8,0,
>1 6,17008,99,+++++,+++,26079,90,16002,94,+++++,+++,29094,99
>
>
>
>
> Test 2 - LVM
>
>
> The LVM Logical Volume was created on the same 500 GB SATA drive and
> mounted in the domU as /media/test2
>
> /dev/xvdc             10321208    154236   9642684   2% /media/test2
>
>
> [root@localhost ~]# bonnie++ -s 2048 -d /media/test2 -u root
>
> Version  1.03       ------Sequential Output------ --Sequential Input-
> --Random-
> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec
> %CP
> localhost.locald 2G 34825 92 50898 26 24833 4 35920 69 77594 1 137.9 0
> ------Sequential Create------ --------Random Create--------
> -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
> files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
> 16 15556 92 +++++ +++ 26198 96 16281 98 +++++ +++ 28508 100
> localhost.localdomain,2G,34825,92,50898,26,24833,4,35920,69,77594,1,137.9,0
>, 16,15556,92,+++++,+++,26198,96,16281,98,+++++,+++,28508,100
> INIT: version 2.86 reloading
>
>
>
> LVM soundly trounced the disk image in Sequential Output - Per Chr by about
> 600% and bettered it by about 20-30% in the other tests. The one
> interesting thing though was Sequential Output - Block where the disk image
> pulled ahead of LVM by about 20%. This I can't account for and will need to
> retest because it doesn't make a lot of sense. All of the Sequential
> Create/Delete stats were within 10% of each other.
>
>
>
> The advantage of files are you can use standard Linux copy and delete
> commands to manipulate them. The advantage of LVM is it's faster and you
> can benefit from LVMs ability to resize as well as create snapshots. You
> could of course do this with your disk file being on the Dom0's LVM setup
> too by utilizing the hosts LVM features.
>
>
>
> Grant McWilliams



_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users