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Re: [Xen-users] Windows guest, swap space, separate disk?

  • To: xen-users@xxxxxxxxxxxxxxxxxxx
  • From: Brandon Lamb <brandonlamb@xxxxxxxxx>
  • Date: Thu, 18 Mar 2010 11:18:39 -0700
  • Delivery-date: Thu, 18 Mar 2010 11:24:52 -0700
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  • List-id: Xen user discussion <xen-users.lists.xensource.com>

On Thu, Mar 18, 2010 at 6:10 AM, Dustin Henning
<Dustin.Henning@xxxxxxxxxxx> wrote:
> Â Â Â ÂActually, in addition to (a), (b), and (c) below, I suppose it might 
> be possible that there would be a notable performance difference due to the 
> performance loss caused by using loop vs phy (perhaps the two separate loops 
> can be used at the same time where to negate the lost performance to some 
> degree). ÂIn that case, having multiple files might be helpful, but one image 
> would be acceptable where the procedure I previously mentioned is used for 
> setting up swap. ÂThat having been said, again, this would still mean the 5 
> GiB of swap has to be backed up as well if it wouldn't have been otherwise.
> Â Â Â ÂDustin
> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Dustin Henning
> Sent: Thursday, March 18, 2010 08:59
> To: 'Brandon Lamb'; xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-users] Windows guest, swap space, separate disk?
> Â Â Â ÂIf swap is disable, a drive is defragmented, and swap is created (say 
> 5000-5000 as you suggest), it should be one contiguous file. ÂIf it is 
> created 3500-5000 and eventually expands, then the swap will have fragments, 
> the number would depend on the fragmentation of the drive. ÂThat having been 
> said, I would argue that it is silly to make swap on a different virtual 
> drive where the two drives are the same physical drive. ÂAny OS performance 
> difference he saw was a) due to his practices b) coincidental due to the 
> location of the files in question, or c) pure placebo effect. ÂThat having 
> been said, if the user only wants to back up the drive images and isn't 
> worried about the swap images, having a separate swap image suddenly means an 
> extra 5 GiB that doesn't need copied every time there is a backup performed, 
> that could certainly constitute a performance difference (all things being 
> equal, copying a 20 GiB file will take twice as long as copying a 10GiB file).
> Â Â Â ÂDustin
> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Brandon Lamb
> Sent: Wednesday, March 17, 2010 18:06
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Windows guest, swap space, separate disk?
> Hi hopefully someone can give me a tip or a better google search query to run.
> Talking to a guy that has a vmware server setup with 20 guests, all
> xp. He set them up with a 10gig os drive (c) and a separate 5gig disk
> image (d) that he configured a 3500-5000 swap.
> Â Â Â Âa
> Now my take on this is that since all the disks are on the same
> physical disk anyway, should we just configured a single 15gig disk
> image, configure a 5000-5000 (min/max in windows) swap file for
> windows and be the same?
> He was saying he thought it was better for performance because
> otherwise the swap fragments the C:\ drive. He *claims* to have tried
> this and saw a difference.
> We plan on moving him from this vmware box with a single physical disk
> to xen with a 4 drive raid. I really dont want to screw with 2 or 3 or
> x disk images per virtual machine, management, backups etc. I told him
> i would like to just give him a single 10+swap+extra = say 20gig
> single disk image file to use.
> Comments, input please?

Wow very nice reply thank you, gives me more to think about and very
good point on not having to backup an extra 5 gigs, hmmm

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