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

["Dustin Henning" <Dustin.Henning@xxxxxxxxxxx>]

        Actually, 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).  In 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.  That 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.
        Dustin

-----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?

        If swap is disable, a drive is defragmented, and swap is created (say 
5000-5000 as you suggest), it should be one contiguous file.  If it is created 
3500-5000 and eventually expands, then the swap will have fragments, the number 
would depend on the fragmentation of the drive.  That 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.  Any 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.  That 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).
        Dustin

-----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.
        a
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?

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