Fajar A. Nugraha wrote:
Rudi Ahlers wrote:
Joseph L. Casale wrote:
This is for use at home, so in reality it probably doesn't matter
-- I just don't want to make any *really* stupid moves.
I would seriously recommend LVM, its so flexible
But is there really a performance difference between LVM & file based
VM's?
Yes, but depending on how you use it, the effect might not be what you
expect.
Example 1 :
- you have 16G mem : 4G for domU, 12 G for dom0
- 1 domU running, with 4G root filesystem
In this scenario, you'd most likely find file-based VM perform better
since dom0 will cache domU's root fs.
Example 2 :
- you have 8G mem : 7G for for 7 domUs (1G each), 1G for dom0
- each domU comes with 4G root filesystem
In this scenario, the performance of file-based VM will be lower
compared to LVM-based VM, due to dom0's filesystem operation overhead
(including journaling).
There are other pros and cons for file vs LVM. Personally, I prefer
LVM with each LV on dom0 maps to a partition on domU (hda1,sda1, etc)
because :
- I can easily convert a domU into a physical machine if necessary
- I can easily mount domU's fs directly on dom0 (e.g for
troubleshooting purposes)
- I can get per-LV I/O statistic from dom0 using tools like iostat
- I can use LVM snapshot to backup domU's fs without shutting it down
This setup also means that I can't create a VM using frontends like
virt-manager (which maps file/LV/partition on dom0 to a disk on domU),
but that doesn't matter since I prefer to create VMs manually using
prebuilt-template anyway :D
Regards,
Fajar
ok, what you're saying does make sense, so....
- If you say you can easily convirt a VPS to a physical machine, do you
just move the LV to a new machine?
- I can mount image based domU as well :)
- But doesn't xen have IO stats as well?
- I prefer not to use snapshot backups, since it makes it more difficult
to restore just one or two files. We mainly use cPanel & Plesk for our
hosting, so I use the control panel's backup over FTP instead
--
Kind Regards
Rudi Ahlers
CEO, SoftDux
Web: http://www.SoftDux.com
Check out my technical blog, http://blog.softdux.com for Linux or other
technical stuff, or visit http://www.WebHostingTalk.co.za for Web Hosting stuff
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