Mailing List Archive


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [tlug] server partitions, LVM, and Xen



Micheal Cooper kirjoitti 2007/05/22 kello 17:50:
At first, I was thinking about having an RHEL5 Xen host with a database server in a VM as a file. I started thinking about a VM for the database server because it requires PHP4, and RHEL5 uses PHP5. Then I realized that I could just copy the file over to another machine as a backup for the OS. With daily database dumps and backups of the database webapp files, I would have a two-step recovery for disasters: 1-copy VM over to Xen host; 2-restore the latest dump file.

Hi Micheal,

If your hardware is fast and you use paravirtualization, the file based approach
is very simple and performs well.
For the backups, realize that you probably will have to shutdown the virtual
domain to create a good snapshot.


With LVM, you can supposedly snapshot the whole live filesystem, but never tried that.

A file server would be a harder sell as a VM, but the same principle applies: the OS is a single file that is backed up to another machine or HDD, but the data would have to live in a partition on the host and be backed up (rsync) to a backup server nightly. The restore would still be two-part, though. You move the backed-up OS VM file to a Xen host and then copy the data from the backup server to a partition on the host.

However, I suspect that it is scarier than it seems (and it seems kinda scary). Is anyone doing anything like this?

I don't see why that would be tricky. You can mount the exportable filesystem from somewhere else, an
LVM or a normal partition with an ext3 filesystem. Backing that up just involves making sure the
filesystem integrity is preserved.


The advantage with XEN with these server scenarios is that after your image is to your liking, you
can shutdown the domain, store a backup and the xen-config, and quickly make clones or restore
a working virtual machine.


BTW, my suggestion for the XEN domain0 partition scheme is to go with a single 1-2GB partition and swap.
The rest of the disk should be reserved for LVM (for flexible storage, domains etc..)


My 2jpy ;-)

--
Henri



Home | Main Index | Thread Index

Home Page Mailing List Linux and Japan TLUG Members Links