[ale] Xen Server adding a virtual disk to a VM

[DJ-Pfulio]

Ok, so fdisk was patched, but I'm still waiting for that patch to
actually make it into every distro I see. I keep seeing fdisk complain
about GPT disks - easier to just use parted, IMHO. Parted also aligns
partitions correctly, as does gparted.  fdisk does not. If you use only
SSDs, don't think that it matters, but on spinning disks, there can be a
real, noticeable, performance hit.

GPT has many upgrades over MBR, like duplication at the front/end of the
storage, not only at the beginning. Plus not having to deal with
"logical/extended" partitions ever again is nice. Wikipdeia has more.

Inside a VM, I don't don't use LVM.  Only outside on the hostOS. There
are multiple pros/cons to either method. I can understand if folks want
LVM inside a VM and why they wouldn't. Do some research.

Haven't touched btrfs. Seems there is always some "issue" that is
important to me with it. Whether that is true or not is completely
irrelevant. It is a hassle that I don't need. Understand many people
love btrfs, which is great. More users will eventually fix the issues I
have! Thanks!

I've never had an issue with my HW NOT supporting GPT. Linux has since
before 2010.  There might be some poorly written BIOS which get confused
... because Windows **only** supports booting off GPT disks with UEFI +
64-bit OS.  Those are Windows limitations and have nothing to do with
Linux.  For non-booting disks, gpt has been supported by all OSes since
2008-ish, I believe.

lsblk is nice. Plus, it doesn't need sudo to work (at least not on any
systems I manage).


On 10/14/2016 12:23 PM, Scott Plante wrote:
> Ah ha, very interesting. I was vaguely aware of GPT but I've never used
> parted before just now. I know GPT is (generally) needed for disks
> larger than 2TB, but should I use it all the time now, even for virtual
> disks inside a Xen VM? 
> 
> For that matter, if I'm creating a virtual disk to give to a VM, is
> there any reason to partition it with anything? I've been creating one
> partition and then creating the filesystem in the partition. I just
> create separate virtual disks for what I would have used partitions for
> in the past--so for example the main OS is on one virtual disk, /opt is
> on another, and each disk has one partition. I saw a btrfs tutorial
> yesterday where they were just using the whole unpartitioned disk, and
> it made me wonder why I was should partitionVM disks, other than habit.
> 
> On GPT / 2TB drive limits, how can you tell if the hardware & BIOS will
> support GPT and/or drives larger than 2TB?
> 
> The lsblk looks very cool, ty DJ!
> 
> Scott
> 
> p.s. I just learned that fdisk was patched in June 2012, for v2.3.1, to
> support GPT! Of course, that's of little use to me since CentOS 7 still
> has 2.23.7 as the latest available version.
> https://git.kernel.org/cgit/utils/util-linux/util-linux.git/commit/?id=766d5156c43b784700d28d1c1141008b2bf35ed7
> 
> ------------------------------------------------------------------------
> *From: *"DJ-Pfulio" <DJPfulio at jdpfu.com>
> *To: *"Atlanta Linux Enthusiasts" <ale at ale.org>
> *Sent: *Friday, October 14, 2016 6:23:17 AM
> *Subject: *Re: [ale] Xen Server adding a virtual disk to a VM
> 
> fdisk doesn't handle GPT partitions.
> Use parted instead.
> 
> lsblk
> lvs
> vgs
> pvs
> 
> are handy too.
> 
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