[CentOS] not using LVM for Linux VM guests?

Thu Nov 17 19:28:02 UTC 2011
Smithies, Russell <Russell.Smithies at agresearch.co.nz>


> -----Original Message-----
> From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On
> Behalf Of Paul Griffith
> Sent: Friday, 18 November 2011 8:04 a.m.
> To: centos at centos.org
> Subject: Re: [CentOS] not using LVM for Linux VM guests?
> 
> On 11/17/2011 11:13 AM, Jon Detert wrote:
> > Hello,
> >
> > ----- Original Message -----
> >> From: "Russell Smithies"<Russell.Smithies at agresearch.co.nz>
> >> To: "CentOS mailing list"<centos at centos.org>
> >> Sent: Wednesday, November 16, 2011 2:37:54 PM
> >> Subject: [CentOS] not using LVM for Linux VM guests?
> >>
> >> I came across an old post comment yesterday (from
> >> http://echenh.blogspot.com/2010/04/how-to-extend-lvm-on-vmware-
> guest-
> >> os.html
> >> ) discussing the "hack" of LVM on Linux VM guests and whether it's
> >> better not to use it to simplify disk management.
> >> I've re-posted the comment below, does it sound reasonable? Is it
> >> better to not use LVM on Linux VM guests?
> >>
> >> --Russell
> >
> > I've had the same question.  I've decided to continue to use LVM, for these
> 2 reasons:
> >
> > 1) my hypervisor, good, bad or indifferent, is VMware ESX 4.x and ESXi 4.x.
> Those hypervisors can't create virtual disks greater than 256 GB.  So, if I want
> a file-system larger than 256 GB, I have to have some other software - LVM,
> in this case.
> 
> Just to clarify one thing with large virtual disks. The size limitation is
> determined by the block size.
> 
> To create a file bigger than 256GB, the VMFS filesystem needs to have a
> block size larger than 1MB. These are the maximums:
> 
> VMFS-3 (ESX/ESXi 4.x)
> 
> Block Size Maximum File Size
> 1 MB - 256 GB (default)
> 2 MB - 512 GB
> 4 MB - 1 TB
> 8 MB - 2 TB
> 
> http://kb.vmware.com/kb/1003565
> 
> With VMFS-5 has a maximum virtual disk size of 2TB minus 512B, with a 1 MB
> block size.
> 
> Cheers,
> Paul

I just did the vSphere 5 "What's New" course and it looked they'd pumped all the maximums up to usable levels now.
Be nice if they could decide on a licensing model that made more sense...

--Russell
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