Kernel/dmesg email addr & Converting to LVM 2

[Mark T. Valites]

On Thu, 6 Jan 2005, Cyber Source wrote:

> We've been using LVM2 for all our FC3 stuff and I really like it, the
> flexibility and the drive access speeds are fantastic. I have also seen
> a few things that might be of note. If you even e2fsck a logical volume
> that is a swap partition in LVM, it will reset the swap declaration, you
> need to mkswap again to the partition after e2fsck. I have never went
> from LVM1 to LVM2 but it would probably be a smooth transition if you
> could create the LVM2's and then tar your data in. Why are you sticking
> with 2.4 kernels? Going forward with LVM2 and staying behind with 2.4
> might have some unforseen problems, I myself have never compiled a
> kernel without forgetting a thing or two. As far as your vgimport
> problem, since you relabeled /dev/hdg (0x84), did you pvcreate /dev/hdg
> BEFORE you then tried to vgimport /dev/hdg and /dev/hdf ? I suspect
> relabeling /dev/hdg removed the pv declaration.

I don't have enough 'scratch' space to temporarily store my data on, so I
can't really create an LVM2 PV and then copy the data to it. (I do have
backups, but they're a couple hours away and doing a full restore will
take about two weeks over residential cable modem internet access).

The LVM HOWTO details how to transition an existing LVM1 setup to LVM2:

http://linux.geneseo.edu/LDP/HOWTO/LVM-HOWTO/lvm2faq.html#AEN235

Hopefully all goes well. If not, I start the backups or drive to
Binghamton and get them... - it's mostly just music, gallery photos, and
mythtv data. Sure, I *could* cutover a small test PV to LVM2, but I think
I'll choose to live dangerously for this data :)

As for the reason to stick with 2.4, this box is loaded with hardware and
does a TON, including mythtv. I really don't feel liking fighting it to
get everything working in 2.6 right now anyways. Debian back ports
devmapper into the kernels it supplies and it looks like it runs good in
2.4.

I started to keep all my kernel configs a little while ago
(http://www.valites.net/kernel_configs/) and did a 'make oldconfig' last
night from my existing 2.4.26 kernel .config. The only difference in the
configs was the added SATA support and the devmapper patch.

The pvcreate /dev/hdg was done a long time ago. Since LVM1 PVs on an
entire disk use really the entire, whole, complete disk from sector 0 on,
there really no longer is a place for an MBR, partition table and volume
ID to be kept - the part of the disk that normally holds the volume ID is
now holds LVM metadata. LVM2 metadata starts at sector 1. So, yes,
relabling the drive essentially removed the PV declaration.

-Mark

-- 
Mark T. Valites
Unix Systems Analyst
Computing & Information Technology
SUNY Geneseo
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