[linux-lvm] Snapshot Problem JFS
dsornig at lbmc.com
Fri Jun 20 09:30:05 UTC 2003
So to make a snapshot of the 1.4T LV which currently has a 400G of space being used by data I need to run the lvcreate command like this:
lvcreate -L1000M -s -n snap00 /dev/Volume00/LogVol00
I guess I thought the -L needed to be the same size as the current logical volume?
From: Heinz J . Mauelshagen [mailto:mauelshagen at sistina.com]
Sent: Fri 6/20/2003 4:09 AM
To: linux-lvm at sistina.com
Subject: Re: [linux-lvm] Snapshot Problem JFS
On Thu, Jun 19, 2003 at 09:07:30PM -0500, David Sornig wrote:
> I am running RedHat 9.0
> Kernel 2.4.20-8
> LVM Version 1.0.5+(22/07/2002)
> I have a 1.4T LogVol with 400G of space being used on a JFS file system.
> The LVM is working excellent. However, I cannot create a snapshot. I run the following lvcreate command as per the man page and get the following error:
> lvcreate --error "Cannot allocate memory" creating VGDA for "/dev/Volume00/snap01" in kernel
memory allocated to the snapshot needs free physical RAM.
With 400GB and default snapshot extent size we're talking about ~1GB
(using virtual memory for snapshot exception tables so that the table doesn't
need to be in RAM completely any longer is a work item for LVM2).
Do you really expect that much change to your 1.4TB LV during the lifetime of
the snapshot ?
If you use it for a backup, you might get along with a couple of GB allocated
to the snapshot reducing exception table size drastically.
> Not sure why this is happening. I have read the list and maybe I just don't understand the problem. These servers have 4 Gigs of RAM.
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
Mauelshagen at Sistina.com +49 2626 141200
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