* [linux-lvm] Snapshot Problem JFS
@ 2003-06-19 21:08 David Sornig
2003-06-20 4:23 ` Heinz J . Mauelshagen
0 siblings, 1 reply; 6+ messages in thread
From: David Sornig @ 2003-06-19 21:08 UTC (permalink / raw)
To: linux-lvm
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
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.
Regards,
David
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] Snapshot Problem JFS
2003-06-19 21:08 [linux-lvm] Snapshot Problem JFS David Sornig
@ 2003-06-20 4:23 ` Heinz J . Mauelshagen
0 siblings, 0 replies; 6+ messages in thread
From: Heinz J . Mauelshagen @ 2003-06-20 4:23 UTC (permalink / raw)
To: linux-lvm
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
>
David,
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.
>
> Regards,
>
> David
--
Regards,
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
56242 Marienrachdorf
Germany
Mauelshagen@Sistina.com +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [linux-lvm] Snapshot Problem JFS
@ 2003-06-20 9:30 David Sornig
2003-06-20 10:04 ` Heinz J . Mauelshagen
0 siblings, 1 reply; 6+ messages in thread
From: David Sornig @ 2003-06-20 9:30 UTC (permalink / raw)
To: linux-lvm
[-- Attachment #1: Type: text/plain, Size: 2710 bytes --]
Heinz,
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?
Thanks,
David
-----Original Message-----
From: Heinz J . Mauelshagen [mailto:mauelshagen@sistina.com]
Sent: Fri 6/20/2003 4:09 AM
To: linux-lvm@sistina.com
Cc:
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
>
David,
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.
>
> Regards,
>
> David
--
Regards,
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
56242 Marienrachdorf
Germany
Mauelshagen@Sistina.com +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
_______________________________________________
linux-lvm mailing list
linux-lvm@sistina.com
http://lists.sistina.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
[-- Attachment #2: winmail.dat --]
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] Snapshot Problem JFS
2003-06-20 9:30 David Sornig
@ 2003-06-20 10:04 ` Heinz J . Mauelshagen
0 siblings, 0 replies; 6+ messages in thread
From: Heinz J . Mauelshagen @ 2003-06-20 10:04 UTC (permalink / raw)
To: linux-lvm
On Fri, Jun 20, 2003 at 06:43:40AM -0500, David Sornig wrote:
> Heinz,
>
> 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
Yes, if you want to have a snapshot with a 1000MB exception store.
>
> I guess I thought the -L needed to be the same size as the current logical volume?
No, it doesn't need unless you have an update ratio of 100% to the original
during the lifetime of the snapshot. As a rule of thumb you can assume 5%
(which would be ~71g in your case) but that heavily depends on your
usage of the filesystem for obvious reasons.
You can use lvdisplay on the snapshot to retrieve how much space is in use
and if it becomes full, you can lvextend it.
Regards,
Heinz -- The LVM Guy --
>
> Thanks,
>
> David
>
>
> -----Original Message-----
> From: Heinz J . Mauelshagen [mailto:mauelshagen@sistina.com]
> Sent: Fri 6/20/2003 4:09 AM
> To: linux-lvm@sistina.com
> Cc:
> 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
> >
>
> David,
>
> 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.
> >
> > Regards,
> >
> > David
>
> --
>
> Regards,
> Heinz -- The LVM Guy --
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
*** 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
56242 Marienrachdorf
Germany
Mauelshagen@Sistina.com +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [linux-lvm] Snapshot Problem JFS
@ 2003-06-23 8:10 David Sornig
2003-06-23 9:24 ` Heinz J . Mauelshagen
0 siblings, 1 reply; 6+ messages in thread
From: David Sornig @ 2003-06-23 8:10 UTC (permalink / raw)
To: linux-lvm
[-- Attachment #1: Type: text/plain, Size: 5038 bytes --]
Heinz,
Thank you for your help. Just want to make sure I understand perfectly what should happen.
I have a Volume group with 4.2 T of space. In this Volume Group I have a Logical Volume called LogVol00 that is 1.4 T in size. Currently the LogVol has 400G of Data on it. In order to allow for approx 5% growth I need a snapshot of 420G or 1.470T. This is were I am confused.
so I think I need the follwoing command. I am not in front of the system to test this so I am asking before I go forward since our live data is on this server.
lvcreate - L 1.470T -s -n snap00 /dev/Volume00/LogVol00
The reason I am trying to clarify is that I will be creating and destroying these using scripts and I do not want to have aproblem down the road without fully understanding.
Thanks again for all of your help and sorry for being such a stickler for details.
David
-----Original Message-----
From: Heinz J . Mauelshagen [mailto:mauelshagen@sistina.com]
Sent: Fri 6/20/2003 9:50 AM
To: linux-lvm@sistina.com
Cc:
Subject: Re: [linux-lvm] Snapshot Problem JFS
On Fri, Jun 20, 2003 at 06:43:40AM -0500, David Sornig wrote:
> Heinz,
>
> 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
Yes, if you want to have a snapshot with a 1000MB exception store.
>
> I guess I thought the -L needed to be the same size as the current logical volume?
No, it doesn't need unless you have an update ratio of 100% to the original
during the lifetime of the snapshot. As a rule of thumb you can assume 5%
(which would be ~71g in your case) but that heavily depends on your
usage of the filesystem for obvious reasons.
You can use lvdisplay on the snapshot to retrieve how much space is in use
and if it becomes full, you can lvextend it.
Regards,
Heinz -- The LVM Guy --
>
> Thanks,
>
> David
>
>
> -----Original Message-----
> From: Heinz J . Mauelshagen [mailto:mauelshagen@sistina.com]
> Sent: Fri 6/20/2003 4:09 AM
> To: linux-lvm@sistina.com
> Cc:
> 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
> >
>
> David,
>
> 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.
> >
> > Regards,
> >
> > David
>
> --
>
> Regards,
> Heinz -- The LVM Guy --
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
*** 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
56242 Marienrachdorf
Germany
Mauelshagen@Sistina.com +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
_______________________________________________
linux-lvm mailing list
linux-lvm@sistina.com
http://lists.sistina.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
[-- Attachment #2: winmail.dat --]
[-- Type: application/ms-tnef, Size: 11586 bytes --]
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] Snapshot Problem JFS
2003-06-23 8:10 David Sornig
@ 2003-06-23 9:24 ` Heinz J . Mauelshagen
0 siblings, 0 replies; 6+ messages in thread
From: Heinz J . Mauelshagen @ 2003-06-23 9:24 UTC (permalink / raw)
To: linux-lvm
On Fri, Jun 20, 2003 at 12:29:15PM -0500, David Sornig wrote:
> Heinz,
>
> Thank you for your help. Just want to make sure I understand perfectly what should happen.
>
> I have a Volume group with 4.2 T of space. In this Volume Group I have a Logical Volume called LogVol00 that is 1.4 T in size. Currently the LogVol has 400G of Data on it. In order to allow for approx 5% growth I need a snapshot of 420G or 1.470T. This is were I am confused.
>
If you want to allow for 5% changes on the original LV (1.4 TB), you
want a snapshot size of 70 GB. Please remember: the snapshot only stores
the changes to the original LV.
> so I think I need the follwoing command. I am not in front of the system to test this so I am asking before I go forward since our live data is on this server.
>
> lvcreate - L 1.470T -s -n snap00 /dev/Volume00/LogVol00
lvcreate -L 70G -s -n snap00 /dev/Volume00/LogVol00
>
> The reason I am trying to clarify is that I will be creating and destroying these using scripts and I do not want to have aproblem down the road without fully understanding.
>
You can check with "lvdisplay /dev/Volume00/snap00" hw much space is
already used and if space isn't sufficient, you can grow it with lvextend.
Regards,
Heinz -- The LVM Guy --
> Thanks again for all of your help and sorry for being such a stickler for details.
>
> David
>
> -----Original Message-----
> From: Heinz J . Mauelshagen [mailto:mauelshagen@sistina.com]
> Sent: Fri 6/20/2003 9:50 AM
> To: linux-lvm@sistina.com
> Cc:
> Subject: Re: [linux-lvm] Snapshot Problem JFS
>
>
>
> On Fri, Jun 20, 2003 at 06:43:40AM -0500, David Sornig wrote:
> > Heinz,
> >
> > 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
>
> Yes, if you want to have a snapshot with a 1000MB exception store.
>
> >
> > I guess I thought the -L needed to be the same size as the current logical volume?
>
> No, it doesn't need unless you have an update ratio of 100% to the original
> during the lifetime of the snapshot. As a rule of thumb you can assume 5%
> (which would be ~71g in your case) but that heavily depends on your
> usage of the filesystem for obvious reasons.
>
> You can use lvdisplay on the snapshot to retrieve how much space is in use
> and if it becomes full, you can lvextend it.
>
> Regards,
> Heinz -- The LVM Guy --
>
>
> >
> > Thanks,
> >
> > David
> >
> >
> > -----Original Message-----
> > From: Heinz J . Mauelshagen [mailto:mauelshagen@sistina.com]
> > Sent: Fri 6/20/2003 4:09 AM
> > To: linux-lvm@sistina.com
> > Cc:
> > 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
> > >
> >
> > David,
> >
> > 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.
> > >
> > > Regards,
> > >
> > > David
> >
> > --
> >
> > Regards,
> > Heinz -- The LVM Guy --
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm@sistina.com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> >
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
>
*** 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
56242 Marienrachdorf
Germany
Mauelshagen@Sistina.com +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
^ permalink raw reply [flat|nested] 6+ messages in thread
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Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2003-06-20 9:30 David Sornig
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