[pve-devel] Error between PVE and LVM
Cesar Peschiera
brain at click.com.py
Sat Nov 29 19:20:03 CET 2014
Hi Daniel
Thanks for your clarification, it is good know it, and please let me to do some comments:
About of do to grow the max the VD of the VM: as a administration strategy, if my hard disks don't have all the space occupied with a Physical Volume, will be very easy and online expand any thing of LVM which is desired, as also can be util if you want to use such space free for other things out of LVM.
Moreover, as a administration strategy, if my DRBD resource has a space very limited, the verification of DRBD storages will take less time to complete (talking in hours of time), and when more later i want do grow the DRBD resource for any need (that always i can do it), entails to that after will be need grow the Physical Volume and the Volume Group that is within of the DRBD resource, then finally, i will gain time for that DRBD completes the verification of his storages that are executed automatic and periodically if is that it is limited the space of these resources.
Unfortunately, the times of delay for that finish the tasks of verifications of storages replicated or shared always was a topic of study and strategy important for his administrators, due to that also the VMs are using these same hard disks at the same time that a verification is in progress, and obviously it can be more critical talking in speed terms when a data base depend of these hard drives.
And finally, I know that the all manufacturers of hard drives tell us about of the percent of error in writes that have his hard drives, and is for it (as also for other reasons), that any decent RAID controller have the option of verify these units.
So in conclusion, and talking in general mode, as are needed that the systems to make these tasks:
1) The backup of the VMs.
2) The verification of the storages replicated.
3) The verification of the HDDs.
4) All these tasks must be do in online mode, but none at the same time for avoid degradation of yield.
It is for it that i need reduce the times of this verifications to the max possible, and also so i need to have the data and storages as small as possible, whether they are in a RAID Controller, as in LVM, DRBD, Gluster, Ceph, hardware storage or any kind of storage that exists.
Best regards
Cesar
----- Original Message -----
From: Daniel Hunsaker
To: Cesar Peschiera ; Alexandre DERUMIER ; pve-devel at pve.proxmox.com
Sent: Saturday, November 29, 2014 8:43 AM
Subject: Re: [pve-devel] Error between PVE and LVM
It'll be some time before such options can be added to the underlying Proxmox API.
As to your comments about the resize not showing in the GUI even with qm resize, that isn't quite true. Let's say you'd resize your LV normally using `lvextend -L 100G`. I understand you'd prefer to use `100%` here, but just bear with my example for the moment and pretend you'd use `100G`. Changing that to `qm resize 100G` would not only resize the LV to 100 GB, but also tell QEMU about the new size, which would in turn update the GUI. That's because the qm command hooks into the same code the GUI uses to make the changes it makes. So switching to `qm resize` will give you the VM/GUI update at the cost of using % sizes (for now).
I still don't understand what benefit you'd get from increasing a single VM's LV to the full VG size. No other LV would then be able to grow within that VG. The only setup I can imagine that would avoid that problem is one where each LV has a dedicated VG, which is to say, each VG only has a single LV. That setup seems pretty inefficient to me, not really taking advantage of LVM's design principles. But then, maybe I'm just missing something.
On Sat, Nov 29, 2014, 00:37 Cesar Peschiera <brain at click.com.py> wrote:
Hi Daniel
As the moderns Windows systems have the options of grow or shrink the partitions of his HDDs online, add such features to the PVE GUI will be very pleasant.
And if is possible also add the a option of "resize to the max allowed" (the space available in his Volume group) , will be fantastic.
Best regards
Cesar
----- Original Message -----
From: Daniel Hunsaker
To: Alexandre DERUMIER
Cc: pve-devel at pve.proxmox.com ; Cesar Peschiera
Sent: Friday, November 28, 2014 3:55 AM
Subject: Re: [pve-devel] Error between PVE and LVM
The only difference between lvresize and lvextend is that lvresize supports shrinking the volume as well as growing it. My comments aren't questions so much as observations on a patch series I'm planning to create and submit that will allow shrinking volumes as well as expanding them. Probably roll the max-free option in there as well if it hasn't been added already by then, though I wonder at the utility of such an operation, since you could only use it on one lv per vg.
On Thu, Nov 27, 2014, 23:49 Alexandre DERUMIER <aderumier at odiso.com> wrote:
Sorry, but I'm a bit lost in all the discussion.
are your questions (both daniel and cesar) about shrinking ? or extend ?
(I don't have used lvm since a long time, don't known the difference between lvresize and lvextend).
@cesar, I don't understand why since the begin of this discus, you resize manually the lvm disk.
(If the need is to do it command line, use qm resize, it'll extend the lvm volume and tell to qemu the new size)
----- Mail original -----
De: "Daniel Hunsaker" <danhunsaker at gmail.com>
À: "Alexandre DERUMIER" <aderumier at odiso.com>, "Cesar Peschiera" <brain at click.com.py>
Cc: pve-devel at pve.proxmox.com
Envoyé: Vendredi 28 Novembre 2014 06:32:15
Objet: Re: [pve-devel] Error between PVE and LVM
Ah, good, it does support +size. In that case, simply swapping `lvresize` into the code in place of `lvextend` (along with properly handling -size to convert it to an absolute size for the command) would add shrinking support to LVM storage. Just need to further explore the other storage plugins' resize options to get shrinking for them as well. Makes the patches a bit simpler.
And yes, I always forget about `qm`. It's quite a bit simpler than `pvesh`.
On Thu, Nov 27, 2014, 22:11 Alexandre DERUMIER < aderumier at odiso.com > wrote:
>>But for this moment, i have two questions:
>>1) Do I have any simpler option to grow my LV(that is the HDD of the VM) by
>>CLI?
>>2) If the answer is correct, what exactly should i execute?
all the gui feature are available with cli, with "qm" command.
#qm resize <vmid> <disk> <size>
#man qm
qm resize <vmid> <disk> <size> [OPTIONS]
Extend volume size.
<vmid> integer (1 - N)
The (unique) ID of the VM.
<disk> (ide0 | ide1 | ide2 | ide3 | sata0 | sata1 | sata2 | sata3 |
sata4 | sata5 | scsi0 | scsi1 | scsi10 | scsi11 | scsi12 |
scsi13 | scsi2 | scsi3 | scsi4 | scsi5 | scsi6 | scsi7 | scsi8
| scsi9 | virtio0 | virtio1 | virtio10 | virtio11 | virtio12 |
virtio13 | virtio14 | virtio15 | virtio2 | virtio3 | virtio4 |
virtio5 | virtio6 | virtio7 | virtio8 | virtio9)
The disk you want to resize.
<size> \+?\d+(\.\d+)?[KMGT]?
The new size. With the '+' sign the value is added to the
actual size of the volume and without it, the value is taken
as an absolute one. Shrinking disk size is not supported.
-digest string
Prevent changes if current configuration file has different
SHA1 digest. This can be used to prevent concurrent
modifications.
-skiplock boolean
Ignore locks - only root is allowed to use this option.
----- Mail original -----
De: "Cesar Peschiera" < brain at click.com.py >
À: "Daniel Hunsaker" < danhunsaker at gmail.com >, "Alexandre DERUMIER" < aderumier at odiso.com >
Cc: pve-devel at pve.proxmox.com
Envoyé: Jeudi 27 Novembre 2014 21:01:28
Objet: Re: [pve-devel] Error between PVE and LVM
Thanks Daniel, your words are encouraging for the future of PVE and for me.
But for this moment, i have two questions:
1) Do I have any simpler option to grow my LV(that is the HDD of the VM) by
CLI?
2) If the answer is correct, what exactly should i execute?
Best regards
Cesar
----- Original Message -----
From: Daniel Hunsaker
To: Alexandre DERUMIER ; Cesar Peschiera
Cc: pve-devel at pve.proxmox.com
Sent: Thursday, November 27, 2014 3:37 PM
Subject: Re: [pve-devel] Error between PVE and LVM
If the GUI is resizing volumes, the API supports it, which means you should
be able to use `pvesh` to do the operation in one command, instead of using
the LVM commands and QEMU monitor directly. It does only support specifying
the new size in bytes (which it seems to convert to MiB before actually
using), but it's still an option.
As for the "max available" option, I'd personally find it more useful to
upgrade the API itself support the full range of `lvresize -L` values (it
currently uses `lvextend`, which means volumes cannot be reduced in size - a
fairly safe approach in case the filesystem inside the VM hasn't been
reduced in advance, but also a bit restrictive), or at least the largest
subset we could also support for other storage plugins. I'll see about
implementing that if nobody else gets to it first.
On Thu, Nov 27, 2014, 09:15 Alexandre DERUMIER < aderumier at odiso.com > wrote:
>>This process is correct when you use the GUI, but when you have space
>>limited in the hard disk, and you want to change some partitions by CLI,
>>where finally will be working with the logical volumes, is when starting
>>the
>>problem due that the VM not see the change applied.
ah ok.
This is normal, you need to tell to qemu what is the new size.
(This is what we are doing in the code : vm_mon_cmd($vmid, "block_resize",
device => $deviceid, size => int($size)); )
if you manually upgrade the disk size,
you need to use the monitor :
#block_resize device size
ex:
#block_resize drive-virtio0 sizeinbytes
----- Mail original -----
De: "Cesar Peschiera" < brain at click.com.py >
À: "Alexandre DERUMIER" < aderumier at odiso.com >
Cc: pve-devel at pve.proxmox.com
Envoyé: Jeudi 27 Novembre 2014 17:00:37
Objet: Re: [pve-devel] Error between PVE and LVM
Hi Alexandre
>This value correctly change after resize ?
If, before change, the logical volume had a smaller size.
>We first extend the lvm disk, then we tell to qemu the new disk.
This process is correct when you use the GUI, but when you have space
limited in the hard disk, and you want to change some partitions by CLI,
where finally will be working with the logical volumes, is when starting the
problem due that the VM not see the change applied.
Please let me to do two suggestions:
- Maybe will be better than PVE GUI have a option that say: "resize to max
available", or something.
I guess that this first option would be very good due to that the user will
not need calculate the space available considering the space used in the
metadata of LVM.
- Moreover, in previous versions of PVE, while that I could see the
reflected changes into the VM, in the PVE GUI, when i see the size of his
hard disk, it shows his old size, then i had that remove the disk for re add
it, only of this manner i could see his new size.
>What kind of disk do you use in your guest ? virtio ? scsi ? ide ?
Virtio-block, moreover i have good references about virtio-scsi, do you know
something about virtio-scsi for use it in windows systems?
Many thanks again for your attention
Best regards
Cesar
----- Original Message -----
From: "Alexandre DERUMIER" < aderumier at odiso.com >
To: "Cesar Peschiera" < brain at click.com.py >
Cc: < pve-devel at pve.proxmox.com >
Sent: Thursday, November 27, 2014 6:35 AM
Subject: Re: [pve-devel] Error between PVE and LVM
So,
>>shell# lvs
>>LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
>>vm-100-disk-1 drbdvg2 -wi------ 30.00g
This value correctly change after resize ?
the resize code is here:
we first extend the lvm disk, then we tell to qemu the new disk.
(What kind of disk do you use in your guest ? virtio ? scsi ? ide ?)
/usr/share/perl5/PVE/ QemuServer.pm
sub qemu_block_resize {
my ($vmid, $deviceid, $storecfg, $volid, $size) = @_;
my $running = check_running($vmid);
return if !PVE::Storage::volume_resize($ storecfg, $volid, $size,
$running);
return if !$running;
vm_mon_cmd($vmid, "block_resize", device => $deviceid, size =>
int($size));
}
/usr/share/perl5/PVE/Storage/ LVMPlugin.pm
sub volume_resize {
my ($class, $scfg, $storeid, $volname, $size, $running) = @_;
$size = ($size/1024/1024) . "M";
my $path = $class->path($scfg, $volname);
my $cmd = ['/sbin/lvextend', '-L', $size, $path];
run_command($cmd, errmsg => "error resizing volume '$path'");
return 1;
}
----- Mail original -----
De: "Cesar Peschiera" < brain at click.com.py >
À: "Alexandre DERUMIER" < aderumier at odiso.com >
Cc: pve-devel at pve.proxmox.com
Envoyé: Jeudi 27 Novembre 2014 09:11:29
Objet: Re: [pve-devel] Error between PVE and LVM
Hi Alexandre
Thanks for your attention, here my answers and suggestions about of the
problem of your customer:
>We have made no change since resize feature has been implemented.
>Can you describe a little bit more the problem on the guest side ?
>do you see disk size increase with parted/fdisk ?
I see the new size (vm-100-disk-1) of the logical volume by CLI, but it
isn't reflected into the VM.
In my case DRBD is in a upper layer to the LV, but the concept of LVM is
applicable for any Logical Volume in any kind of block device that Linux can
recognise.
shell# lvs
LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
vm-100-disk-1 drbdvg2 -wi------ 30.00g
data pve -wi-ao--- 143.50g
root pve -wi-ao--- 20.00g
swap pve -wi-ao--- 20.00g
>I have add a customer during a previous training session, which have
>problem with raw lvm disk in vms,
I don't have problems with the VMs (LVM or raw image file), only with the
LVM resize by CLI.
>because of proxmox host scanning all lvm disks on the host side. (Don't
>remember if it's have impact on resize).
It don't have impact on resize, and it is necessary for that LVM can manage
the changes online included (VM and host), that it is my case.
Moreover, for my DRBD resources, i use this filter on the lvm.conf file for
avoid scanning all lvm disks:
filter = [ "r|/dev/sdb1|", "r|/dev/sdc1|", "r|/dev/sdd1|", "r|/dev/sde1|",
"r|/dev/disk/|", "r|/dev/block/|", "a/.*/" ]
Where:
a=accept (include) , and
r=reject (exclude) the scans to speed startup.
>We have need to add a filter in lvm.conf on the host, to exclude scan of
>vms lvm disk.
Sure, i use the CLI
An additional note of IBM:
In the best practices, LVM as block device is the mode more fast for get the
better performance in reads and writes of disks.
Official Web page of IBM in "Best practice: Use block devices for VM
storage":
http://www-01.ibm.com/support/ knowledgecenter/linuxonibm/ liaat/liaatbpblock.htm
And finally, my question:
Can be corrected my problem?
Best regards
Cesar
----- Original Message -----
From: "Alexandre DERUMIER" < aderumier at odiso.com >
To: "Cesar Peschiera" < brain at click.com.py >
Cc: < pve-devel at pve.proxmox.com >
Sent: Thursday, November 27, 2014 3:47 AM
Subject: Re: [pve-devel] Error between PVE and LVM
Hi,
>>In previous versions of PVE, this task was possible do it with much
>>easily.
We have made no change since resize feature has been implemented.
Can you describe a little bit more the problem on the guest side ?
do you see disk size increase with parted/fdisk ?
Do you use raw lvm disk in your vms ? or partitions on top of lvm ?
I have the LVM partition, and the image of the virtual disk isn't on a file
system (as raw, qcow2, or any other kind of file format), so my image disk
is a LVM as block device.
I have add a customer during a previous training session, which have problem
with raw lvm disk in vms,
because of proxmox host scanning all lvm disks on the host side. (Don't
remember if it's have impact on resize).
We have need to add a filter in lvm.conf on the host, to exclude scan of vms
lvm disk.
----- Mail original -----
De: "Cesar Peschiera" < brain at click.com.py >
À: pve-devel at pve.proxmox.com
Envoyé: Jeudi 27 Novembre 2014 07:15:19
Objet: [pve-devel] Error between PVE and LVM
Hi to the PVE team.
I found a problem between PVE and LVM.
Considering that if it is used LVM as block device for the virtual disks of
the VMs, Linux give us a great comfort, but the problem is that if I in
"online mode" enlarge a Physical Volume and after enlarge a Logical Volume
by CLI, in PVE, the VM can not see the new free hard disk space without
partition.
In previous versions of PVE, this task was possible do it with much easily.
Moreover, i think that this feature is very util, due to that in the actual
condition, it force me to power off the VM and start it again, so that being
a server (talking about of the VM) that is in a production environment, only
can I do it outside of working hours.
So i would like to ask if the PVE team have interest in correcting this
problem.
Best regards
Cesar
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