[pve-devel] Error between PVE and LVM

[Daniel Hunsaker]

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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