How to use more local storage?

[rengiared]

hi

i'm using PVE now since about 2 months on 8 blades with about 18 VMs and i'm really glad i got it recommended

Now i wish to use PVE on a DELL R710 where i have two raids, one raid1 and one raid5
Initially i tried to install it on an integrated SD-Modul with a 16GB SD-Card but GRUB has a small problem with it, but thats not my problem at the moment.

Now i installed it on the RAID1 but i don't know how to embed the RAID5 right.
I followed this guide http://pve.proxmox.com/wiki/Storage_Model#LVM_Groups_with_Local_Backing but than i have the problem i can't use qcows and if possible i would like to use them.
Unfortunately i'm a total linux noob and just don't get it atm.

maybe someone could help me out
thanks in advance

 

[JustaGuy]

i can't use qcows and if possible i would like to use them.

I'm not sure about the idiosyncrasies of the qcow format or why you wouldn't be able to use that on your local storage.
LVM storage is the higher throughput method as opposed to a directory storage.
I think you can simply dd to & from LVM, but I haven't had to yet so I'm not sure.

Here are a couple links from a quick forum search that might start you in the right direction:
http://forum.proxmox.com/threads/4528-where-are-the-vm-files?highlight=where+vm+files
where are the vm files?


qcow2 auto resize?


All I know about qcow is that you can choose to create that kind of disk from the web interface when you're adding storage to a VM. I've never used it since from what I read here the raw format on LVM outperforms other modes.

Maybe I'm not clear on what your immediate task is, are you trying to migrate existing qcow to use with a VM?
The web interface can make disks in qcow if thats what you mean.

In the hardware tab of the VM under the 'add disk' submenu there's a drop-down entry to choose the image format of raw, vmdk or qcow.

I've used a Clonezilla LiveCD inside the VMs before I knew how to move disks around.

Here are some posts that may be of use to you as well, at least to get a better understanding of working with disks.

Need help on moving disk image from one KVM machine to another


Extending VM Hard Drives


http://forum.proxmox.com/threads/2609-Need-help-on-moving-disk-image-from-one-KVM-machine-to-another
I guess it would help if you mentioned how what you're trying isn't working.

 

[rengiared]

i think you got me wrong
i just want to use qcows cause they have the ability to grow, and unfortunately raw's can't grow automatically.
so if i have a guest with windows XY on it, i create a qcow with max. size of 100gb, but at the start it only has a few gb and not the full 100gb on the host.
raw files start with the max. size and thats why i would prefer qcows.

and the reason why i can't use qcows at the moment is because its not possible. here is a quote out of my linked wiki entry

Image format: raw (that is the only option you can choose now)

and i can confirm that, its not possible to choose another option if i want to store a disk on the second local storage (only RAW is possible) (and yes i tried it on the web interface)
and of course, thats my problem at the moment and if its possible in some way i would like to continue using qcows instead of raws

 

[JustaGuy]

unfortunately raw's can't grow automatically.
so if i have a guest with windows XY on it, i create a qcow with max. size of 100gb, but at the start it only has a few gb and not the full 100gb on the host.
raw files start with the max. size and thats why i would prefer qcows.

Ok, I see. I didn't know of that limitation with LVM storage. Seems a directory storage would be necessary instead.
The raw files are sparse, so they do have expansion characteristics:

if you run a file system with support of sparse files (like ext3) the space is NOT pre-allocated when you use "raw". so its basically no difference to qcow2 (in term of wasting space). there are other differences.

see http://en.wikipedia.org/wiki/Sparse_file

if you use block devices directly (LVM2, DRBD, ...) always the whole space is allocated (always raw) - behavior by design.

I see the size & speed of my backups correlate to the amount of actual data usage on the disk, rather than its capacity.

 

[rengiared]

ah, ok, thanks
as i said i'm completely new to the whole linux world so sometime its hard for me
in the meantime i think i found a partial solution in another thread: http://forum.proxmox.com/threads/5000-trying-to-install-proxmox-with-raid?p=28764#post28764

You can create a logical volume on your xxl (lvcreate -n openvz -L 100G xxl), create a filesystem on it (mkfs.ext3 /dev/xxl/openvz)

i think with this and a little bit more i'm going to solve my problem

If you have further information please do not hesitate to tell me

 

[JustaGuy]

If you have further information please do not hesitate to tell me

What comes to mind are the mistakes I made when I was early in this, ie. Once I used symlinks & later found I had caused some unnecessary complication.

You seem to have found a better way already.

Have fun.

 

[rengiared]

now i'm stuck at the moment where i add the storage in the web interface
i have done this so far:

pvcreate /dev/sdb
vgcreate raid5 /dev/sdb
lvcreate -n lvm -L 380g raid5
mkfs.ext3 /dev/raid5/lvm

fdisk -l reports me:

Disk /dev/dm-3: 375.8 GB, 375809638400 bytes
255 heads, 63 sectors/track, 45689 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000


but how can i add the directory storage now?
if i try it with /dev/dm-3 in the web interface i get this error:

Error: mkdir /dev/dm-3: File exists at /usr/share/perl5/PVE/Storage.pm line 2129

Please have pity on me
tia

 

[dietmar]

but how can i add the directory storage now?

You need to mount /dev/raid5/lvm somewhere:

# mount /dev/raid5/lvm /your/mount/point

and maybe add it to /etc/fstab

 

[jinjer]

I don't get it ... what is the problem with extending the LV created by the interface "by hand" ? You'll need that the system on top to be able to grow the disk (perhaps dynamic volumes in windows) ... but the expansion of the LV would be the easiest part.

jinjer

 

[rengiared]

thanks dietmar, that was the missing point
(sorry for the late response, i had to wait for the new 8gb DOM)
as described in this thread: http://forum.proxmox.com/threads/5069-min.-System-Requirements-for-Harddisk