smaller root volume or a big one without a data partition

[arthurhugo]

A fresh installation of Proxmox VE 1.0 defaults to a root volume of almost 70 GB (700 mb used). This is way to large and because it's a SAS RAID setup, the harddisk space is expensive.
According to this thread:
http://www.proxmox.com/forum/showthread.php?p=3882
you shouldn't make the root volume too small because vzdump might require the free space. Dietmar suggests not making the root volume smaller than 20gb. Why is that?
From the OpenVZ wiki: "Note that using LVM2 and vzdump to create snapshots requires 512Mb of free space in your VG as described here."
And from what I understand you don't need as much temporary space as is required for the whole container you're dumping.
I won't put the dumps themselves on the root volume.
So could it be that as a minimum 700+512mb whould suffice for the root volume? In that case I was thinking of using 4gb just to be on the safe side (reinstall with # linux maxroot=4 swapsize=4).

Is it also possible to make one large root volume without a seperate data volume? The only disadvantage to this I see is an increased chance the root filesystem will get corrupted and won't boot anymore. This doesn't mather because the system is useless without the data partition and I have to go to the datacenter to fix it anyway.

 

[arthurhugo]

I see now that vzdump Creates a temporary image in /var/tmp.
Can I symlink /var/tmp to a directory on the data volume and still have a very small root volume?

 

[dietmar]

vzdump needs:

1.) 1GB free space in the volume group
2.) you cannot dump a snapshot into the same logical volume (infinite loop). Thats why root and data are separate volumes.

Anyway, make you root partition as small as you want - but dont blame me if you run out of space.

- Dietmar

 

[arthurhugo]

Now that I understand the way LVM2 snapshots work, I went for the small root partition.

Currently, you can only shrink ext3 filesystems when they are not mounted. This means you can't shrink your root volume without booting from a cd-rom or another linux installation.

I won't have to shrink my small root volume but I can unmount the seperate data and backup volumes I created and resize them without having to boot from cdrom.

Not recommeded if you want to manage everything from the webinterface!