Setting up NSF server for ESXi4

[wobbe]

Hello all,

I'm thinking about setting up an old proliant DL380G2 as a NSF storage to use with VMWare ESXi4. I would like to use LVM to make snapshots of the running VMware guests and use Backup Exec to copy the data to tape. I've done a quick test with openfiler and was able to restore a working copy of linux.
But I have no experience with LVM snapshot so I'm a bit worried about doing this with a running guest. To me snapshotting a running guest looks a bit like yanking out the power cable. Are there any chances the data in the snapshot won't be consistent and I would not be able to recover and boot the guest?

Regards,

WB

[Joseph L. Casale]

A few things from experience to take note of:

1. If you snap a running vm, its in a crash consistent state, this means the backup you have _is_ exactly like the pulling the power cord out of a running physical server and imaging immediately after.

2. ESX's nfs performance can be very low if not setup right, as esx only uses sync io in its nfs client IIRC, so you may want a battery backed hardware raid controller in front of your discs for example to allow nfs to continue processing rw's while it _safely_ flushes data. There are also scheduler tweaks that may yield better performance but as I gather you are using OF, I assume they have set applicably but I don't know. So far the default scheduler in RHEL/CentOS isn't the best for this scenario.

[wobbe]

Thanks Ritmo2k for you insights.

So I guess there is a chance that the snapshot won't work. But how big is that change? It would probably depend on the kind of operations that take place within the guest at the time of the snapshot.
All the big storage comagnies do snapshots, how do they make sure that they get consistent backups?

I'm planning on using CentOS because this will probably run on Proliant Hardware and I should be able to install the HP agents for hardware monitoring. Open filer in based on rPath and since my linux knowledge is limited I don't want to add a new player to my daily battlefield.
So what is this default scheduler you are taking about, could you explain that a little further?

[Joseph L. Casale]

They write drivers that interact with the OS like vmware for example and quiesce the os and applications like using ms vss for example.

http://www.mail-archive.com/centos@centos.org/msg41856.html

http://www.mail-archive.com/centos@centos.org/msg19536.html

Good luck!
jlc