Hello Andrey,
I read Citrix XenServer and NetApp Storage Best Practices (http://media.netapp.com/documents/tr-3732.pdf) and I found a nice explanation on SnapShot:
SNAPSHOT FOR VIRTUAL MACHINES ON NETAPP DATA ONTAP AND NFS STORAGE REPOSITORIES
Creating VM snapshots for those VMs whose VDIs are resident on the NetApp Data ONTAP SR utilizes the NetApp device Snapshot technology directly by invoking the Snapshot at the device level. This results in minimal resource usage on the XenServer host in terms of CPU and memory during the snapshot process.
The snapshot process for VMs using the standard NFS, iSCSI, and Hardware HBA SRs, however, do not invoke any NetApp device capability. It uses the VHD capability for its VDIs to allow chaining for the original and snapshot VDI to share common data. The original VDI proceeds to make its own changes in an isolated copy-on-write version, with the snapshot VDI being Read Only.
XenServer 5 provides a convenient snapshot mechanism that can take a snapshot of a VM's storage and metadata at a given time. Where necessary, IO is temporarily halted while the snapshot is being taken to ensure that a self consistent disk image can be captured. Snapshot operations result in a snapshot VM that is similar to a template. The VM snapshot contains all the storage information and VM configuration, including attached VIFs, allowing them to be exported and restored for backup purposes.
However, before I could test this - I ran into a problem with a seemingly easy NFS SR setup described on pages 42-47.
I followed all the instructions but when I try to attach the NFS export (share) that I created on NetApp side (step 10), after I enter it's path 10.10.10.10:/vol/XenServer_NFS_Storage and hit Finish button - I get an error saying "The storage repository is not available. Check settings and try again." I tried some vatiations but the result is the same.
Do you have some experience with connecting NFS SR on NetApp with XenServer?
Thanks,
Igor
