By Dave Simpson
-- Sanbolic, which specializes in clustered file system software for shared-storage SANs, recently introduced a version of its Melio 2010 Data Center suite with improvements for Citrix virtual server environments, particularly in the areas of provisioning, scalability, high availability and data protection.
For example, Melio 2010 Data Center provides high availability for Citrix Provisioning Server (PVS), which prevents downtime of virtual machines (VMs) hosting virtual desktops and servers, and increases scalability, according to Momchil Michailov, Sanbolic's CEO. (Dynamic provisioning is a feature in the Platinum editions of XenServer and XenApp, as well as the Enterprise and Platinum editions of XenDesktop.)
Sanbolic's software allows physical or virtual Provisioning Servers to share concurrent block-level access to SAN storage containing PVS datastores, avoiding the locking contention issues incurred by CIFS and NFS. Because the Provisioning Servers access the same virtual workloads on a Melio volume, devices hosting virtual desktops or XenApp Servers can failover between Provisioning Servers, which minimizes downtime, according to Michailov.
"PVS has limited scalability," says Michailov. "Melio allows you to have multiple provisioning servers looking at the same shared storage infrastructure that's hosting your virtual images, thus increasing the scalability of PVS and reducing capacity requirements. We can provision a centralized storage farm that contains all of the VHDs."
"Clustered file systems provide much higher availability, and save administrators a lot of time in the event of a node failure," says Noemi Greyzdorf, a research manager with IDC. "You can be back up and running in a couple minutes or seconds, compared to an hour or more."
In addition, Melio 2010 Data Center – via the AppCluster component of the suite – enables clustering of SQL Server databases to provide high availability for the PVS database in the event of a failure of the initial server hosting the database.
The software also includes distributed VSS-based snapshots and policy-based snapshot migration for backing up shared volumes with PVS datastores and offering data protection for VHDs and device write caches.