A Washington state public utility turns to STORserver to back up virtual machines. Snohomish PUD No. 1 uses HP ProLiant blade servers and VMware ESX Server virtualization software to conserve power and reduce data center growth, while STORserver Agent for VCB solves VM backup problems.
The utility company for Snohomish County District 1, Snohomish
PUD No. 1, knows the value of power since it supplies electricity for 300,000
residences and businesses, including Boeing.
But just because the utility produces electricity doesn't mean
it gets the power for free, so Snohomish PUD No. 1 found itself in the same
situation as many other organizations-wanting to conserve power and reduce data
center growth.
Also like many organizations, it decided that virtualization
would help address those issues, reducing the number of physical servers employed
by having each one host a large number of virtual servers running concurrently
and independently of one another.
Since late 2007, Snohomish PUD No. 1 has purchased 28 ProLiant
460 and 480 blade servers from
Hewlett-Packard, installed
VMware's ESX Server
virtualization software, and reduced the number of traditional physical servers
and server racks.
Melinda Cooper, senior infrastructure system analyst and
domain administrator for Snohomish PUD No. 1, noted that instead of buying 30
new servers over the past year, the utility is now running 30 virtual machines
on four ESX Server-based systems.
Cooper's organization is responsible for providing services to
internal customers, including the creation of development and testing
environments for in-house staff. The servers also run applications such as "cashiering,
keycard access, payroll, PeopleSoft [enterprise resource planning], [Microsoft]
Exchange and many SQL databases," Cooper told eWEEK.
Clearly, these kinds of mission-critical data and applications
need to be backed up frequently, but unless managed carefully, that process can
eat up an inordinate amount of time and resources. Cooper has implemented a
virtual storage backup system that conserves that time and energy in proportion
to the energy and cost savings of virtualizing physical servers.
Technological trade-offs
There are several approaches to backing up VMs, and each of
them involves a trade-off in terms of complexity and reliability.
One approach is to install a backup agent as if the VM were a
physical machine. Snohomish PUD No. 1 was using
IBM's
Tivoli Storage Manager and began using the application to back up virtualized
servers. However, this presented a number of problems.
Administrators have to use a command-line interface to
configure TSM, which is not a trivial
exercise, Cooper said. Moreover, TSM makes
only file-level backups, while Cooper also wanted full-machine backups.
Another drawback to this approach is that when there are a number
of VMs on a single ESX Server host, administrators have to perform the
laborious chore of scheduling backups to ensure that the VMs don't compete for resources
during the backup period, slowing overall system performance.
Moreover, machines have to be shut down prior to the backup
because if the VMs are working when the backup is under way there's a chance
that transactions will be missed. Alternatively, administrators can take a
snapshot of the machine's VMDK (Virtual Machine Disk Format) file, which
represents the whole VM as a single file. In either case, manual scripting of
pre- and post-backup processing is required.
While a full-machine snapshot provides for fast restoration of
the VMDK files-and thus quick recovery of the entire VM-it doesn't allow
individual files or folders to be restored.
This means, "You don't get the configuration files, so if
a [virtual] server is damaged, you can't restore that," Cooper told eWEEK.
And unless the admin specifically adds backup of the configuration files to the
full machine backup of the VMDK files, he or she won't be able to restore the
virtual server if it is damaged.
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