|
 |
|
General Information
|
Add To My Personal Library |
May 8, 2009
• Vol.31 Issue 14
Page(s) 30 in print issue
|
Perform Backups Of Virtual Servers
Plan Ahead & Take New Methods Into Consideration
|
| Key Points
Virtual backup methods don’t differ a great deal from physical methods. But you’ll still need to educate yourself to determine what is the best backup method for your enterprise. You’ll also want to shop around; don’t assume your physical backup vendor’s pricing will apply to virtual backup services. | | All too often, enterprises that bring virtual servers into their data centers don’t have plans in place for backing up the information on those servers. But any move to virtual servers must be accompanied by a method for how, and how often, to perform backups.
Too often, this vital component of virtualization is overlooked, explains Alex Weeks, vice president of professional services at Kovarus, an IT consulting firm. Without a backup plan, Weeks says that an enterprise likely will not fully realize the kinds of savings it could see with virtualization.
“Let’s face it, system backup is the thing everybody has to do only because they have to do it,” he says.
It goes without saying, however, that if your enterprise were ever to lose information or need data restored, a backup would be vital.
 Methods
Although the backup processes won’t change much as you move to an environment with virtual servers, experts say you will have to take new methods into consideration.
Brace Rennels, certified business continuity professional at Double-Take Software, says the underlying technology to back those virtual workloads still mirrors physical backup methods. He breaks down the methods into hardware-based and host-based replication.
Hardware-based methods rely on a SAN, which attaches to the virtual servers and replicates the virtual disk images offsite to another storage device. This process offers either synchronous replication or a snapshot-type technology.
As the name implies, synchronous hardware-based technology replicates information more quickly. Because it sends information in blocks rather than bytes, it usually faces distance limitations and requires more bandwidth than snapshot-type technology, Rennels explains.
The snapshot process periodically sends updates at scheduled intervals to the virtual disk image at the backup site. Rennels says this process is only available between like devices.
If you’re not using the snapshot process, make sure you aren’t locked into a hardware-specific backup application that can only communicate with devices like itself, he adds.
Host-based replication technology sits on the virtual server and replicates changes to the virtual disks as they occur. It then applies them to the target servers in the order of the operation they are received. This method consumes less bandwidth than hardware-based methods.
Whatever method you choose, you’ll likely still rely on tape. When the virtual disk images have been replicated to a designated backup, Rennels explains that tape is often used to archive those disk images.
This would be a good time to review your overall backup plan, he adds. If you already have a disaster recovery solution in place, Rennels suggests making sure it’s flexible enough to encompass physical and virtual server platforms.
Longer Backup Times
Though the physical backup method may be the same, IT managers need to be aware of the differences between backing up virtual servers and physical servers. The key is to have a backup plan established before the first virtual server is installed.
Traditional backup approaches don’t scale well in a virtualized environment.
Let’s say your enterprise runs on a standalone physical server that is virtualized with 10 to 20 others. Weeks says, “To try to run all your backups on that one piece of hardware as though they’re all physical servers, you’re compounding your problem.”
Weeks recommends that you consider consolidating backup technology, which lets you do away with having to install backup software on each server, whether it is virtual or not.
“You can set up one system that has the capability to perform all of your backups of all machines,” Weeks says. “So you’re not using multiple backup agents on one physical piece of hardware.”
Art Powell, COO at Trinsic Technologies (www.trinsictech.com), says traditional backup solutions can be expensive because their pricing structures reflect the need to back up many servers, virtual or not. Some vendors are better about fairly pricing virtual backup services than others. Be aware of your vendor’s pricing for virtual backup.
You may also need to change your enterprise’s entire backup strategy. For instance, your backups may need to run at a different time than in the past, Powell explains.
He says that when some of his clients have tried to carry over their existing physical backup technologies to the virtual servers, they met with very long backup windows—from 12 to 18 hours by dint of the sheer volume of data they’re backing up.
"Those backup methods can be very resource-intensive and tax servers, processors, and RAM. [They also] can consume network and storage bandwidth,” says Powell.
“The weakness of virtual farms is the disk I/O performance. If you have five to 10 servers on a machine and six are hit with heavy use and the rest are backing up, you’ll get hit heavy with slowdowns,” Powell says. “If you have people who want to work on the server at night, then you can’t run backups at night.”
As you’re looking at these things, Rennels suggests you also review your WAN infrastructure. Some types of backup hardware require more bandwidth than others and can have distance limitations. Others can also saturate existing bandwidth during the transfer process. WAN accelerators can improve bandwidth limitations, he says.
Age-Old Advice
Even though you may be embarking into the brave new world of virtualization, do not forget basic backup principles, says Robert Bloomquist, senior engineer for virtual recovery at Kroll Ontrack, a software services and consulting company. With the growth of virtualization, Bloomquist says his company has seen an attendant spike in the number of virtual recovery requests due to physical or operating system failure during configuration or system maintenance.
Bloomquist explains that the single most important detail to avoiding these scenarios and making sure data is secure and protected is to test your backups. He says, “We’re amazed by how many companies still don’t follow the basic rules of backup 101: testing backups regularly to ensure you can restore from them.” 
by Jean Thilmany
Top Tips
• Have a plan for backing up information in place before you install your first virtual server.
• Although backup methods between physical and virtual servers don't differ much, expect other aspects, such as backup times, to change.
• Choose a backup method that’s right for your enterprise and your servers.
• Backing up virtual servers will likely take longer than running your physical backups. Plan accordingly when considering your options for shaving backup time.
• Consider a WAN accelerator, which can improve bandwidth limitations. |
|
|
