The newest release of VMware, announced this week, includes a
data migration capability that users have wanted for years, one
that analysts say should prompt storage vendors to change the way
they approach
server virtualization.
The Storage VMotion feature in the next revision of the VMware
Infrastructure due later this year will let users migrate data
associated with virtual machines on shared storage systems the same
way that VMware's VMotion allows the migration of servers.
Users began emphasizing the need for a storage version of
VMotion as early as last May's Storage Decisions conference in
Chicago, where several attendees said that having to
reboot virtual machines when migrating data
between arrays caused frustrating downtime.
Storage VMotion users will be able to run an internal VMware
utility during storage array refreshes or for load balancing on
existing arrays. The utility sprang out of a script briefly
provided to users when VMware introduced VMware Infrastructure 3
(VI3) in its last major refresh in June. VI3 required the migration
of data from the old version of VMware's file system to a newer
one.
Storage VMotion requires the use of a command-line interface
(CLI) to initiate data migration jobs in the first release,
according to Jon Bock, senior manager of product marketing for
VMware. After users enter the data to be migrated, its location and
destination through the CLI, the migration job can be tracked
through VMware's GUI, Virtual Center, according to Bock.
"It was a matter of prioritizing time to market on certain
features as part of a much larger major release," Bock said of the
decision not to integrate Storage VMotion with Virtual Center.
"Users indicated that even a command-line version would solve
enough problems for them that they'd rather not wait."
In certain cases, this new capability in VMware has users
rethinking the purchase of storage virtualization products, which,
until this release, had been the only alternative for migrating
virtual machine data without disruption.
"I try to avoid storage virtualization appliances if I can,"
said Tom Becchetti, senior storage engineer for a medical
manufacturing company he asked not be named. "Adding another device
to my environment goes away from my principle of keeping things as
simple as possible." However, Becchetti said he had been
considering deploying a virtual appliance solely to move virtual
machines between storage subsystems. "It was that much of a
hassle," he said. Now, he said, he's relieved to have to avoid
opening that can of worms altogether.
Evaluating other storage virtualization products
However, other users said they will still evaluate storage
virtualization products for the problems they can address beyond
VMware. For example, one Storage VMotion beta tester said his
company is still evaluating Hewlett-Packard Co.'s (HP) XP24000
virtual array and IBM's SAN Volume Controller (SVC) for simplifying
storage management.
"It would be nice to have something like the XP [array]
aggregate and manage all our storage, from both physical and
virtual servers, as one pool [which Storage VMotion won't do],"
said Jason Lochhead, principal architect for managed hosting
provider Terremark Worldwide Inc.
Storage VMotion also does not address a mix of data from
physical and virtual environments, Lochhead pointed out. Users will
still need a separate tool to migrate any data not associated with
VMware's VMFS file system, which also includes data VMware uses on
"raw" block-access devices.
Data migration is still the leading consideration reported by
users who buy storage virtualization products, according to recent
research from both the Taneja Group and TheInfoPro. Still, other
analysts pointed out that hosts won't have the horsepower to do
wholesale migrations from one array to another in large
environments.
"VMware isn't going to deal with the universe," said Tony Asaro,
senior analyst with the Enterprise Strategy Group. Big shops are
also more likely than smaller ones to have servers that don't run
on the x86 platform, which is currently the only type VMware
supports.
Despite the limitations of Storage VMotion, VMware's influence
has been creeping into the storage world, according to the Taneja
Group's Arun Taneja. "Storage VMotion doesn't do everything storage
virtualization devices can do, such as allowing two storage devices
to look like one," he said. "But this needs to be a warning shot to
the storage industry. The boundaries are shifting. There's going to
be a major transformation in the way servers and storage work
together over the next two to three years."
"If I were IBM or Hitachi, I'd figure out how best to integrate
my product with Storage VMotion," Asaro said, suggesting the
"horsepower" issue for large-scale migrations is the likeliest
place for storage virtualization devices to get in on Storage
VMotion. "You need that big engine for tons and tons of data."
Large-scale data migration
VMware's Bock confirmed that integration with storage
virtualization devices for large-scale data migration is being
considered as part of the recently announced Storage Virtualization
Certification program. "We are talking about how to better leverage
[storage system] tools, even existing block copy tools," he said.
"Using Storage VMotion to migrate metadata and storage
virtualization tools to migrate the bulk of the data in the
background, it's definitely a conversation we've had."
According to Bock, another project being considered by VMware
and its partners in replication and storage virtualization is
VMotion over geographic distances. Users are beginning to clamor
for it also. "We do have a number of customers requesting it," Bock
said. "We want to understand what the actual needs are and which
features are best to implement within VMware or on the storage
side."