Disk-based backup has taken a huge step forward in recent years
with the advent of the
virtual tape library (VTL), but the
technology may already be on its way out, according to some
users and analysts.
"In the short term, the need to emulate tape is important,"
according to Jeff Machols, systems integration manager at benefits
provider CitiStreet, a subsidiary of Citigroup and State Street
Corp. "Long term, I see the need to emulate tape diminishing; the
actual emulation of tape and robotic libraries was merely a way to
get in the door for the VTL."
The appeal of virtual tape libraries, Machols said, is that
companies can add disk to their backup process without having to
change their backup software, scripts or procedures, all of which
were originally designed to write to tape. Now that
disk-based backup is becoming widely
accepted, "the software companies are the ones [that will] be
running to catch up," he said. "Organizations are going to want
to start taking advantage of more and more disk-to-disk
functionality and will probably be willing to switch software if
one product has a richer feature set supporting disk-based
systems."
Machols said he's striving to eliminate tape from his environment
entirely, citing the falling price of disk, the rise of
disk-platter capacities and his belief that disk is better for
archiving purposes. "Storing critical [or compliance] data on tape
long term is not a wise solution," he added. "Tapes can be
unreliable, and it can be difficult to recover very old tapes."
For that very reason, Machols said his company has gone with a
VTL from Sepaton Inc., which doesn't write to tape at all. For
off-site data protection, the Sepaton VTL allows replication to an
identical VTL box in another location, he said.
Mark Stewart, backup administrator at Randolph Air Force Base in
Texas, agreed with Machols that long-term archiving on tape can be
a pain. "One must migrate data from media format to [media] format
as hardware upgrades occur," Stewart said. Generally speaking,
there will probably always be users who stick with tape; therefore,
there will always be backup software companies that gear products
toward writing to it. And as long as that happens, VTLs, as we know
them, will have a role to play.
But the virtual tape libraries on the market today are in for
many changes, according to W. Curtis Preston, vice president of
data protection services at GlassHouse Technologies Inc.,
Framingham, Mass.
"Any company that only offers VTL without any other
functionality, like deduplication, will cease to exist within a
year or two," he said. "But the VTL companies we have now, like the
Sepatons, FalconStors [Software Inc.] and Diligents [Technologies
Corp.] of the world, will continue to evolve and exist."
The emulation of tape, according to Preston, is just one way the
disk-based backup platform can communicate with the backup
application and represent "the backup as files that make sense to
the backup application."
"Basically, you have this
tarball sent out by the backup application,
with files in its own proprietary format … What new backup
targets will be able to do is reorganize the data so that it can
be easily accessed for restores and put it into a format that
can be read by other applications."
According to Preston, several vendors are already working on new
disk-centric forms of "intelligent backup targets." Diligent and
Sepaton have plans in the works for presenting backups as a
reconstituted organized file system, he said, with announcements
beginning later this year. Diligent and Sepaton declined to
comment.
This new class of intelligent backup targets could have a
profound effect on the day-to-day life of backup administrators.
"In the future, users may be able to use a Web interface to drag
and drop from the backup target to do recoveries themselves,"
Preston said.