Combining Tape and Disk for
Data Recovery Best Practices
WAN is time-consuming and expensive.
With tape, sites that have a great deal of
data to restore can move that data more
quickly, even if it requires overnight transport to a failed data center.
By MOLLY RECTOR & BETH WALKER
One of the keys to any data recovery planning and implementation is electing the right tools to recover the data. Once the key people, data, and plan have been identified, the right combination of hardware
equipment is required. In virtually every
situation, it makes sense to include tape as
part of your equipment selection.
This may not be consistent with conventional wisdom for data recovery, but
it’s true nonetheless. The disk
industry took the lead in data
protection following poor tape
performance in the 1990s. The
old perceptions about tape have
lingered, but the fact is that tape
reliability has improved more
than 700 percent over the last
10 years and is now quantifiably
more reliable and faster than the
SATA disks that are typically
paired with tape. This speaks to
a significant point: just as disk has a key
role in data protection and disaster recovery, so does tape.
of storage. The short-term use of disk in
the data protection schema is a significant advantage.
Analyst studies indicate that 95 percent of data recovery occurs in the first
two weeks following data creation,
making disk the ideal short-term storage
medium. However, disk is much more
costly than tape, so tape is typically a
better choice for longer-term storage. Just
as shorter-term storage plays to disk’s
strengths, longer-term storage plays to
tape’s strengths.
For sites that manage data carefully,
deduplication and remote replication to
disk have some advantages, primarily
through the ability of the site to restore
the most recent data. Note, however, that
for large quantities of data or sites affected
by power blackouts, this advantage disappears. Copying terabytes of data over a
Data Source: Yasin, Rudy. “The Means to go Green,” Government Computing News GCN
Best Use of Disk
in Data Recovery
SATA disks’ two strengths in terms
of data backup and recovery are random
access of information so that specific
files can be rapidly restored and a familiar interface that allows users to access
files without requiring proprietary software to read the data. Disk is hands-down the best choice in tiering data,
especially using SATA for the second tier
A Little History
Tape had some rough years, and this is
an undeniable fact. During that time, disk
started assuming an important role in data
protection. In most data centers, disk has
been used as a step in the back-up and
recovery process so that data moves from
primary disk (such as Fibre Channel disk)
to secondary disk (typically SATA) then to
tape – disk-to-disk-to-tape (d2d2t). This
was made possible in part because SATA
disk is more affordable than Fibre Channel
disk and much more so than solid state disk.
Because SATA precedes tape in typical data
protection tiering, SATA disk is considered
roughly equivalent to the tape tier and used
when comparing the technologies.
Meet the New Tape
In spite of a common perception of
disk as extremely reliable, SATA disk is,
Tape is also faster than
SATA at moving a lot of data
— and obviously this is important in getting an organization
running again after a disaster.
When comparing throughput,
Tape is the most cost-effective storage
option for data that can tolerate access
times of a few minutes. This is particularly
significant when administrators consider
the amount of disk that is used appropriately. (See above graphic.)
