As every storage vendor on the planet is always keen to remind you, businesses create more and more data every...
year. Indeed, business now creates so much data that the chore of ensuring it is all available for users and then archived for posterity or legal inspection is universally agreed to be a pain in the proverbial.
Of late, the preferred strategy for dealing with all this data has therefore been to store it on disk, a medium whose falling costs, rising capacity and improving reliability mean it is now advanced as appropriate for even long-term archival applications. Throw in the fact that many organisations have an old NAS or SAN lying around that can be incorporated into tiered storage schemes means disk seems a more sensible archival medium every day.
The downside of disk is the complications caused by its requirement for complex and costly associated networks when used at scale. Disk also has the annoying habits of continually consuming electricity or experiencing catastrophic physical failure.
These frailties mean that despite innumerable predictions of its demise, tape remains a more-than-viable archival medium. Tape, after all, can protect data for years without ever requiring a single electron to light up a wire. And later this year, tape will leap forward to a new generation of technology that will make it faster and vaster than some disk systems.
The technology concerned is “LTO 5” (Linear Tape Open) the 5th generation of a tape format jointly developed by HP, IBM and Quantum. LTO 5 tapes (also known as “Ultrium”) will have a capacity of up to 3.2 terabytes and will be capable of achieving data transfer speeds of up to 360 megabits per second. Both of those statistics challenge and even exceed disk!
LTO 5 is expected to be signed off by the end of 2009 and licensees of the standard will then start to produce tapes and devices capable of playing them.
LTO 5 has impressive specifications that, prima facie, boost tape’s credentials as a storage medium for the future.
But John Derrett, Storage Product Manager of IBM Australia New Zealand’s Systems and Technology Group, believes it could be too futuristic.
“If you buy a new, fast LTO 5 drive and get so many megabits per second, you will need to ask if you will overload a SAN and if the adapter on the server can cope,” Derrett says. “If not, the drive will slow and your backup window will not shrink.”
“So it is not an insignificant task to think through whether you are ready for LTO 5.”
The LTO consortium’s counter to this argument is that it is possible for LTO 5 to have been even faster, but the standard has been throttled back to ensure bottlenecks like those Derrett describes don’t become an issue.
SearchStorage ANZ spoke with IBM’s Bruce Master and Quantum’s Tom Hammond, the companies’ representatives on the LTO consortium, and the pair said that “back in generation three of LTO, we looked at the roadmap which at that time had the performance for each generation doubling .”
“We had a lot of input from customers, OEMs and analysts that many customers were not able to push the drive to its full rated performance. Some customers with very fast disk and SANS could take advantage of it, but most could not, so we reduced the growth from doubling speed in each generation to a 50% increase.”
Nonetheless, IBM’s Derrett believes that businesses need to start thinking about how to take advantage of LTO 5 now, and need to ensure their ponderings go “all the way to the application.”
“Business needs to think about what to change,” he advises. “It could be [backup] procedure or the software they use.”
“If you use fairly simplistic software you may need new software with drivers for LTO5.”
“But you might also need to look at your network because if you suddenly put in LT05 and have more data, can the switches cope? The faithful switch you have hand for years might need a bit of an upgrade!”
Derrett also believes that would-be LTO 5 users will need to think hard about how they back up before they move to LTO 5, lest the extra capacity be wasted.
“In order to get to benefits of the increased speed and capacity you need to look at your backup processes because using 10% of a three-terabyte tape will not mean a great benefit. You might be better off staying with an older technology because if you just cut across to the new [Ultrium] cartridges and put a small amount of data on it you will end up with a small benefit.”
Chris Holloway, Chief Technology Officer at Spectrum Data, also says LTO 5 may struggle to find users.
“LTO 5 does have capacity advantage,” he says. “But in terms of client readiness, they are holding steadfast with current technology. Existing customers using LTO 3 or 4 are quite happy.”
“There’s no sudden movement towards taking up LTO 5.”
Indeed, Holloway says Spectrum’s clients, who typically come to the company to move data from old tape and disk to more modern formats, are moving away from tape.
“Virtual tape libraries are becoming a lot more acceptable,” he says. “We see VTL being embraced more by our clients and that has impacted tape.”
“We used to move a million dollars in tape each year but we have seen that fall 25% or 30% a year as VTL becomes more popular.”
“The environmental footprint of disk decreasing helps as well and this will impact uptake of LTO 5,” he adds.
LTO consortium representatives Bruce Master and Tom Hammond counter that the new capabilities of LTO 5 are designed to ensure that tape remains a viable archival medium capable of “catching up” with the quantities of data being created and stored on disk.
“If an organisation uses 50TB of disk they want a single tape library to cope with that,” the pair said.
“There is now a certain set of customers in the mid-to-upper range who need faster access to the data. In those cases we see them implementing disk or disk inside a VTL, then moving to tape because they need to retain data for the long term.”
“And for lower service-level applications, the data goes directly to tape.”
Spectrum Data’s Chris Holloway agrees, as he has found some of the company’s clients in financial services industries continue to prefer tape.
Body: But Holloway says that some of those clients do not use LTO for their archives, preferring other tape media like IBM’s 3592 tape cartridges.
“LTO has its place in the commercial environment,” he says. “But is not an enterprise technology. LTO hardware is midrange libraries and silos. 3592 has the big silos at 2000 slots and above.”
LTO may therefore be best-suited, in its early days, as a backup medium for smaller businesses, says IBM’s Derrett.
“For the medium-sized shop faster, larger tape will simplify things, because where they used to have a small library and a few cartridges, they will now be able to use one tape.”
“The speed of LTO 5 will mean they can continue to work with simple principle of put on the backup, come in next day and everything is done. That puts simple backup into the realms of reality for SMEs. For bigger shops it simply reduces the backup window.”
And that smaller window may not be enough to make up for the other complications that come with a new generation of tape.
“A customer needs to think about backwards capability, because if you go to LTO 5 you cannot even read LTO 2 any more,” Derrett says. “So maybe LTO 4 is the better choice under those circumstances.”