Stuck on tape

As disk prices fall, many organizationsare switching from tapestorage to disk-based virtualtape libraries (VTL) as the preferredmeans of long-term data storage. TheAgriculture Department's Food and NutritionServices (FNS) in Alexandria, Va., forexample, started using NetApp VirtualFile Manager to back up its servers onto aset of NetApp FAS200 series devices.'Since doing disk-to-disk backup,tapes are hardly being used,'said Harold Russell, a WyandotteNetTel project manager workingat FNS.Despite predictions of their imminentdemise, however, tape libraries' which have been aroundsince Remington Rand built theUniservo in 1951 ' still have a placein the data center.FNS has two Spectra Logic Spectra20K tape libraries, each with four drivesand 24 tape slots, which it still uses forbacking up its test environment. And nextsummer, FNS will start doing monthlyarchives of its e-mail messages to meet theseven-year retention requirements.'Knowing the federal government, we willprobably never completely dump tapes, unlesswe switch to another durable type ofmedia like optical disks,' Russell said.'Tape is the most cost-effective storage outthere, and people will continue to leveragetape products for many years to come,'said Tom Coughlin of consulting firmCoughlin and Associates.Robert Stevenson, managing director ofstorage research at TheInfoPro, said tapeusage is particularly strong among largeorganizations.'They are starting to see more regulatorycompliance requirements, so we are notseeing a reduction in tape growth,' he said.Smaller organizations, however, areadopting VTLs as an alternative to tape.Those that have 15,000 to 20,000 tapesare weaning themselvesoff tape, and many could be completelyoff tape in about five years. Thosewith less than 15,000 tapes are using VTLsas a storage consolidation method.'They like VTLs, not so much becausethey have a bottleneck in terms of theirtape drives being busy, but they have differenttape drive technologies,' Stevensonsaid. 'They are using VTL to consolidateonto one single tape format while beingmore aggressive on trying to minimize tapecreation.'Coughlin said one main driver in keepingtape is not only the equipment and suppliescost but also the power consumptiondifferences between disk and tape storage.'As fuel prices go up and energy costs increase,tape automation systems can be abig part of using your resources more effectivelyand lowering your total operatingcost,' he said.Analysts David Reine and Mike Kahn ofthe Clipper Group compared costs and energyconsumption for five-year data storageon Serial Advanced Technology Attachmentdisks compared with LinearTape-Open Generation 4 (LTO-4) tape(GCN.com/1191.) The study assumedan initial storage base of 50T thatgrows 50 percent annually and runs dailydifferential backups containing 5 percentof the total data, weekly full backups storedfor 13 weeks and quarterly archives of thedata. The archives were either stored onthe disk array or moved to near-line storagein a tape library. Reine andKahn found that storing the quarterlyarchives on the disk array cost23 times as much as moving themto tape and that energy costs were290 times as high.Disk-to-disk (D2D) backup, theyconcluded, 'is not a replacement fortape; it should be a complement to tape.The costs associated with a pure D2D scenarioare simply too great for any midsizedor larger business to consider usingthis technology to establish a comprehensivepolicy to save their entire data storefor any extended length of time.'Although tape automation systems aremature product lines, there are still incrementalimprovements being made to theirfunctionality.The biggest change recently was the introductionof LTO-4 in 2007. The new formatdoubled the capacity of the third generationof LTO (LTO-3) tapes to 800Gnative storage and boosted the uncompressedtransfer rate to 120 megabits/sec.Sun Microsystems and IBM have alreadygone beyond the LTO-4 capacity with newdrives they introduced in July. Sun's newStorageTek T10000B tape drive has a 1Tnative capacity, double that of its predecessor,and costs $37,000. IBM's TS1130 drive is also 1T and costs $39,500. Both use 4gigabits/sec Fibre Channel or Fiber Connectivityconnections.LTO-4 retained the write-once, readmanyfunctions that came out of LTO-3tapes to comply with certain data retentionregulations. But for the first time, italso includes built-in encryption ' AdvancedEncryption Standard 256, approvedby the National Institute of Standardsand Technology and which meetsthe requirements of Federal InformationProcessing Standard 140-2.Stevenson said the release of LTO-4 hasbeen a driver in federal agencies' increasedtape library purchases.'We are seeing a heavy amount of refreshrates and moving to LTO-4 drives to minimizethe number of tape drives they have tolicense,' he said. 'The encryption feature isalso a big component in the federal sector.'The other key factor in making tape librarydecisions is data deduplication. Withrapidly expanding storage capacity, deduplicationis increasingly important,whether it is part of the tape library or astand-alone product.If storage volumes stayed constant, fallingVTL prices would make them a viableoption to replace tape. But with storagerequirements growing at a 50 percentannual rate, tape still has its place. Butwhere tape fits into the overall solution ischanging.'With the push toward data center consolidations,the influx of servers withinthe primary hosting centers with theirown separate backup solutions overwhelmedthe initial infrastructure,' saidJohn Kozitzki, enterprise backup and recoverymanager for Michigan. 'Backupwindows were continually being missed,success rates were in the 70 [percent] to80 percent range, and backup administrationstaff was having a hard timekeeping up with configuration andmaintenance.'Kozitzki set up an enterprise backupsystem using both disk and tape. Thestate uses Symantec Netbackup runningon 22 assorted Sun servers. Netbackupwrites to EMC Symmetrix diskstorage volumes for disk-to-disk backups,EMC EDL4400 disk libraries forvirtual tape use ' disk-to-disk or diskto-disk-to-tape ' and to a Sun StorageTekSL8500 tape library with 60drives and 5,000 slots, using 9940B orT10000 tape.'We currently configure servers that requireenterprise backup and recoveryservices based on the amount of storageallocated to the server, the retention policyrequired, and the recovery point/recoverytime objectives,' Kozitzki said. 'Thisinformation is taken into considerationwhen crafting a solution for our agencypartners.'The tape library is used for direct nearlinestorage and off-site archiving onservers that have retention policies greaterthan 30 days. With the new setup, he runsabout 20,000 jobs each week to back up200T of data and is now achieving a 96percent to 98 percent success rate.'Moving to a standardized, consolidatedenterprise solution made sense,' Kozitzkisaid. 'It allowed for easier administration,increase in success rates and made it morescalable.'