Users weigh in on tape-vs.-disk backup debate

By Heidi Biggar

In a recent InfoStor survey, industry analysts and integrators gave disk-based backup high marks. In fact, four out of eight respondents said disk-based backup should be given "high" implementation priority this year (see "Analysts share 2002-03 storage perspectives," February 2003, p.1).

But how popular is disk-based backup, really? Are end users embracing it, and if so, how has it affected their use of tape for backup?

To find out the answers to these questions and others, InfoStor polled its readers about their past, current, and future backup challenges and plans. The results revealed an industry in flux—one that is neither immovably loyal to tape, nor solidly committed to disk for backup.

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For example, while 71% of survey respondents said they planned to purchase tape backup products over the next six to 12 months, 64% also said they planned to purchase disk-based backup products in the same time frame (see figure on p. 13). Similarly, 29% of respondents said they had no plans to purchase tape backup products over the next six to 12 months, while 36% said they had no plans to purchase disk-based backup products.

However, when respondents were asked about the specific changes they planned to make to their backup environments (e.g., purchase more/less tape, disk, etc.) in the coming year (see figure on p. 1), 56% said they planned to purchase more tape, 42% percent said they planned to purchase disk-based backup products instead of tape, 14% said they planned to purchase less tape, and 4% said they planned to outsource their backup to a third-party provider (e.g., Iron Mountain, LiveVault, EVault, etc.).

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But perhaps most interesting, 52% of those respondents said they planned to increase their use of snapshot, mirroring, and other replication techniques. While not central to the disk-versus-tape debate, the result is worth noting since it speaks to the viewpoint that the future of "data protection" may lie with synchronous or asynchronous mirroring/copying, not disk or tape.

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As for factors that influence the type of backup purchase, backup speed, capacity, and reliability topped the list (see figure). Recovery speed came in a close fourth with 66% of the vote, followed by ease of use (48%), total cost of ownership or return on investment (31%), company reputation (30%), investment protection (25%), and space issues (21%). Interestingly, removability, which is often listed as one of tape's key benefits over disk, wasn't considered to be a key purchasing factor, garnering just 14% of the votes.

Similarly, of those respondents who said they planned to switch tape formats over the next six to 12 months, 85% said they were doing so for capacity reasons, while 73% said they were looking to improve performance. Respondents also pointed to issues with reliability (35%) and investment protection (27%). Brand name was not a concern.

In line with these results, 65% of survey respondents who said they were looking to switch tape formats in the coming year said they planned to upgrade to super drive technology (e.g., SuperDLTtape, LTO). About 34% of respondents said they planned to switch to LTO, while 31% said they planned to invest in SDLT. [Note: S-AIT was not shipping at the time the survey was conducted.]

These results parallel analyst forecasts for the industry, which call for positive growth in the "super drive" category despite a double-digit decline in overall tape shipments and revenue worldwide. According to Freeman Reports, unit shipments of SDLT and LTO drives are expected to increase more than 100% this year, with LTO maintaining its market leadership position (see "Sony bests LTO, SDLT with 500GB S-AIT drive," p. 12).

Not surprisingly, DLT and 4mm DDS/DAT were the primary tape formats used in respondents' backup environments. Fifty-one percent of respondents checked off DLT as their primary backup target, while 31% listed 4mm DAT. Only 39% of respondents said SDLT or LTO was currently their primary tape backup medium.

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Due to relative immaturity of the disk-based backup market, questions about end-user adoption were limited to their current and future disk-based plans. About 64% of respondents said they planned to purchase disk-based backup products in the next six to 12 months. Meanwhile, of the 223 respondents who said they had already purchased such products, 47% said they bought them from Quantum, while 27% said Sony.

EMC, Network Appliance, and StorageTek were also commonly cited with 32%, 28%, and 27% of respondents listing them as suppliers of disk-based backup technology. Start-ups Alacritus, Avail, Avamar, Connected, Nexsan, Okapi Software, and SwapDrive also made the list with a few percentage points each, as did online providers EVault and LiveVault.

Survey profile

Number of respondents: 783

Type of respondents

End users: 55%
Resellers/integrators: 33%
OEMs: 13%

Company size (number of employees)

Less than 250: 49%
250-999: 12%
1,000 to 9,999: 19%
10,000 or more: 20%

Annual budget for storage products/services

Under $99,000: 39%
$99,000 to $499,999: 19%
$500,000 to $1 million: 14%
$1 million to $4.9 million: 15%
$5 million or more: 14%
Source: InfoStor backup survey, March 2003

Recent ATA product news

EMC broadens ATA support

EMC last month made two of its Clariion arrays—the CX400 and CX600—available in parallel ATA configurations (support for Serial ATA is planned). EMC first integrated parallel ATA drives last year, when it introduced Centera, an ATA-based repository for fixed-content data.

The Clariion arrays are equipped with Maxtor 250GB, 5,400rpm parallel ATA drives. EMC officials say the decision to integrate Fibre Channel and ATA drives into its Clariion family (both ATA and Fibre Channel drives can be used in a single system) is an effort to help users bring offline tape-based backup and primary data online for ready access.

The two new Clariion systems have been certified to back up to disk using EMC Data Manager (EDM), as well as non-EMC backup applications, such as CommVault Galaxy, Computer Associates BrightStor ARCserv Backup and BrightStor Enterprise Backup, Legato NetWorker, and Veritas NetBackup and Backup Exec.

The ATA arrays also allow users to do local and remote replication at lower price points. A 10TB ATA-based Clariion array is priced from $170,000.

Legato gets into the ATA act

Among the new features of the recently released Legato NetWorker 7.0 is an enhanced DiskBackup Option. The company says that by allowing users to write and read multiple data streams to and from a variety of new ATA-based disk-based backup devices—particularly EMC Clariion, StorageTek BladeStor, and NetApp NearStore products—it has raised the performance bar for disk-based recovery, staging, and cloning.

Besides improved disk support, NetWorker 7.0 also features new support for Windows 2003 Server, Enterprise Linux, and Mac OS X, improved tape sharing, and extended NAS support (e.g., improved restore performance at the directory level, automated tape cloning for disaster recovery, and new support for IBM-AIX, and HP Tru64).

This article was originally published on April 01, 2003