Two responses that are continually cited among the top five IT priorities identified by respondents in ESG’s annual IT spending intentions survey are improving data backup and recovery and managing data growth (see Figure 1). 1 It’s not a coincidence that these responses often appear together in ESG survey results since data growth has a direct impact on an organization’s ability to back up and restore data in a timely manner.
Historically, data growth in a production environment meant adding more disk to the primary storage environment, which in turn meant adding more tape or secondary disk storage to the backup environment. Now, this dynamic is changing, as new enhancements in LTO Ultrium technology are blurring primary and secondary storage lines and giving customers more choices in how they store and protect their business-critical data.
The Solution: Linear Tape-Open (LTO) Deployments
Originally released in 2000, the Linear Tape-Open (LTO) Ultrium technology was developed as an alternative to proprietary tape formats. Development, licensing, and certification of media and drives are governed by the LTO Consortium, which maintains rigid interoperability standards so that drives and cartridges from different vendors are expected to be interchangeable. Now in its seventh generation of availability, LTO Ultrium high-capacity magnetic tape storage technology is capable of storing 15 TB of data on a single cartridge with up to 750MB/s transfer rate. 2 Key metrics Include:
- A development roadmap for the technology with defined capacity capabilities all the way out to LTO-10.
- An algorithm that delivers 2.5:1 lossless compression for LTO-6 and LTO-7 and 2:1 compression for older generations.
- Compatibility rules that define Ultrium technology interoperability:
o A drive can read data from media in its own generation and two prior generation.
o A drive can write data to media in its own generation and the immediate prior generation.
Initially, the technology was predominantly used as a target in data protection solutions, but the introduction of the Linear Tape File System (LTFS) in generation five expanded the scope of LTO in the modern data center significantly. Now, organizations are leveraging it to address the challenges of managing ever-growing tertiary and even primary storage. As shown in Figure 2, LTO technology can be deployed in diverse configurations from small standalone drive environments, to mid-market autoloader and library solutions, all the way to multi-frame enterprise library infrastructures. Next-generation data center enablement features include:
- Write Once Read Many (WORM) technology introduced in LTO-3. This is typically used for legal record keeping.
- Application-managed, natively-enabled tape drive level AES-GCM encryption introduced in LTO-4.
- Partitioning introduced in LTO-5, which enabled the tape to be divided into separately writable areas.
- Linear Tape File System (LTFS), a self-describing tape file system made possible by the partitioning feature
ESG Lab performed hands-on evaluation and auditing of LTO Ultrium technology at a Hewlett Packard Enterprise facility in Fort Collins, CO. Testing was designed to demonstrate reliability, improved performance and capacity, and new features that move the technology beyond only data protection and enable its use in multiple storage configurations.
Modern Use Case
ESG Lab started its validation of LTO technology by reviewing how newer generation LTO features are being leveraged in today’s data center. The introduction of partitioning, in LTO generation five, enabled many of these modern use cases. Partitioning allows formatting the tape into one section that holds content or data and another section that holds an index of that content, thereby creating self-describing media. Partitioning made the Linear Tape File System (LTFS) possible. LTFS works in conjunction with LTO drive and media technology to make the device look like a typical storage device to the underlying operating system. Once configured, files can be simply copied to and from the device just like with any disk drive.
ESG Lab deployed a simple LTFS configuration on a Windows server with a SAS connected LTO-6 standalone tape drive. We simply downloaded and installed the free LTO-6 driver and LTFS utilities and then configured and mounted the tape drive as a 2.29TB volume on the test environment Windows server. Best practices recommend moving files that require modification to a random access device while using this configuration as a local or portable archive type solution and for large sequential read operations.
Free downloadable LTFS solutions include:
- Hewlett Packard Enterprise StoreOpen Standalone and Automation.
- IBM Linear Tape File System Single Drive Edition.
- Quantum Linear Tape File System.
Next, ESG Lab explored expanding the local capabilities of LTFS to a NAS solution. Here, LTFS-formatted media is stored in an automated LTO tape library and is used as high-capacity, cost-efficient back-end storage to a front-end NAS server. The NAS server manages the presentation of data to the end-users over the corporate LAN via the CIFS/NFS protocols. It also manages the movement of active data between LTFS storage and disk cache. This process enables active data (such as those files currently being modified) to be serviced from a small amount of disk cache on the NAS server, and less active data to be stored on large-capacity LTO media in the automated library as an active archive.
ESG Lab reviewed best practices for tape in today’s data protection solutions. Even with the adoption of disk and cloud, tape remains a major component in many data protection environments. It provides customers with a fast, highly reliable, and portable storage media. A well-designed and balanced data protection architecture often leverages tape library solutions for active archive and consolidated output. Large sequential data streams and groups of disk backups with high throughput requirements can be staged to the library’s portable media for efficient offsite data transfer. Less bandwidth-intensive workloads are sent directly to the cloud.
When it comes to reliability in tape-based data storage solutions, the number one priority should be the ability to access data when needed. A tape drive may fail, but if the data can still be read back with another drive, then retrieval is successful. Other important considerations include media durability, media shelf life, drive reliability, and probably most importantly, end-user best practices.
ESG Lab began its review of LTO solution reliability by interviewing members of the quality assurance team from an LTO Program participant, along with exploring LTO media characteristics. LTO media was designed on the premise that it would be loaded into a device, written to, removed, moved, stored, recalled, and reloaded into a device when data needed to be retrieved. With that in mind, each consortium member is constantly working to keep LTO media highly reliable, portable, and rugged enough to be moved without impacting data integrity.
LTO Ultrium media reliability starts with format design. First, data is spread across multiple channels (8, 16, or 32, depending on generation) to protect against single-head element or media defects. Then error detection/correction code (ECC) is applied at two levels. Level one ECC rewrites the data to another location further down the original track. Level two ECC rewrites the data across multiple tracks and allows for data recovery in the event of a totally bad track. The process uses read-while-write verification where the read head checks the validity of each dataset written. If a data sub-set logs an error, it is automatically rewritten. These format design features produce a one in 1019 bit-error-rate (BER) for LTO-7 media. In layman’s terms, this means that it would take 130 tape drives writing data continually for one year to encounter an error that could not be fixed by ECC. As shown in Figure 7, you are more likely (1 in 1016) to hit an uncorrectable error in your enterprise disk environment. In fact, you would have a much higher probably of:
- Getting hit by lightning; the odds are one in a million.
- Getting killed by a shark; the odds are one in 11.5 million.
- Winning a multi-million dollar lottery; the odds are 1 in 259 million.
Next, ESG Lab reviewed the product testing methodology used to ensure the reliability of the tape drives that are used to read and write data on LTO Ultrium media. For this testing, three high-level concepts were used:
- Mean time between failures (MTBF) is used to show that the product will achieve expected reliability.
- Design verification covers a full suite of ambient, environmental, and regulatory compliance tests.
- Field warranty and repair data is collected and monitored to validate annual failure rates.
The result of an environmental LTO-6 Constant Transfer Rate test is displayed in Figure 8. This is just one of the many rigorous tests ESG Lab audited during the review to validate the commitment of LTO Consortium members to delivering highly reliable solutions. It shows the transfer rate achieved when writing full volumes to multiple green cartridges, a process often used in archiving solutions.4 Testing results are expressed in terms of the difference from the theoretical maximum native value of 160 MB/sec for LTO-6 tape drives. It should be noted that, for the duration of the test, the drive maintained extremely consistent throughput (e.g., after writing 2,000 green tape cartridges).
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