Storage techniques for Big Data, IBM Research Zurich

The rapid growth of data with annual growth rates of 50% and more, together with the requirement to contain the cost of data storage at a manageable level, requires efficient data storage, including compression and data deduplication, but also the careful placement of data on the best suited storage medium. In order to find the optimal data placement on different storage tiers (e.g. SSD, disk, tape) as shown at right in terms of cost and performance, it is crucial to understand the access patterns to data. This knowledge can be utilized not only for data placement, but also for intelligent caching and pre-fetching of data, which was one of the research goals of the DOME project.

Magnetic tape is the storage medium that offers by far the lowest cost of ownership for long term storage. An analysis of the tape market showed that most of today’s tape drive and media characteristics (capacity, throughput, longevity, cost, etc.) satisfy customer requirements for use cases such as backup and archival storage. However, there is a strong demand for improvements in tape manageability and usability, for example, a non-proprietary, simple and cost-effective integration of tape storage in the tiered storage hierarchy or even into cloud storage systems. This seamless tape integrating can be done by utilizing the open Linear Tape File System (LTFS) format developed by IBM together with IBM’s General Parallel File System (GPFS).

Such integration enables tape systems to play an important role in active archives, in which data can be seamlessly migrated to the most appropriate storage tier (e.g. SSD, HDD, tape) and where the data is always online and accessible to the users from all storage tiers through a common file system that represents all the tiers in a single name space. Big Data analytics has become a significant driver for large storage capacity requirements and the demand for highly optimized and responsive storage systems. At the same time, data analytics can also be an enabler for an optimized data management and storage system.

Tiered storage

In the field of tiered archival storage we address new storage requirements posed by the companies and organizations that base their operations and mission-critical businesses on the ability to store and process vast amounts of data efficiently and cost-effectively.

Storage requirements

Data needs to be easily available through a standard interface and via a single name space.
Data needs to be protected continuously and stored for a long time.
Storage costs and access requirements need to be optimized based on time-varying data usage or value.
System should scale to a very large number of files or data objects.

Scalable active archive is another term used for storage systems that satisfy these requirements. Our research on this topic focuses on integrating solid-state drive, disk, and tape tiers under a single name space, and providing additional management functions for moving the data between the tiers. To provide a single name space, reliability, scalability, and data management, we leverage IBM’s General Parallel File System (GPFS) technology and OpenStack Swift. To add a reliable and cheap storage tier, we integrate the open-standard Linear Tape File System (LTFS) technology.

Tiered storage combines different types of storage media, preferably under a single name space and using a standard interface, equipped with data lifecycle management functions for migrating data between different storage tiers.

Project

LTFS EE
Building a clustered file system on top of flash, disk and tape

GLUFS is the research project on integrating tapes formatted in accordance with the Linear Tape File System (LTFS) standard into the General Parallel File System (GPFS) as a tape storage tier for migration and backup. Some of the GLUFS features are marketed by IBM as Linear Tape File System Enterprise Edition (LTFS EE) — a distributed file system on top of flash, disk, and tape.

GPFS is IBM’s disk cluster file system, which is extremely scalable. Seamlessly integrating LTFS tapes into GPFS makes tape look like disk, makes it easy to use, and creates a common name space across disk and tape. Flexible migration policies allow administrators to optimize cost, access time, and power consumption by moving data between disk and tape. When it comes to big data, tape is the most efficient storage medium whenever applications can live with the resulting access latency. GLUFS makes tape easy to use and scales disk clusters to truly big active archives at low cost.

Key features

Global name space. Common global name space across disk and tape at GFPS level.
Simplified infrastructure and scalability. Metadata of migrated files is kept in GPFS so there is no need for external metadata servers. This allows the system to scale with the number of nodes, drives, and tapes.
Open format on portable media. Increased flexibility due to LTFS being an open standard.
Import/export and disaster recovery. Tapes can be exported from or imported into a GLUFS system. Tapes remain self-contained, including all meta-data from the original name space. The global name space can be recreated quickly from the meta-data on the tapes. In other words, the system becomes operational and the files become accessible without having to first move the data from the tapes.
Multi-node and multi-library support.Multiple GPFS nodes, multiple tape libraries, across multiple locations can be connected.
Flexibility. Cost/performance efficiency can be adjusted by disk/tape ratio and migration policies.
Simplified tape management. Makes tape management transparent to user by handling: cartridge pooling, reclamation, reconciliation, resource scheduling, replicas, fill policies etc.

GLUFS

GLUFS: Integration of disk and tape (GPFS and LTFS) within a distributed file system that provides a single name space and data lifecycle management (migration between disk and tape) functions.

Project

IceTier
A distributed object storage on top of disk and tape

The goal of the IceTier project is to build a standalone, archival object storage service based on tape storage media. One use case of a tape-based object storage is a standalone service that stores objects directly on tape with disk being optionally used for caching. In another use case, the “cold” objects from the highly available, disk based, primary object store are migrated to the low-cost tape-based object storage. In yet another use case, disk and tape are integrated within the same object storage service, allowing internal data lifecycle management between disk and tape.

Cognitive storage

Big advances in storage technologies and in storage management have enabled storage administrators to keep up with the exponential data growth over the decades, and to keep the ever increasing storage system complexity manageable so far. However, the question arises whether these advances in storage technologies will be sufficient to accommodate the future data growth and to effectively handle the ever increasing system complexity.

Another question is whether the future storage capacity growth will fall behind data growth rates, meaning that the standard model of storing all data forever will no longer be sustainable due to a shortage of available storage resources. In other words, we must decide whether we even need or want to store all the data that is being generated today and will be in the future.

What we do under the umbrella of cognitive storage is to make an attempt to understand the value and relevance of the data and, based on this data-specific knowledge, determine where, with how much redundancy, and for how long to store the data. Depending on the distribution and evolution of the relevance of the data, there appears to be a large potential for significant storage capacity savings.

Many challenges have to be addressed on the way to a fully-fledged cognitive storage system, most prominently whether and how the data value can actually be defined in a systematic way, whether and how it can be obtained automatically, how it will change over time, whether a future storage system should be able to extract relevant information from data autonomously and store it in a modified compact form, and many more.

Storage reliability

Modern data storage systems are extremely large and consist of several tens or hundreds of storage nodes. In such systems, node failures are daily events, and safeguarding data from them poses a serious design challenge. Data redundancy, in the form of replication or advanced erasure codes, is used to protect data from node failures. By storing redundant data across several nodes, the redundant data on surviving nodes can be used to rebuild the data lost by the failed nodes. As these rebuild processes take time to complete, there exists a chance of additional node failures occurring during rebuild. This eventually may lead to a situation in which some of the data becomes irrecoverably lost from the system.

Our activities in storage system reliability investigate novel methods to address issues encountered in large size storage installations. In particular, we focus on the occurrence of data loss and on methods to improve reliability without sacrificing performance and storage efficiency. We have shown that spreading the redundant data corresponding to the data on each node across a higher number of other nodes, and using a distributed and intelligent rebuild process will improve the system’s mean time to data loss (MTTDL) and the expected annual fraction of data loss (EAFDL).

In particular, declustered placement, which corresponds to spreading the redundant data corresponding to each node equally across all other nodes of the system, is found to have potentially significantly higher MTTDL and lower EAFDL values than other placement schemes, especially for large storage systems. We have also developed enhanced recovery schemes for geo-replicated cloud storage systems where network bandwidth between sites is typically more scarce than bandwidth within a site, and can potentially be a bottleneck for recovery operations.

distributed rebuild model

Example of the distributed rebuild model for a two-way replicated system. When one node fails, the critical data blocks are equally spread across the n−1 surviving nodes. The distributed rebuild process creates replicas of these critical blocks by copying them from one surviving node to another in parallel.

Ask the expert

Mark A. Lantz

Mark A. Lantz
IBM Research scientist

Additional resources

Publications

2016
1. G. Cherubini, J. Jelitto, V. Venkatesan,
  Cognitive Storage for Big Data,
  IEEE Computer Magazine 49(4), 2016.
2. R.D. Cideciyan, S. Furrer, M.A. Lantz,
  3D Product Codes for Magnetic Tape Recording,
  in Digest Book, The 27th Magnetic Recording Conference (TMRC), 91-92, 2016.
3. R.D. Cideciyan, S. Furrer, M.A. Lantz,
  Product Codes for Data Storage on Magnetic Tape,
  IEEE Transactions on Magnetics PP(99), 2016.
4. J.B.C. Engelen, V.P. Jonnalagadda, S. Furrer, H.E. Rothuizen, M.A. Lantz,
  Tape Head with Sub-Ambient Air Pressure Cavities,
  IEEE Transactions on Magnetics 52(11), 3301810, 2016.
5. G. Cherubini, A. Pantazi, M. Lantz,
  Near-optimal tape transport control with feedback of velocity and tension,
  Proc. 7th IFAC Symposium on Mechatronic Systems, Mechatronics 2016, Loughborough University, UK, pp. 19-25, September 2016.
6. G. Cherubini, S. Furrer, M.A. Lantz,
  High-Rate Skew Estimation for Tape Systems,
  Proc. 7th IFAC Symposium on Mechatronic Systems, Mechatronics 2016, Loughborough University, UK, pp. 7-12, September 2016.
7. H. Yang, J.B.C. Engelen, W. Häberle, M.A. Lantz, S. Müftü,
  Lateral Friction Behavior of a Thin, Tensioned Tape Wrapped over a Grooved Roller: 4 Experiments and Theory,
  J. Tribol. 139(2), 021605, Paper No: TRIB-15-1449, 2016.
8. I. Iliadis, Y. Kim, S. Sarafijanovic and V. Venkatesan
  Performance Evaluation of a Tape Library System,
  Proc. IEEE Int’l Symposium on Modeling, Analysis, Simulation of Computer and Telecommunication Systems (MASCOTS 2016), pp. 59-68, 2016.
2015
1. I. Koltsidas, S. Sarafijanovic, M. Petermann, N. Haustein, H. Seipp, R. Haas, J. Jelitto, T. Weigold, E. Childers, D. Pease, E. Eleftheriou,
  Seamlessly Integrating Disk and Tape in a Multi-tiered Distributed File System,
  ICDE 2015, 31st IEEE International Conference on Data Engineering, 2015.
2. J.B.C. Engelen, M.A. Lantz,
  Asymmetrically Wrapped Flat-Profile Tape–Head Friction and Spacing,
  Tribol. Lett. 59(16), 2015.
3. M.A. Lantz, S. Furrer, J.B.C. Engelen, A. Pantazi, H.E. Rothuizen, R.D. Cideciyan, G. Cherubini, W. Haeberle, J. Jelitto, E. Eleftheriou, M. Oyanagi, A. Morooka, M. Mori, Y. Kurihashi, T. Kaneko, T. Tada, H. Suzuki, T. Harasawa, O. Shimizu, H. Ohtsu, H. Noguchi,
  123 Gb/in² Recording Areal Density on Barium Ferrite Tape,
  IEEE Transactions on Magnetics 51(11), 2015.
4. S. Furrer, A. Pantazi, G. Cherubini, M. Lantz,
  Resolution Limits of Timing-Based Servo Schemes in Magnetic Tape Drives,
  IEEE Transactions on Magnetics 99, 2015.
5. M.A. Lantz, S. Furrer, J.B.C. Engelen, A. Pantazi, H.E. Rothuizen, R.D. Cideciyan, G. Cherubini, W. Haeberle, J. Jelitto, E. Eletheriou, M. Oyanagi, A. Morooka, M. Mori, Y. Kurihashi, T. Kaneko, T. Tada, H. Suzuki, T. Harasawa, O. Shimizu, H. Ohtsu and H. Noguchi,
  Technologies for Magnetic Tape Recording at 100 Gb/in² and beyond,
  Digest of Intermag 2015, Beijing, China.
6. S. Furrer, A. Pantazi, G. Cherubini and M.A. Lantz,
  Resolution Limits of Timing-Based Servo Schemes in Magnetic Tape Drives,
  Digest of Intermag 2015, Beijing, China.
7. J.B.C. Engelen, V.P. Jonnalagadda, S. Furrer, H.E. Rothuizen, M.A. Lantz,
  A Non-Skiving Tape Head with Subambient Air Pressure Cavities,
  Digest of Intermag 2015, Beijing, China.
8. H. Yang, J.B.C. Engelen, A. Pantazi, W. Häberle, M.A. Lantz, Sinan Müftü,
  Mechanics of Lateral Positioning of a Translating Tape due to Tilted Rollers: Theory and Experiments,
  International Journal of Solids and Structures 66, 88–97, 2015.
9. J.B.C. Engelen, S. Furrer, H.E. Rothuizen, M.A. Lantz,
  Where Tape and Hard-Disk Technology Meet: The HDD Head-Tape Interface,
  IEEE Transactions on Magnetics 51(7), 2015.
10. S. Furrer, M.A. Lantz, J.B.C. Engelen, A. Pantazi, H.E. Rothuizen, R.D. Cideciyan, G. Cherubini, W. Haeberle, J. Jelitto, E. Eleftheriou, M. Oyanagi, Y. Kurihashi, Takahiro Ishioroshi, T. Kaneko, H. Suzuki, T. Harasawa, O. Shimizu, H. Ohtsu, H. Noguchi,
  85.9 Gb/in² Recording Areal Density on Barium Ferrite Tape,
  IEEE Transactions on Magnetics 51(4), 3100207, 2015.
11. A. Pantazi, S. Furrer, H.E. Rothuizen, G. Cherubini, J. Jelitto and M.A. Lantz,
  Nanoscale track-following for tape storage,
  American Control Conference (ACC), 2837–2843, 2015.
12. G. Cherubini, S. Furrer, J. Jelitto,
  High-Performance Servo Channel for Nanometer Head Positioning and Longitudinal Position Symbol Detection in Tape Systems,
  IEEE/ASME Trans. Mechatronics, 2015
13. I. Iliadis and V. Venkatesan,
  Rebuttal to ‘Beyond MTTDL: A Closed-Form RAID-6 Reliability Equation’,
  ACM Trans. Storage 11(2), 1-10, 2015.
14. I. Iliadis and V. Venkatesan,
  An Efficient Method for Reliability Evaluation of Data Storage Systems,
  Proc. 8th International Conference on Communication Theory, Reliability, Quality of Service (CTRQ), 6-12, 2015.
15. I. Iliadis, J. Jelitto, Y. Kim, S. Sarafijanovic, V. Venkatesan,
  ExaPlan: Queueing-Based Data Placement and Provisioning for Large Tiered Storage Systems,
  Proc. of the 22nd IEEE Int’l Symposium on Modeling, Analysis, Simulation of Computer and Telecommunication Systems (MASCOTS), 218-227, 2015.
16. I. Iliadis, V. Venkatesan,
  Most Probable Paths to Data Loss: An Efficient Method for Reliability Evaluation of Data Storage Systems,
  IARIA: International Journal on Advances in Systems and Measurements 8(3&4), 178-200, 2015.
2014
1. S. Furrer, M.A. Lantz, J.B.C. Engelen, A. Pantazi, H.E. Rothuizen, R.D. Cideciyan, G. Cherubini, W. Haeberle, J. Jelitto, E. Eleftheriou, M. Oyanagi, Y. Kurihashi, T. Ishioroshi, T. Kaneko, H. Suzuki, T. Harasawa, O. Shimizu, H. Ohtsu and H. Noguchi,
  85.9 Gb/in² Recording Areal Density on Barium Ferrite Tape,
  Digest of Magnetic Recording Conf. “TMRC,” 79-80, 2014 (invited).
2. R.D. Cideciyan, S. Furrer, M.A. Lantz,
  Iterative Hard-Decision Decoding of Reed-Solomon Product Codes in Magnetic Tape Recording,
  Digest of Magnetic Recording Conf. “TMRC,” 127-128, 2014.
3. S. Furrer, G. Cherubini, A. Pantazi, M.A. Lantz,
  Performance Limits of Timing-Based Servo Schemes in Magnetic Tape Recording,
  Digest of Magnetic Recording Conf. “TMRC,” 115-116, 2014.
4. J.B.C. Engelen, S. Furrer, H.E. Rothuizen, M.A. Lantz,
  Where Tape and Hard-Disk Technology Meet,
  Digest of Magnetic Recording Conf. “TMRC,” 111-112, 2014.
5. A. Pantazi, M.A. Lantz,
  Tape Drive Track Following Using Cascade Control,
  Proceedings 19th IFAC World Congress, 2014.
6. A. Pantazi, G. Cherubini, E. Ogura, J. Jelitto,
  Tape Transport Control Based on Sensor Fusion,
  Proceedings 19th IFAC World Congress, 2014.
7. M.A. Lantz and E. Elefteriou,
  Future Scaling Potential of Particulate Media in Magnetic Tape Recording,
  In: Handbook of Magnetic Materials, Vol. 22, Chapter 3, Elsevier, 2014.
  Print Book ISBN : 9780444632913, eBook ISBN : 9780444632937.
8. J.B.C. Engelen, S. Furrer, H.E. Rothuizen, M.A. Lantz,
  Flat-Profile Tape–Head Friction and Magnetic Spacing,
  IEEE Transactions on Magnetics 50(3), Article No. 3301106, 2014.
9. T. Mittelholzer, R.D. Cideciyan,
  Enumerative Modulation Codes Based on Sliding-Window Substitutions,
  IEEE International Symposium on Information Theory Proceedings (ISIT), 2014.
10. I. Iliadis and V. Venkatesan,
  Expected Annual Fraction of Data Loss as a Metric for Data Storage Reliability,
  Proc. 22nd IEEE Int’l Symposium on Modeling, Analysis, Simulation of Computer and Telecommunication Systems (MASCOTS), 375-384, 2014.
11. I. Iliadis, D. Sotnikov, P. Ta-Shma, V. Venkatesan,
  Reliability of Geo-replicated Cloud Storage Systems,
  Proc. 20th IEEE Pacific Rim International Symposium on Dependable Computing (PRDC), 169-179, 2014.
12. R. D. Cideciyan, R. Hutchins, T. Mittelholzer, S. Ölçer,
  Partial Reverse Concatenation for Data Storage,
  Proceedings of Asia-Pacific Signal and Information Processing Association, 2014 Annual Conference and Summit (APSIPA), 2014.
2013
1. A. Pantazi and M. Lantz,
  Vibration Compensation in Tape Drive Track Following Using Multiple Accelerometers,
  Proc. 6th IFAC Symposium on Mechatronic Systems, 506-510, 2013.
2. A. Pantazi, G. Cherubini, J. Jelitto,
  Skew Estimation and Feed-Forward Control in Flangeless Tape Drives,
  Proc. 6th IFAC Symposium on Mechatronic Systems, 484-489, 2013.
3. S. Furrer, H.E. Rothuizen, J. Engelen and M.A. Lantz,
  Side-Reading Effects in High-Track-Density Tape Recording,
  12th Joint MMM-Intermag Conference, 2013.
4. P.-O, Jubert, H.E. Rothuizen and M.A. Lantz,
  Effect of the Dimensions of a Stepped-Pole Writer on Side Erasure and Recording Performance,
  12th Joint MMM-Intermag Conference, 2013.
5. V. Venkatesan,
  Storage Aspects of the DOME Project,
  Presentation slides, 2013.
6. K. Tsuruta, A. Pantazi, G. Cherubini, J. Jelitto,
  Skew Estimation and Compensation in Tape Drives with Flangeless Rollers,
  Proc. 23rd ASME Annual Conf. on Information Storage & Processing Systems “ISPS 2013”.
7. G. Cherubini, A. Pantazi, J. Jelitto,
  Characterization and Simulation of MIMO Transport Systems in Tape Drives,
  Proc. 23rd ASME Annual Conf. on Information Storage & Processing Systems “ISPS 2013”.
8. G. Cherubini, A. Pantazi, J. Jelitto,
  Identification of MIMO Transport Systems in Tape Drives,
  Proc. 2013 IEEE/ASME Int’l Conf. on Advanced Intelligent Mechatronics “AIM 2013,” 597-602, 2013.
9. J. Engelen, S. Furrer, H. Rothuizen, M.A. Lantz,
  Flat-Profile Tape-Head Friction and Magnetic Spacing,
  Digest of IEEE 24th Magnetic Recording Conference, 2013.
10. S. Furrer, H.E. Rothuizen, J.B.C. Engelen, M.A. Lantz,
  Side-Reading Effects in High-Track-Density Tape Recording,
  IEEE Trans. Magnetics 49(7), 3706-3709, 2013.
11. P.-O. Jubert, H.E. Rothuizen, M.A. Lantz,
  Effect of the Dimensions of a Stepped-Pole Writer on Side Erasure and Recording Performance,
  IEEE Trans. Magnetics 49(7), 3733-3736, 2013.
12. A. Pantazi and M. Lantz,
  Vibration Compensation in Tape Drive Track Following Using Multiple Accelerometers,
  Proc. 6th IFAC Symposium on Mechatronic Systems, 506-510, 2013.
13. V. Venkatesan and I. Iliadis,
  Effect of Codeword Placement on the Reliability of Erasure Coded Data Storage Systems,
  Proc. 10th Int’l Conference on Quantitative Evaluation of Systems (QEST), Springer, LNCS 8054, 241-257, 2013.
14. V. Venkatesan and I. Iliadis,
  Effect of Latent Errors on the Reliability of Data Storage Systems,
  Proc. IEEE 21st Int’l Symposium on Modeling, Analysis, Simulation of Computer and Telecommunication Systems (MASCOTS), 293-297, 2013.
2012
1. A. Pantazi, J. Jelitto, N. Bui, E. Eleftheriou,
  Track-Following in Tape Storage: Lateral Tape Motion and Control,
  Mechatronics 22(3), 361–367, 2012.
2. G. Cherubini, C.C. Chung, W.C. Messner, R. Moheimani,
  Control Methods in Data-Storage Systems,
  IEEE Transactions on Control Systems Technology 20(2), 296-322, 2012.
3. E. Eleftheriou,
  Nanopositioning for Storage Applications,
  Annual Reviews in Control 36(2), 244-254, 2012.
4. J.B.C. Engelen, S. Furrer, H.E. Rothuizen, R.G. Biskeborn, P. Herget, C. Lo, M.A. Lantz,
  Planar Thin-Film Servo Write Head for Magnetic Tape Recording,
  IEEE Trans. Magnetics 48(11), 3539-3542, 2012.
5. S. Furrer, P. Jubert, G. Cherubini, R.D. Cideciyan, M.A. Lantz,
  Analytical Expressions for the Readback Signal of Timing-Based Servo Schemes,
  IEEE Trans. Magnetics 48(11), 4578-4581, 2012.
6. P.-O. Jubert, E. Delenia, J. Frommer, H. Rothuizen, M. A. Lantz,
  A Stepped-Pole Writer Geometry to Minimize Side Erasure on Barium Ferrite Tape,
  Digest of Intermag 2012, Vancouver, Canada, EC-06, 2012.
7. M.A. Lantz, G. Cherubini, A. Pantazi, J. Jelitto,
  Servo-Pattern Design and Track-Following Control for Nanometer Head Positioning on Flexible Tape Media,
  IEEE Transactions on Control Systems Technology 20(2), 369-381, 2012.
8. G. Cherubini, J. Jelitto, K. Tsuruta,
  Fast Servo Signal Acquisition in Tape Drives Using Servo and Data Channels,
  Mechatronics 22(3), 349-360, 2012.
9. G. Cherubini, J. Jelitto, K. Tsuruta,
  High-Precision Skew Estimation in Flangeless Tape Drive Systems by Dual Synchronous Servo Channel,
  Proc. 2012 ASME-ISPS / JSME-IIP Joint Int’l Conf. on Micromechatronics for Information and Precision Equipment “MIPE2012,” 370-372, 2012.
10. G. Cherubini, J. Jelitto,
  High-Performance Servo Channel for Nanometer Head Positioning in Tape Systems,
  Proc. 2012 IEEE/ASME Int’l Conf. on Advanced Intelligent Mechatronics “AIM 2012,” 788-795, 2012.
11. P.C. Broekema, A.-J. Boonstra, V. Caparros Cabezas, T. Engbersen, H. Holties, J. Jelitto, R. Luijten, P. Maat, R.V. van Nieuwpoort, R. Nijboer, J.W. Romein, B.J. Offrein,
  DOME: Towards the ASTRON & IBM Center for ExaScale Technology,
  Proc. 2012 Workshop on High-Performance Computing for Astronomy “AstroHPC,” 2012.
12. G. Cherubini, J. Jelitto, A. Pantazi,
  Initial Resolution of Head Position and Skew Uncertainty in Control Systems for Flangeless Tape Drives,
  51st IEEE Conference on Decision and Control, 5052-5058, 2012.
13. V. Venkatesan, I. Iliadis,
  A General Reliability Model for Data Storage Systems,
  International Conference on Quantitative Evaluation of Systems (QEST), 2012.
14. V. Venkatesan, I. Iliadis, R. Haas,
  Reliability of Data Storage Systems under Network Rebuild Bandwidth Constraints,
  IEEE International Symposium on Modeling, Analysis, Simulation of Computer and Telecommunication Systems (MASCOTS), 2012.

2011
1. M. A. Lantz, A. Pantazi, G. Cherubini, J. Jelitto,
  Nanoscale Track-follow Performance for Flexible Tape Media,
  Proceedings of 18th IFAC World Congress, 2011.
2. G. Cherubini, R.D. Cideciyan, L. Dellmann, E. Eleftheriou, W. Haeberle, J. Jelitto, V. Kartik, M. A. Lantz, S. Oelcer, A. Pantazi, H. Rothuizen, D. Berman, W. Imaino, P.-O. Jubert, G. McClelland, P. Koeppe, K. Tsuruta, T. Harasawa, Y. Murata, A. Musha, H. Noguchi, H. Ohtsu, O. Shimizu, R. Suzuki,
  29.5 Gb/in² Recording Areal Density on Barium Ferrite Tape,
  IEEE Transactions on Magnetics 47(1), 137-147, 2011.
3. V. Kartik, A. Pantazi, M. A. Lantz,
  Track-Following High Frequency Lateral Motion of Flexible Magnetic Media With Sub-100nm Position Error,
  IEEE Transactions on Magnetics 47(7), 1868-1873, 2011.
4. G. Cherubini, J. Jelitto,
  LPOS Symbol Detection by Soft-Output Combining of Dual Synchronous Servo Channels in Tape Drives,
  Microsystem Technologies 17(5-7), 857-862, 2011.
5. K. Tsuruta, N. Bui, G. Cherubini, J. Jelitto, A. Pantazi,
  Head Positioning with Flangeless Guide Rollers in Tape Drives,
  Proc. 21st ASME Annual Conf. on Information Storage & Processing Systems 2011 “ISPS 2011,” 279-281, 2011.
6. R.D. Cideciyan, E.S. Eleftheriou, G.A. Jaquette, P.J. Seger,
  Robust Embedding of Longitudinal Position into Tape Servo Signals,
  Microsystem Technologies 17(5-7), 831-839, 2011.
7. K. Tsuruta, N. Bui, G. Cherubini, J. Jelitto, A. Pantazi,
  Head Positioning with Flangeless Guide Rollers in Tape Drives,
  Proc. 21st ASME Annual Conference on Information Storage and Processing Systems “ISPS 2011,” 279–281, 2011.
8. S. Ölçer and R. Hutchins
  NPML Detection Employing IIR Noise-Prediction with Application to Magnetic Tape Storage,
  Technical Digest, IEEE Int’l Magnetics Conf. “Intermag, 2011” DE-05, 2011.
9. I. Iliadis, R. Haas, X.-Y. Hu, E. Eleftheriou
  Disk Scrubbing Versus Intra-disk Redundancy for RAID Storage Systems,
  ACM Transactions on Storage 7(2), 2011.
10. V. Venkatesan, I. Iliadis, C. Fragouli, R. Urbanke,
  Reliability of Clustered vs. Declustered Replica Placement in Data Storage Systems,
  Proc. 2011 IEEE 19th Int’l Symp. on Modeling, Analysis and Simulation of Computer and Telecommunication Systems “MASCOTS 2011,” 307-317, 2011. Winner of Best Paper award.
2010
1. V. Kartik, A. Pantazi, M.A. Lantz,
  Track-Following High Frequency Lateral Motion of Flexible Media,
  IEEE Digest of the Asia Pacific Magnetic Recording Conf. “APMRC 2010,” 2010.
2. E. Eleftheriou, R. Haas, J. Jelitto, M. A. Lantz,
  Trends in Storage Technologies,
  IEEE Data Eng. Bull. 4-13, 2010.
3. J. Jelitto, M. A. Lantz, E. Eleftheriou,
  Magnetic Tape Storage and the Growth of Archival Data,
  ERCIM News 80(1), 29-30, 2010.
4. G. Cherubini, R.D. Cideciyan, L. Dellmann, E. Eleftheriou, W. Haeberle, J. Jelitto, V. Kartik, M. A. Lantz, S. Ölçer, A. Pantazi, H. Rothuizen, D. Berman, W. Imaino, P.-O. Jubert, G. McClelland, P. Koeppe, K. Tsuruta, T. Harasawa, Y. Murata, A. Musha, H. Noguchi, H. Ohtsu, O. Shimizu, R. Suzuki,
  29.5 Gb/in² Recording Areal Density on Barium Ferrite Tape,
  Digest of Magnetic Recording Conf. “TMRC,” 29-30, 2010.
5. V. Kartik, A. Pantazi, M.A. Lantz,
  High Bandwidth Track Following for Moving Media,
  Proc. 20th ASME Annual Conf. on Information Storage & Processing Systems “ISPS 2010,” 265-267, 2010.
  (Best Paper Award of ASME ISPS-2010 “Flexible Media Mechanics and Tape Storage” Technical Track).
6. A. Pantazi, M. A. Lantz, W. Haeberle, W. Imaino, J. Jelitto, E. Eleftheriou,
  Active Tape Guiding,
  Proc. 20th ASME Annual Conf. on Information Storage & Processing Systems 2010 “ISPS 2010,” 304-306, 2010.
7. G. Cherubini, J. Jelitto,
  LPOS Symbol Detection by Soft-Output Combining of Dual Synchronous Servo Channels in Tape Drives,
  Proc. 20th ASME Annual Conf. on Information Storage & Processing Systems 2010 “ISPS 2010,” 31-33, 2010.
8. A. Pantazi, J. Jelitto, N. Bui, E. Eleftheriou,
  Track-Follow Control for Tape Storage,
  Proc. 5th IFAC Symposium on Mechatronic Systems, 532-537, 2010.
9. G. Cherubini, J. Jelitto,
  Fast Servo Signal Acquisition in Tape Drives,
  Proc. 5th IFAC Symposium on Mechatronic Systems, 538-544, 2010.
10. E. Eleftheriou, S. Ölçer, R.A. Hutchins,
  Adaptive Noise-Predictive Maximum-Likelihood (NPML) Data Detection for Magnetic Tape Storage Systems,
  IBM J. Res. Develop. 54(2), 2010.
11. T. Harasawa, R. Suzuki, O. Shimizu, S. Ölçer, E. Eleftheriou,
  Barium Ferrite Particulate Media for High-Recording-Density Tape Storage Systems,
  IEEE Trans. Magnetics 46(6), 1894-1897, 2010.
12. R. Cideciyan, E. Eleftheriou, G. Jaquette, P. Seger,
  Robust Embedding of Longitudinal Position into Tape Servo Signals,
  Proceedings of the 20th ASME Annual Conf. on Information Storage & Processing Systems 2010 “ISPS,” 262-264, 2010.
13. J. Jelitto, M. Lantz, D. Pease, E. Childers, E. Eleftheriou,
  Magnetic Tape Storage Advances and the Growth of Archival Data,
  1st Int’l Workshop on Standards and Technologies in Multimedia Archives and Records “STAR,” 2010.
14. T. Harasawa, R. Suzuki, O. Shimizu, S. Ölçer, E. Eleftheriou,
  Barium-Ferrite Particulate Media for High-Recording-Density Tape Storage Systems,
  11th Joint MMM-Intermag Conf., Paper AD-14, 2010.
15. V. Venkatesan, I. Iliadis, X.-Y. Hu, R. Haas, C. Fragouli,
  Effect of Replica Placement on the Reliability of Large-Scale Data Storage Systems,
  Proc. IEEE Int’l Symp. on Modeling, Analysis and Simulation of Computer and Telecommunication Systems “MASCOTS 2010,” 79-88, 2010.
2009
1. G. Cherubini, R.D. Cideciyan, E. Eleftheriou, J. Jelitto,
  Characterization and Detection of PPM-Encoded Servo Signals in Tape Drives,
  IEEE Pacific Rim Conference PacRim on Computers and Signal Processing, 2009.
2. V. Kartik, M.A. Lantz, E. Eleftheriou,
  Piezo-Electrically Actuated High Band Width Vibration Compensation for Moving Media,
  JSME-IIP/ASME-ISPS Joint Conference on Micromechatronics for Information and Precision Equipment, 2009.
3. S. Ölçer, E. Eleftheriou, R. Hutchins, N. Noguchi, M. Asai, H. Takano,
  Performance of Advanced Data-Detection Schemes on Barium-Ferrite Particulate Media,
  IEEE Trans. on Magnetics 45(10), 3765-3768, 2009.
4. S. Ölçer, E. Eleftheriou, R. Hutchins, N. Noguchi, M. Asai, H. Takano,
  Performance of Advanced Data-Detection Schemes on Barium-Ferrite Particulate Media,
  Digest of IEEE Int’l Magnetics Conf. “Intermag 2009,” 2009.
5. T. Mittelholzer,
  Enumerative Maximum-Transition-Run Codes,
  Proc. IEEE Int’l Symp. on Information Theory “ISIT 2009,” 1549-1553, 2009.
6. T. Mittelholzer,
  Enumerative Encoding of Maximum-Transition-Run Codes,
  Proc. 10th Int’l Symp. on Communication Theory and Applications “ISCTA ’09,” 2009.
7. S. Ölçer, V. Venkatesan,
  On the Characterization of Write-Equalized Magnetic Recording Channels,
  Digest of IEEE Int’l Magnetics Conf. “Intermag 2009,” 2009.
8. G. Cherubini, R. D. Cideciyan, E. Eleftheriou, J. Jelitto,
  Frame Synchronization for PPM-encoded Longitudinal Position Words in Magnetic Tape Storage,
  Proc. IEEE Globecom, 2009.
9. S. Ölçer, E. Eleftheriou, R. Hutchins,
  Compensation of PLL Loop Delay in Read Channels for Tape Storage Systems,
  Proc. IEEE Globecom, 2009.
10. G. Cherubini, J. Jelitto, E. Eleftheriou,
  MIMO Control Aspects for Mechatronic Systems with Application to Tape Drives,
  Workshop on Dynamics and Control of Micro and Nanoscale Systems, 2009 (Foils on conf. website).
11. S. Ölçer, E. Eleftheriou, R. Hutchins,
  Compensation of PLL Loop Delay in Read Channels for Tape Storage Systems,
  Proc. IEEE Globecom, 2009.
12. I. Iliadis,
  Reliability Modeling of RAID Storage Systems with Latent Errors,
  Proc. 17th Annual Meeting of the IEEE/ACM Int’l Symp. on Modelling, Analysis and Simulation of Computer and Telecommunication Systems “MASCOTS 2009,” 111-122, 2009.
2008
1. A. Argumedo, D. Berman, R. Biskeborn, G. Cherubini, R. Cideciyan, E. Eleftheriou, W. Häberle, D. Hellman, W. Imaino, J. Jelitto, K. Judd, P.-O. Jubert, M.A. Lantz, G.M. McClelland, T. Mittelholzer, S. Narayan, S. Ölçer,
  Scaling Tape-Recording Areal Densities to 100 Gbit/in²,
  IBM J. Res. Develop. (Storage Technologies and Systems), 52(4/5), 2008.
2. G. Cherubini, R.D. Cideciyan, E. Eleftheriou, P.V. Koeppe,
  Characterization of Timing Based Servo Signals,
  Digest of IEEE Int’l Magnetics Conf. “Intermag 2008,” 600-601, 2008.
3. T. Mittelholzer, E. Eleftheriou
  Reverse Concatenation for Concatenated Codes,
  Proc. IEEE Int’l. Conf. on Communications “ICC ’08,” 1991-1995, 2008.
4. S. Ölçer, J. Jelitto, R.A. Hutchins,
  Global Timing Control with Applications to Tape Storage Channels,
  IEEE Global Telecommunications Conference “Globecom,” 2008.
5. S. Ölçer, J. Jelitto, R.A. Hutchins,
  Global Timing Control for Tape Storage Channels,
  Digest of IEEE Int’l Magnetics Conf. “Intermag 2008”, 1519-1520, 2008.
6. A. Dholakia, E. Eleftheriou, X.-Y. Hu, I. Iliadis, J. Menon, K.K. Rao,
  A New Intra-disk Redundancy Scheme for High-Reliability RAID Storage Systems in the Presence of Unrecoverable Errors,
  ACM Trans. Storage 4(1), 1-42, 2008.
7. I. Iliadis, R. Haas, X.-Y. Hu, E. Eleftheriou,
  Disk Scrubbing versus Intra-disk Redundancy for High-reliability RAID Storage Systems,
  ACM SIGMETRICS 2008.
8. I. Iliadis, X.-Y. Hu,
  Reliability Assurance of RAID Storage Systems for a Wide Range of Latent Sector Errors,
  IEEE Int’l Conference on Networking, Architecture and Storage, 2008.
2007
1. G. Cherubini, E. Eleftheriou, J. Jelitto, R. Hutchins,
  Synchronous Servo Channel Design for Tape Drive Systems,
  Proc. 17th ASME Annual Conf. on Information Storage and Processing Systems “ISPS 2007,” 160-162, 2007.
2006
1. S. Ölçer, R. Hutchins,
  Cancellation of MR Head Asymmetry in Magnetic Tape Storage Systems,
  Proc. IEEE Globecom, 2006.
2. S. Ölçer, E. Eleftheriou, R.A. Hutchins,
  Cyclic Equalization and Channel Identification for Magnetic Tape Recording Systems Using the Data Set Separator,
  IEEE Trans. on Magnetics 42(10), 2582-2584, 2006.
3. A. Dholakia, E. Eleftheriou, X.-Y. Hu, I. Iliadis, J. Menon, K.K. Rao,
  Analysis of a new Intra-Disk Redundancy Scheme for High-Reliability RAID Storage Systems in the Presence of Unrecoverable Errors,
  ACM SIGMETRICS 2006.