Storage Technologies in the Wings

Information is always piling up fast. The question is how to store and restore it. We look at some technologies that will let all those candies fit into an ant's stomach

Sunday, July 16, 2006

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Once upon a time, the organizations had plenty of time and capacity or face it that the needs were limited. Backups could be done at night when the systems were not loaded or were shut down. But since then, the needs have crossed the roof, systems work around the clock and so do the users, and there's no period when you can shut everything down for backup. Today, an organization needs to store all kinds of data. There are different time periods for which you want to store this data based on its utility to the organization and regulatory needs. And then you have storage devices lying around that've been exhausted or are soon going to be all filled up.

All this makes it necessary that there be better storage devices that are more capacious and faster. For this, researchers have been continuously exploring new technologies or improving existing ones to help you store a larger amount of data, for a longer period of time. And all this in a manner that you do not have to pay exhorbitantly compared to what you do today. The new technologies should be such that you have to do minimum change in the existing infrastructure. Some of these include virtual tapes, 4GFC, Blu-ray, HD DVD, serverless backup, perpendicular recording, PSAN, 3D and online storage that are standing the wings to join the bandwagon.We take you through the technology behind each and promises they make for the future.

Perpendicular recording

Let us get down to the basics. More things can be packed in a space when they stand up rather than when they are lying down. And that's the reason why perpendicular recording is in vogue. Perpendicular recording aligns the bits perpendicular to the disk, which allows you to fit in more data into the same space, at higher recording densities. This technology is expected to increase the capacity of hard drives as much as 10 times. It is the saturation in the longitudinal recording capacities that has led to this innovation to counter superparamagnetism. Superpara-magnetism is a phenomenon that causes interference amongst the magnetic grains that make up data bits when they are packed beyond a certain density on the disk. As a result, the grains lose their orientation leading to corruption of data on the storage device. Seagate has been the pioneer in using this technology by launching its 2.5 inch, 160 GB drive for notebooks. The latest we've received for evaluation is the Seagate Barracuda drive with a whopping 750 GB capacity. Hitachi is also backing this technology. At this speed, we will soon have 3.5 inch disks storing terabytes of data.

Virtual tape library
Tape has always been the preferred medium of backing up data permanently and its benefits have been numerous. For instance, with tape you get to store data off-site for a longer period of time that you might need it for. Not only that you can restore all data lost or deleted from the machines in use. This is contrary to how the hard-drive storage works. Here the data stored, used as well as unused, all lies on the machine you are using. While this simplifies the way you can access the data (tape stores the data sequentially while the disk does it in random fashion), it is a costlier option compared to the tape-based storage, both in long as well as short run.

But that's only one side of the coin. Disk-based storage hasn't lost the battle for the advantages it has over tapes. It is faster, and is easier to handle when you want to work with and restore data. To add to it, disks offer online storage unlike tapes that need to be kept separately once the data is backed up on them.

In the light of advantages and disadvantages that each one has, researchers had been struggling to find out a workaround. And they have succeeded in having the cake and eating it too-with virtual tapes. Virtual tapes combine the power of both the tapes and disks, in a manner that lets you reap the benefits of both. Virtual tapes emulate (behave, look and feel) like a tape, though they are actually disks. In action, the back-up software sees the VTLs (Virtual Tape Libraries) as physical tape libraries to perform backup operations. As a result, while the data is written in a sequential format (as in tapes) on the disks that emulate as tapes, it is backed up almost 10 or more times faster than the real tape. Also, you are saved from the hassles of rotating, handling and storing tapes.

It requires almost negligible or no changes to the back-up processes, schedules and workflows. While it still doesn't solve the inherent problems of storing the data offsite to be used in case a disaster strikes, VTLs can be used as faster alternatives to store less-used data that can finally be moved to real tapes whenever needed.

FC and iSCSI
iSCSI, for a long time, was perceived as a better, low-cost storage networking protocol compared to the Fiber Channel. But today iSCSI has emerged as an entry level for SAN interface. On the other hand, the FC (Fiber Channel) is apt for operations that involve connecting servers to shared storage devices. Most iSCSI based storage area networks use 1 GB Ethernet unlike the FC that has touched 4G capabilities. The 4GFC products are well suited for high-bandwidth applications such as voluminous data backups, streaming media and transactional processing.
Either technology is well suitd for specific needs. To understand this, if a less amount of data is to be processed, both technologies serve the purpose (but FC loses out to iSCSI due to its price and difficult deployment process here). On the other hand, if more data is to be handled, iSCSI's speeds create bottlenecks.

Serverless backup

When a backup is in progress, your servers-the source and the backup servers-are the most stressed. During this time they consume a significant amount of CPU cycles and memory. The solution A good option is to offload these servers of this extra load during backups. The process is referred to as serverless backup, and is a SAN based solution. This is done when you use a data-mover device that initializes the back-up process to copy the data directly from the source (say, a hard disk) to the destination device (back-up devices). The data mover may be implemented in a switch or a router. There are products available in the market that have the serverless back-up option that leverage SNIA's Extended SCSI Copy command to significantly enhance performance by taking the backup load off servers and freeing CPU time for other mission critical tasks. When to consider While there are such high-end backup solutions offered by companies like Legato, Veritas, Computer Associates and IBM, it is not always necessary that you have to switch to the new ways. Instead, your decision should be based on your priorities, peak hours and type of data that you need to back up. For instance, if you need to backup the mailboxes of all the employees across the organization, you need not do that in office hours when the servers are loaded with other processes. You may go for such solutions if your business needs include: Frequent backup and restoration of huge amounts of data Backup during office hours and, Your priority is server performance

3D storage
Imagine writing data across a volume of space rather than on a two-dimensional media. This means the same area can be used to store more data. This is the idea behind 3D storage. Here, you are not only using the x and y dimensions but also z-axis to store data.

A hologram is formed on a photo-sensitive recording media at a place where the reference beam and the signal beam carrying data intersect. Holography has the potential for fast transfer rates and fast random access times. This is because the data are stored and recovered in parallel-typically 1 million bits at a time.

Experts predict that in a few years we'll eventually be able to store terabytes of information in a space no larger than several CDs stacked on top of each other. That's the promise of holographic storage. For more on how it works, refer to Enterprise Storage Technologies: the way ahead, in our March 2006 issue.

HD DVD vs Blu-ray
While the debate on which one will take the market by storm is quite old now, it is still hot. If it is only price that will govern who will dominate the market, then the verdict tilts in favor of HD DVDs. But if the battle is out for higher storage capacities, it will be Blu Rays' turn. Both HD DVDs (High Definition DVDs) and Blu Ray disks use shorter-wavelength blue laser to read and write data. The two are heavily backed by different industry giants.

Blu-ray is backed by Sony while HD DVD uses another technology called the iHD that Microsoft and Toshiba have worked on. A dual-layer HD DVD packs around 30 GB data on it as compared to the 50 GB (around one and a half times) by Blu rays, which is by no means small. We have to watch out for some time before judging which one wins.

P-SAN
Here is a disk-based backup storage technology with which you no longer need to use fiber-optic cabling to connect SAN components. P-SAN is a storage system developed by JMR Electronics with the capability to connect to the network as an extension of the standard PCI bus on personal computers. It uses a PCI switching architecture to work as an extension of the JMR's PCI bus using CA's BrightStor ArCserve backup solution. Instead of fiber-optic links, the technology makes use of IP storage. This means that it uses TCP/IP and standard Cat 5 cabling to connect to the network. It can scale up to large capacities at an optimum cost, making it a perfect alternative to tape or other costlier disk-based systems.

Online storage
This is an interesting option that organizations and individuals can explore alike and there are already more applications than you might first realize. There are sites that offer a ID/password protected space on the Internet where you can store your files. Your space can only be accessed by you or by someone you want to give access to. Today many such services like Foldershare, Bitvault, Xdrive and iBackup are already operative that give you both paid and free storage space online. While they give a small amount of storage space for free, say 25-50 MB, they have paid services for
organizations that would need larger storage space. Some sites offer true group collaborative functions as well. This way you can access your data from any computer if you have Internet access and a browser. Though individuals are currently using most of this online space to store data, organizations can also benefit from it once these sites integrate efficient security mechanisms within their services. Its not over yet. As demands on capacities continue to explode, new technologies will rise up.

Rinku Tyagi

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