The straight skinny on disk vs. tape pricing; tip: you may be surprised.For years, tape was considered to be less expensive than disk storage. But after years of disk-price erosion, the perception that disk costs less than tape became more widespread. Determining the price of various storage subsystems The part of a computer system that provides the storage. It includes the controller and disk drives. See storage system. has been subject to considerable misinterpretation, and meaningful pricing comparisons for tape and disk storage are scarce. For example, look at typical published average selling prices The average sales price of goods or commodities. Especially used in the retail sector and technology distribution. for various disk and tape subsystem A unit or device that is part of a larger system. For example, a disk subsystem is a part of a computer system. A bus is a part of the computer. A subsystem usually refers to hardware, but it may be used to describe software. components: * 73GB Ultra SCSI The designation for various high-speed SCSI interfaces. The original specification was Ultra SCSI, followed by Ultra2, Ultra3, etc. For details, see SCSI. hard drive: $861 (unit price), $11.82 (ASP asp, popular name for several species of viper, one of which, the European asp (Vipera aspis), is native to S Europe. It is also a name for the Egyptian cobra (Naja haja). $/GB) * 181.6GB Ultra SCSI3 hard drive: $1,671 (unit price), $9.20 (ASP$/GB) * 80GB Ultra ATA An enhanced version of the IDE interface that transfers data at 33, 66 or 100 Mbytes/sec. These enhancements are also called "Ultra DMA," "UDMA," "ATA-33," "ATA-66," "ATA-100," "DMA-33," "DMA-66" and "DMA-100." See IDE for all the ATA types and speeds. 100: $250 (unit price), $1.56 (ASP$/GB) * 40GB Ultra ATA 100: $68 (unit price), $1.70 (ASP$/GB) * SDLT (Super DLT) See DLT. Ultra SCSI tape drive: $5,800 (unit price), $26.36 (ASP$/GB) * LTO (Linear Tape Open) A family of open magnetic tape standards developed by HP, IBM and Quantum (formerly the Certance subsidiary of Seagate) that are licensed to third-party vendors. LTO cartridges contain a memory that stores historical usage data. Ultra SCSI tape drive: $5,300 (unit price), $26.50 (ASP$/GB) * SDLT cartridge (1) See phono cartridge. (2) A removable storage module that contains magnetic disks, optical discs, magnetic tape or memory chips. Cartridges are inserted into slots in the drive, printer or computer. (220GB compressed): $129 (unit price), 59 cents (ASP$/GB) * LTO cartridge (200GB compressed): $115 (unit price), 58 cents (ASP$/GB) * Tape Library *: $33,000 -- $67,500 (unit price), $4.50-$1 .25 (ASP$/GB) Note: ASP levels as of mid-September 2002 from storage VAR and online vendors including U.S. and international figures. Pricing levels may vary. * Prices used are for a variety of tape libraries ranging from 80 to 680-cartridge slot capacity. Disk Pricing Considerations Unfortunately, lists like the one above appear frequently and are often misinterpreted. The price of tape storage per gigabyte One billion bytes. Also GB, Gbyte and G-byte. See giga and space/time. (unit) gigabyte - 2^30 = 1,073,741,824 bytes = 1024 megabytes. Roughly the amount of data required to encode a human gene sequence (including all the redundant codons). See prefix. appears higher than the price of disk storage because the price per gigabyte of disk drives is lower than the price per gigabyte of tape drives. Adding the price of tape media only adds more to the tape price. For example, the prices of disk drives are indeed below the prices of tape drives and media, but these are not valid comparisons and do not represent the price of a working subsystem for either disk or tape. All too often, pricing comparisons are incorrectly made between the price of a disk drive and a tape drive. These do not represent real-life examples, however. The disk drive cannot function without a controller and the controller price uplifts the ASP of disk storage considerably-- typically adding five to 10 times the hard drive per gigabyte price. Therefore, disk pricing must be determined for a working and functional disk subsystem that includes the controller and hard d isk drives rather than just a single component of the subsystem. To compare tape and disk pricing accurately, the prices for working subsystems must be used. Pricing for a workable disk subsystem falls into three distinct categories: * Enterprise disk market: FC, SCSI SCSI in full Small Computer System Interface Once common standard for connecting peripheral devices (disks, modems, printers, etc.) to small and medium-sized computers. SCSI has given way to faster standards, such as Firewire and USB. ; $70-$90 (ASP $/GB range for working disk subsystem) * Mid-range disk market: SCSI, FC; $30-$40 (ASP $/GB range for working disk subsystem) * Low-end "Ghetto RAID": IDE (1) (Integrated Development Environment) A set of programs run from a single user interface. For example, programming languages often include a text editor, compiler and debugger, which are all activated and function from a common menu. ; $l0-$15 The price per gigabyte of the disk drive is actually a relatively small component of a workable disk subsystem price per gigabyte. Tape Pricing Considerations For tape pricing, no business normally operates a tape subsystem with just one tape drive and one tape cartridge See cartridge. . The most common tape environments will have an automated au·to·mate v. au·to·mat·ed, au·to·mat·ing, au·to·mates v.tr. 1. To convert to automatic operation: automate a factory. 2. tape library containing several tape drives and several tape cartridges. The price of the associated tape library, tape drives and media contained in the library must be used to give a comparable (apples-to-apples) price comparison to disk prices. This then provides a comparison of working disk subsystems and tape subsystems, not just comparisons of the individual components. Comparing the price of a tape drive to the price of a hard disk drive is not a meaningful comparison. * Enterprise tape library market: FC, SCSI; $1.2525 cents (ASP $/GB range for working disk subsystem) * Mid-range tape library market: SCSI, FC; $4.50$1.25 (ASP $/GB range for working disk subsystem) * Low-end market In the USA, as well as in most developed countries, the low-end market consists of lower-priced products suitable for customers who are not willing or able to spend large amounts of money. In developing countries, some low-end products may be considered high-end or even luxury items. : SCSI, IDE; $l0-$ 15; NA, manual mount and autoloader The key factor used to determine the purchase price per gigabyte for a working tape subsystem is the ratio of the number of tape cartridges to the number of tape drives. The price of tape decreases as the ratio of cartridges
To illustrate this key factor for tape pricing, for example, consider the following configuration. The smallest capacity library used in this study contained 80 cartridge slots and two SDLT tape drives yielding a capacity of 16TB at 200GB compressed per cartridge. The cartridge-to-drive ratio is 40. For pricing, the 80-slot library was priced at $33,375, two tape SDLT drives at $5,800 each and 80 100GB native capacity cartridges at $120 each. Total: $53,975 or $3.37 per gigabyte. By comparison, 16TB of disk storage will cost approximately $200,000 for IDE/ATA; $560,000 for mid-range disk; and $1.28 million for enterprise disk using the midpoints of each price range. Subsequent analysis may vary by changing the number of drives and cartridges. Non-automated (offline) tape storage is not included in the study. Any cartridge-per-drive ratio is meaningless and there is no actual way to determine a price per gigabyte other than spreading the capacity of all of the tape cartridges onsite and offsite across all of the tape drives. Please note: Obviously, because there is no tape library cost, a manual tape environment will have a lower hardware price than an automated tape environment. Without automation, however, the manual labor or human effort and/or the associated TCO (1) (Total Cost of Ownership) The cost of using a computer. It includes the cost of the hardware, software and upgrades as well as the cost of the inhouse staff and/or consultants that provide training and technical support. See ROI. (total cost of ownership) expenses to manage the tape environment go up considerably. Therefore, for the purposes of this article, only an automated tape environment is used. Typical tape libraries used in non-mainframe systems can attach from four to 20 tape drives and contain from 80 to 700 tape cartridges. The price per gigabyte of tape diverges from the price per gigabyte of disk as the ratio of cartridges to drives increases. This sliding scale slid·ing scale n. A scale in which indicated prices, taxes, or wages vary in accordance with another factor, as wages with the cost-of-living index or medical charges with a patient's income. is the key to understanding tape pricing dynamics. To correctly determine tape pricing use: * Price of a tape library. * Price of the tape drives. * Price of the media inside the library. * Total capacity of the library based on 2x (tape compression factor) or twice the native capacity of each cartridge times the number of cartridges. * Divide the total price of the library, drives and media by the capacity (in gigabytes) of the tape library to determine the price per gigabyte for the working tape subsystem. The average ratio of cartridges to drives in an automated tape library can range from 20-to-1 to 80-to-1 with 15-to-1 to 40-to-1 being the most common range. Increasing the number of tape drives attached to a library without adding additional cartridge capacity adds to the price and raises the price per gigabyte. Increasing the capacity of a tape library without adding drives lowers the price per gigabyte. For typical Unix, Win2K, and other mid-range automated tape configurations, the price per gigabyte of an automated tape subsystem ranges from one-fifth to over one-twentieth the price of an equivalent amount of disk storage. In mainframe (OS/390 and z/OS) tape storage environments, the ratio of tape cartridges to tape drives in an automated library often exceeds 200 and pricing can be less than one-thirtieth the price per gigabyte of disk. Changing the storage subsystem configuration for disk and for tape can alter the pricing and performance levels. Adding more tape drives raises the price per gigabyte, bu t also increases the throughput capability of the automated tape subsystem. Adding more disk drives to a disk subsystem without adding more data transfer capability may increase capacity, but lower throughput and response times given the increased workload. This is a complex and dynamic subject and every attempt has been made to create a meaningful and realistic comparison between disk subsystem and tape subsystem pricing. Therefore, for usable USable is a special idea contest to transfer US American ideas into practice in Germany. USable is initiated by the German Körber-Stiftung (foundation Körber). It is doted with 150,000 Euro and awarded every two years. or working subsystems, tape pricing is less expensive than disk pricing and it becomes increasingly less expensive as the cartridge-to-drive ratio increases. |
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