Posts Tagged ‘hard disk drive’

Hard Disk Prices to Remain High Through 2014

February 14th, 2012 Comments off

While hard drive (Hard disk drive) supplies are beginning to resurge, inventories won’t be back to normal before the third quarter of the year and costs will stay abnormally high through 2014, according to researching the market firms IHS iSuppli and Coughlin Affiliates.

Consequently of flooding in Thailand this past year, Hard disk drive prices will probably increase 20% to 30% over their average pre-ton prices and turn into there through the majority of 2012, Coughlin Affiliates stated in the report today (download PDF).

Hard Disk Prices to Remain High Through 2014

Furthermore, the hard disk manufacturing industry may have to spend about $1 billion to replace and repair manufacturing plants broken through the monsoonal flooding.

Hard disk drive supplies within the 4th quarter of 2011 fell by 26% in comparison to exactly the same period this year, according to IHS iSuppli. Deliveries are positioned to decline by another 13% within the first quarter of 2012 by 5% within the second quarter with an annual basis.

The typical global value for HDDs jumped by 28% within the 4th quarter of 2011, according to IHS iSuppli. While prices will decline by 3% within the first quarter by 9% within the second quarter, they’ll remain inflated for the entire year.

“Prices will stay high for several reasons, such as the greater costs connected using the moving of production, in addition to greater component costs due to flooding impacts among component makers,” stated Fang Zhang, a storage analyst for IHS iSuppli.

PC prices may also be affected because system makers have signed annual contacts with Hard disk drive makers which have locked them into elevated prices deals for that relaxation of the season, Zhang noted.

Furthermore, industry Hard disk drive consolidation could hold prices greater than pre-ton levels for any couple of more quarters because you will find less rivals on the market, IHS iSuppli stated. It had been mentioning to mergers between Seagate and Samsung and between Western Digital and Hitachi GST.

Inside a report launched Friday, iSuppli predicted the Thailand flooding continues to have an affect on inventory and costs until deliveries rise first by 2% within the third quarter, then a 42% surge within the 4th quarter of 2012.

“The recovery of worldwide Hard disk drive manufacturing has started and can continue throughout each quarter of 2012, hard disk drive prices will stay inflated and inventories continues to be depleted, showing that demand is exceeding supply. Demand and supply should return to balance through the finish from the third quarter.” Zhang stated.

Coughlin Affiliates stated the mixture of industry consolidation and Thailand-related shortages, can lead to greater Hard disk drive prices a minimum of until 2014. The greater prices, however, can help fund costly new technology transitions by 2015 or 2016 and increase areal density growth rates by 40%.

The annual rate where hard drive areal densities increase has slowed down recently, Coughlin Affiliates stated.

However, drive capabilities continue to grow due to technology developments for example Warmth-Aided Magnetic Recording (HAMR). While hard disk areal density growth has slowed down, storage capabilities continue to rise: 3.5-in. HDDs with storage capabilities of 12TB and a pair of.5-in. HDDs with 6 B are required by 2016.

Due to reduced areal density growth, user companies may have to save money per gigabyte of drive capacity within the next 2 yrs. The typical hard disk capital equipment investing each year between 2008 and 2016 is believed at about 7.2% of hard disk industry revenue.

How does HDD store data?

April 10th, 2011 Comments off

How does HDD store data?Hard disk drives store data on one or more metal oxide platters. These platters spin at a rate of 3600-10,000 revolutions/minute, hold magnetic charges. A read-write head attached to an actuator arm actually floats on a cushion of air, 1-2 micro-inches (one millionth of an inch) above the surface of the platters. Data flows to and from these heads via electrical connections. Any force alters this process may cause data loss.

Ten years ago hard drives stored 40 Megabytes (MB) of data. Today’s hard drives store data up to 2000 gigabytes (GB) on a smaller surface. Increasing storage capacities amplify the impact of data loss. As more and more data is stored in smaller and denser areas, mechanical precision becomes crucial.

As a part of this advancing technology, the drive tolerance (distance between the read/write head and the platter where data is stored) is steadily decreasing. A slight nudge, an unstable power surge or a dust introduced into the drive may cause the head to touch the platter, resulting in a head crash, PCB burnt, bad sectors, etc. In some situations, the data residing in the area touched by the head may be permanently destroyed.

The current tolerance drives is 1-2 micro-inches (millionths of an inch). Comparatively, a speck of dust is 4-8 micro-inches and human hair 10 micro-inches. These sizes contaminants can cause serious data damage.

What Makes a Good Hard Disk Drive?

February 28th, 2011 Comments off

When looking to buy a hard drive there is a quick checklist of things to look for:

  1. Interface (PATA, SATA, SCSI or other more exotic setups)
  2. Capacity (how much space do you need/want)
  3. Spindle speed (i.e., 5400rpm, 10,000rpm, 15,000rpm etc)
  4. Cache (2MB, 8MB, 16MB)
  5. Brand (Western Digital, Seagate, Maxtor etc)

HDD Interface:

  • PATA drives are arguably the most universally compatible, are the cheapest and offer a respectable degree of performance however there is a potential inconvenience of having to set/adjust jumpers on the drive.
  • SATA (and SATA-II) drives are the next-generation drives and outperform similarly priced PATA drives (the price delta is usually no more than $10). Since there is only one drive per cable, no jumpers need to be set however the potential downside is that the destination motherboard/controller may not offer native boot-time support of the SATA drive (thus requiring a floppy/CD with the drivers in order to install an OS). Another consideration is if the drive only accepts SATA-power connectors than either the PSU needs these special connectors in order to power the drive (or adaptors must be purchased)
  • SCSI drives have the inconvenience of lack-of-boot-time support as well as the potential hassle of assigning SCSI id’s and performing termination. The upside is that many RAID options are available (much more so than with IDE drives) as well as significantly improved performance. Of the three common interfaces, SCSI is the most expensive.

HDD Capacity:
The old rule for determining how much drive space is requires is to “estimate how much you think you will need, double it and round-up to the nearest drive size”. With dropping drive prices as well as decreasing price deltas (i.e., going from a 120GB to 160GB drive is usually $10 — why? Because a 120GB drive is just a 160GB drive with a half-a-platter disabled).

HDD Spindle Speed & Cache:
Naturally, the faster the platters spin the better the overall performance however it is not always as simple as that. With SCSI drives, it’s fairly clean-cut as they tend to fall into distinct categories (10k and 15k rpm drives) with very distinct performance and price brackets. For IDE drives the three most common speeds are 5400, 7200 and 10000 rpm however the element of cache makes things interesting.

The argument for 5400rpm drives used to be “get a massive 5400rpm drive for archive — you’re not gonna be accessing it all the time so access-time performance isn’t critical” however with the advent of affordable (and massive) 7200rpm drives there isn’t much of a case for 5400rpm drives from a performance/functionality perspective (i.e., you won’t be able to get a 500GB DeskStar drive in a 5400rpm flavour). The only case really for 5400rpm (or slower) drives is for people looking to build uber-quiet systems. All 5400rpm IDE drives come with 2MB of cache.

Mainstream 7200rpm drives come in several flavours, 2MB, 8MB and 16MB of cache and with the wide variety of capacities. Buying a 2MB cache drive isn’t really a smart move anymore as the price delta to go from a 2MB to 8MB cached drive is usually ~$10. In the case of 16MB drives (currently only the Maxtor DiamondMax 10) which also offer NCQ support as well as being one of the few native SATA drives (Seagate’s barracuda 7200. 7 is another), it is obvious that the 16MB cache allow the DiamondMax10 to be the best performer for a 7200rpm drive and the NCQ and drive capacity allows for the drive to be immediately implemented in a server environment. Realistically the only competition in terms of performance for these drives are the 10k rpm drives.

Currently, two IDE drives support 10k rpm spindle speed (with 8MB of cache) and the advantages are obvious: significantly reduced access times. The downside is that (a) the drives are exceptionally expensive, (b) the highly competitive Maxtor 16MB cache drives represent a significantly improved value hands-down.

So will it be 10k@8MB ot 7.2k@16MB?
Ok let’s have a look at some numbers,

AVG Transfer rate
Maxtor DiamondMax 10 (NCQ on) — 54.5MB/s
Maxtor DiamondMax 10 (NCQ off) — 54.6MB/s
WD Raptor II — 64.9MB/s
with HDTach 3.0, it’s fairly evident that the Raptor is superior by a significant margin.

Burst Transfer
Maxtor DiamondMax 10 (NCQ on) — 131.7MB/s
Maxtor DiamondMax 10 (NCQ off) — 136.3MB/s
WD Raptor II — 118.7MB/s
here the tables are reversed however burst transfers are not as significant as average throughput.

Random Access Time
Maxtor DiamondMax 10 (NCQ on) — 13.9ms
Maxtor DiamondMax 10 (NCQ off) — 13.8ms
WD Raptor II — 7.9ms
The Raptor has a significantly reduced access time (42% advantage) however we don’t see anywhere near a 42% advantage in terms of benchmarked throughput performance … This is due to the larger cache count on the DiamondMax10: with the larger cache, the performance of the drive depends less and less on the mechanics of the drive (i.e., it reduces the effect of the rpm advantage the Raptors have)

Diskbench 2.3 – 250mb file
Maxtor DiamondMax 10 (NCQ on) — 16.2MB/s (30.7sec)
Maxtor DiamondMax 10 (NCQ off) — 15.3MB/s (33.6sec)
WD Raptor II — 13. 0MB/s (38. 2sec)
Here we can see the cache-advantage flex it’s muscles: a 17%-25% advantage in real-world performance (impressive if we consider the access-time disadvantage the Maxtors are operating with).

anandtech offers similar results with the Maxtor and wd trading spots back and forth with the 16MB Maxtor generally keeping up with or beating the 8MB Raptors (albeit by non-massive margins). Here is the 8MB Raptor pulling ahead by a non-insignificant margin


Summarizing the SYSmark scores, the Raptor comes out on top but with a very small lead


the Raptor pulls ahead with a small lead in UT2004 load times,


however the Raptor comes in last when multitasked heavy-disk access is thrown at it:


From a value perspective, there is almost no reason to recommend the WD 10k drives: one can get a 300GB Maxtor 16MB cache drive for the same price as a 74gb Raptor II. Now if the Raptor swept the floor it would probably be justifiable to purchase it however that was not the case. Perhaps if/when a 10k 16MB cache drive is released, the high-end drive market can be a bit more clear-cut.

HDD Brand:
Brand doesn’t matter all that much: people can tell you nightmare stores about Company X and recommend Company Y, however it’s probably equally possible to find nightmare stories about Company Y. While there may be bad drives (for instance the IBM/Hitatchi GXP75), it doesn’t mean that the entire product line will be bad.

Basic Knowledge of Hard Disk Drive: Definitions

February 28th, 2011 Comments off

Basic Knowledge of Hard Disk DriveIDE — This is simply an abbreviation for integrated-drive-electronics which is a physical attachment interface and is affiliated with the term ATA. It is often incorrectly used to describe a specific type of IDE/ATA interface known as Parallal-ATA (see PATA). See ATA.

EIDE — An extension of IDE, EIDE, or enhanced-IDE added to IDE support for larger drives (EIDE imposed a limit of 8.4GB, a vast improvement over the 528MB limit imposed by the original IDE design) as well as supporting faster throughput protocols. All modern hard drives whether labeled IDE or EIDE are in fact, EIDE devices.

ATA — An abbreviation for at attachment, (which fully expanded is advanced technology attachment). The ATA standard encompasses all aspects of interfacing with said devices: it defines physical, electrical, transport and command protocols for compliant devices. The ATA specification, introduced by the small form factor committee (SFF) is a 16bit interface which draws it’s roots from the ISA architecture.

Important: For the remainder of this guide, the term IDE will be used to define/describe the physical connections while the term ATA will be reserved for discussions revolving the electrical, transport and command protocols. Furthermore, EIDE and IDE drives will be grouped together under IDE and distinctions will be explicitly noted where required.

PATA — Parallel ATA, this refers to drives qualifying under the ATA specification (commonly this refers to non-SCSI drives) and make use of a 40-pin or 80-pin IDE connection. Also commonly (albeit vaguely/incorrectly referred to as “IDE”).

SATA — Serial ATA, this refers to drives qualifying under the ATA specification (again, essentially non-SCSI drives) and make use of a seven-pin (three ground, four signal) IDE connection. Native support for boot-time support of SATA drives is dependent on the chipset: if no support is available, boot-time drivers are required. SATA2 (aka SATA-II) is an extension of the serial ATA specification and allows for twice the throughput, connectors remain the same.

Important: For the remainder of this guide, the above terms/definitions PATA and SATA will be adhered to avoid ambiguity with the term “IDE”

PIO — Programmable I/O (input/output), this is a transfer/transport specification which falls under the larger definition of ATA. There are five different versions of PIO, Mode 0 though Mode 4 respectively. Original IDE (non-EIDE drives that is) only supported the first three modes of transfer (3.3MB/s, 5.2MB/s and 8.3MB/s respectively). The reason for this (the limited support) is because the interface was based on the ISA bus which had a limit of 8.3MB/s. Later EIDE drives added support for two more modes of transfer (11.1MB/s and 16.6MB/s respectively). Searching through Google you can find mention here and there of a last transfer specification, PIO Mode 5 which was supposed to support 22.2MB/s however it was not implemented due to the success of the DMA transfer specification. PIO is only supported on modern hardware as a fail-safe and/or troubleshooting transfer specification and should not be used in an active environment.

DMA — An acronym for direct memory access, this is often incorrectly taken to be synonymous with ATA when it is in fact a sub-component of the ATA specification (so it’s not too big a deal). There are six DMA transfer protocols: the first three are “Single-Word” and the latter are “Multi-Word” with the difference being the latter offering improved performance due to bursting operations. Single-Word modes 0-2 support transfer rates of 2.1MB/s, 4.2MB/s and 8.3MB/s respectively. Multi-Word Modes 0-2 support transfer rates of 4.2MB/s, 13.3MB/s and 16.7MB/s. On modern systems, Multi-Word Mode 2 is commonly used as the transfer specification for optical drives.

UDMA — An extension of DMA, ultra-DMA operates on the PCI bus (which, for consumer systems, provides 133MB/s of available bandwidth); one of the fundamental changes between UDMA and DMA is that, with UDMA, the device attempting to access memory negotiates with the memory-controller directly rather than via another controller card. The second fundamental change was that CRC was introduced to improve reliability. Strictly with respect to transfers, one can consider UDMA to be the “DDR-ed” version of DMA as commands were processed on both edges of the clock. UDMA supports seven (possibly eight) transfer modes. Mode 0 (16.7MB/s), Mode 1 (25.0MB/s), Mode 2 (33.3MB/s), Mode 3 (44.4MB/s), Mode 4 (66.7MB/s), Mode 5 (100.0MB/s), Mode 6 (133.0MB/s) and Mode 7 (150.0MB/s). Since I don’t have a SATA-II setup I can’t verify if SATA-II operates in Mode 8 (300.0MB/s) or not. Like DMA, UDMA is often incorrectly labeled as being synonymous with ATA however again, this is an insignificant error). All these advantages of UDMA require too much signal clarity to be supported by “DMA cables” (correctly called 40-pin IDE cables) and as such a grounding wire was added for each signal wire to improve signal quality (hence we have 80-pin IDE cables). A bit of searching suggests SATA-II will be encompassed under the ATA Mode 7 protocol.

Important: For the remainder of this guide, since DMA won’t be found on modern hard drives, any reference to “DMA” will actually be referring to UDMA.

SCSI — Small Computer System Interface, SCSI is a high performance specification which lost out (in the consumer market) to the ATA family of specifications due cost-effectiveness (or lack thereof). SCSI provides a host of advantages and features ranging from hot-swapping to native-command queuing as well as the advantage of “not having your entire computer freeze for a moment when one inserts an optical disc into the optical-drive”. SCSI is an extensively parallel interface (hence operations affecting optical drives do not interfere with those affecting hard drives and vice versa). SCSI devices (whether they be hard drives, optical drives, scanners etc) require termination (to maintain signal quality); furthermore there are many “icky” or painfully-annoying configuration operations required to prepare a SCSI system which is another reason it is not common in the consumer market. The SCSI aggregate transfer rates are:

  • SCSI-1 (aka regular SCSI) — 8bit “Narrow” interface providing 5MB/s
  • fast SCSI — 10MB/s on “Narrow”, 20MB/s on “Wide” or 16bit interface
  • fast 20 SCSI (aka ultra SCSI) — 20MB/s on “Narrow”, 40MB/s on “Wide”
  • fast 40 SCSI (aka ultra2 SCSI) — 40MB/s on “Narrow”, 80MB/s on “Wide”
  • fast 80 SCSI (aka ultra160 SCSI) — 160MB/s on “Wide” interface
  • fast 160 SCSI (aka ultra320 SCSI) — 320MB/s on “Wide” interface

SCSI connectors come in 50, 68 and 80 pin configurations; adaptors are available on the market for interfacing between these connectors. It is Important to note that looking at SCSI from the physical-layer, connections need to be done in “straight line”. What this means is that many SCSI cards come with thre connectors (two internal, one external) — you cannot use all three connectors simultaneously (if you did, the physical-layer would look like a “t” and thus parallelism would be seriously messed up). For advanced RAID configurations, SCSI is the only supported interface

Word — A term for two-bytes or 16-bits. In the context of Multi-Word DMA, this refers to the [burst] transfer of multiple words to/from the drive controller without the explicit command for those additional words being sent

Burst — An operation/transaction is said to be “bursted” or “in burst Mode” when the device being read provides more [sequential] data without explicitly being asked to do so. This is based on the principle that “if the controller wants data from location x, it’s highly likely that data from x+1, x+2, x+3 etc will also be desired”

Controller — Generically this refers to some form of chip-logic which allows a computer to interact with a given device. Controllers can be found built-into a motherboard (i.e., IDE/ATA controllers) or via add-in cards (i.e., SCSI controller). Some controllers provide additional features such as RAID.

CRCCyclic Redundancy Checking, this is a basic error checking routine whereby a mathematical calculation (binary polynomial division and remainder is used as the verification unit) to determine if data was corrupted during transmission.

Native Command Queuing (NCQ) — Configurations (both drives and controllers require support) supporting NCQ attempts to queue together a series of instructions and execute them in the most efficient manner possible (efficiency is with respect to the physical layer). As a quick example, suppose data is required from “location” 1000, 55000 and 1005; a non-NCQ drive processes requests literally, 1000->55000->1005 but a NCQ configuration will process it as 1000->1005->55000. The difference is that the time it takes for read-write heads to move from location 1000 to 1005 is miniscule however the transition to/from 5500 is significant. A single queue of operations may not yield impressive performance gains however hard drives are required to execute millions of such transactions and those gains are cumulative

Partitioning and Formatting — Straight out of the box, a hard drive’s file system is “raw” which is unusable. In order to bring the drive to a useable state, it must first be partitioned and then those partitions need to be formatted. Partitioning refers to the process of subdividing the available space on a HDD into logical units (thus making c, d, e etc “drives”). Formatting refers to converting the file system from “raw” to format recognized by the operating system such as FAT, NTFS or EXT2

Cache — Hard drives are mechanical devices: no matter how much you improve the dynamics or increase the spindle speed, a mechanical transfer will always lose out (in terms of performance) to an electrical system. To alleviate/hide the slow nature of hard drives, they [the drives] are often equipped with a small amount of high-speed memory. When a request is received, the drive checks for a match in the cache before “manually” locating the data on the various platters: if there is a cache-hit (i.e., the data required is there) then the data can be immediately transferred thus eliminating seek times. Increasing the amount of cache available on the drive noticeably improves. Hard drives usually come with 2MB, 8MB or 16MB of cache. For some fancy RAID controllers, there is also cache memory present on the controller.

Spindle Speed aka Rotation Speed — Measured in revolutions-per-minute this is literally the mechanical rotation speed of the disk platters. The faster the rotation, the sooner the drive heads can be positions underneath the desired location. Modern drives feature anywhere from 3600rpm to 15,000rpm.

[Average] Access Time — A composite measure of the seek-time and rotational-latency, access time (measured in ms) is the sum total of the time it takes to move the disk head to the appropriate track on the platter (seek time) and the time it takes to move the appropriate sector (of the platter) underneath the drive head (rotational latency). Rotational latency can be reduced by increasing the spindle speed.

Hard Disk Drive Resource Links (Linux System)

January 22nd, 2011 Comments off
This document describes how best to use multiple discs and partitions for a Linux system. Although some of this text is Linux specific, the general approach outlined here can be applied to many other multi tasking operating systems.
This document describes how to copy a Linux system from one hard disc to another.
This document describes how to rescue your Linux partition if MS-DOS deleted it.
This document explains how to plan and layout disc space for a Linux system. It talks about disk hardware, partitions, swap space sizing and positioning considerations, file systems, file system types, and related topics. The intent is to teach some background knowledge, not procedures.
This document covers how to configure disc drives with more than 1024 cylinders for use with Linux.
This document provides a cookbook for creating a root mounted RAID file system and companion fallback rescue system using Linux initrd. There are complete step-by-step instruction for both raid1 and raid5 md0 devices. Each step is accompanied by an explanation of its purpose. Included with this revision is a generic Linux initrd file which may be configured with a single three line /etc/raidboot.conf file for raid1 and raid5 configurations.