Technical Data of Selected Harddisks

Compiled by Hans-Jürgen Reggel

3.5" SAS/SCSI  ·  2.5" SAS/SCSI  ·  3.5" SATA  ·  3.5" PATA  ·  2.5" SATA  ·  2.5" PATA  ·  1.8"  ·  1"

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Important Notes

About the lists

The lists are intended to give an overview over the available harddisk models with emphasis on sub-2.5" models. However, the fastest and biggest 3.5" and 2.5" models will be listed for reference purposes.

For 3.5" SAS/SCSI, the qualification level for new entries is 15,000 RPM with more than 100GB, or 10,000 RPM with more than 200GB.
For 3.5" PATA/SATA, the qualification level for new entries is 10,000 RPM at any capacity, or 7200 RPM with 400GB or more.
For 2.5" PATA/SATA, the qualification level for new entries is 7200 RPM with at least 80GB, or 100GB or more at any rotational speed.

These lists are based on information available from the respective manufacturers. The lists do not claim to be correct for neither the data source, nor the reproduction process (i.e. reading and typing).

General Harddisk Characteristics

You can always cut down the seek time by creating a partition that is only part of the full capacity. You can never reduce the latency. The latency only depends on the rotational speed of the disk.
A larger harddisk partitioned to the same amount of storage capacity as a smaller harddisk of the same family will have a higher average data rate. The higher capacity model will contain more platters (or use more heads, if appropriate), and using only part of the larger harddisk will result in using only the outer cylinders having a higher transfer rate.
This means that you can only get the best performance by using the largest available 3.5" 15000 RPM SCSI harddisk with the first partition set as small as possible, but as large as necessary.

Portable Storage

If you take a look at the values for vibration and shock, it should be obvious that 3.5" harddisks in general, and 2.5" SCSI harddisks in particular should never be used as portable storage. They can be used as external harddisks, but they should never be exposed to vibration or shock.

3.5" SAS/SCSI Harddisks

It looks like the spell that lasted on SCSI disks for several years is now broken. All remaining manufacturers have 15,000RPM models with up to 147GB, and 10,000RPM models with up to 300GB. The ATA disks were just about to catch up with the sustained data rate of the previous SCSI models, but now it looks like the magic 100MB/s mark will almost be reached. Fujitsu did not state any values, but Seagate and Maxtor state transfer rates of up to 96MB/s and 98MB/s.

One thing you might wonder: Why do the 15,000RPM models only have marginally higher sustained data rates than the 10,000RPM models? Well, the 15,000RPM models only contain 2.5" platters, so the reduced size almost compensates for the increased linear speed. But with the reduced diameter, the seek times are reduced, and due to the higher rotational speed the latency is lower. This results in superior random access performance for the 15,000RPM models. The additional space can take up larger actuators for the head stack, but most of the space will be filled by the solid baseplate serving as heat sink.

Please note that 32bit 33MHz PCI offers a theoretical bandwith of 133MB/s. Two SCSI harddisks operating at the same time can easily take up the whole 32bit 33MHz PCI bandwidth, one single-channel Ultra-160 SCSI controller is enough in this case.
64bit 133MHz PCI-X offers a theoretical bandwidth of 1066MB/s. Think about that before getting a Dual Channel Ultra-320 SCSI controller.

3.5" ATA Harddisks

All 3.5" ATA harddisk manufacturers have now reached the 500GB mark, Seagate already offers a 750GB model, and 1000GB models are announced. Most 3.5" harddisks spin at 7200RPM, the only faster model is the WD Raptor, and the slower 5400RPM models disappear.

2.5" ATA Harddisks

2.5" ATA harddisks are commonly used in Notebooks and therefore are designed to be exposed to operational and non-operational vibration and shock. They are available at rotational speeds of up to 7200RPM and at capacities of up to 160GB for regular 9.5mm models. 200GB 9.5mm and 300GB 12.5mm models are already announced. The fastest 7200RPM models can reach an average sustained data rate of about 53MB/s in the fastest media zone, while older 4200RPM models only deliver up to 19MB/s sustained data rate. If you want to write a DVD at 12× or even 16× speed from a Notebook, you better make sure that your harddisk can provide the data fast enough.

Harddisks of more than 128GB require 48bit LBA support. Some manufacturers seem to avoid any potential problems by offering PATA models of up to 120GB, and only SAT models of more than 120GB.

1.8" Harddisks

During my research, I came across some PC-Card harddisks from Seagate. However, they range from 2.0MB to 43.0MB (it actually took quite a while until I noticed the "MB"), so I should mention that I won't list any 1.8" harddisk below 2GB.

Currently, there are two completely different series of 1.8" harddisks available.

Toshiba builds 1.8" harddiks based on the size of PCMCIA-II and PCMCIA-III cards. The models from the first series are even fully PCMCIA-II compatible, which means that they can be used directly inside the PCMCIA slot of Notebooks. But these models only have 2GB and 5GB storage capacity. The other 1.8" models are available at capacities of up to 80GB (100GB announced) and use either a special PCMCIA-like 50-pin connector, or a new 40-pin ZIF connector.

Hitachi builds 1.8" harddisks based on 2.5" ATA harddisks, but at half length. Hitachi has just introduced a new type of 1.8" harddisk series that basically uses the same form factor as the first series, but with different connectors, and therefore leaving out the pins.
The Travelstar C4K40 and C4K60 AT series have the same 44-pin connectors and interface as 2.5" ATA harddisks and are therfore fully compatible with any devices using 2.5" ATA harddisks and are avaiable at up to 60GB.
The new Travelstar C4K60 CE have a 40-pin ZIF connector and are intended for use in portable devices only, although this might include Subnotebooks. The current models are available up to 60GB, a new series up to 80GB is announced.

1" CF+ Type II Harddisks

The 1" CF+ Type II harddisks, also known as Microdrives, were originally used as storage in digital cameras. These Drives have a much higher current requirement than solid state CF memory cards. The maximum current for 1" Drives is in the range from 250mA to 305mA. The most commonly used Microdrives from the second series by IBM had a maximum current requirement of 250mA. Some devices declared as "Microdrive Compatible" may be designed to provide up to 250mA current and therefore could run into problems when powering Drives with higher current needs. But the Minolta DiMAGE 7 series, for example, can even power the Toshiba 1.8" MK5002MPL PCMCIA harddisk when used with an appropriate passive adapter.

With CF prices dropping to 100 Euro for 8GB, Microdroves become obsolete.

Other 1" Harddisks

One cannot assume that any 1" harddisk will work as storage in a digital camera. Digital cameras usually do not use the ATA interface to access CF cards. Hitachi and Creative already showed that these drives work properly in the original device, but will not work with digital cameras.
Another example are the Cornice Storage Elements which have exactly the same dimensions as a CF Type II card, but use a completely different electrical interface.
The newly announced Hitachi Embedded Microdrive ''Mikey'' is nothing but a design study at this time (January 2005). If the manufacturer cannot give an exact storage capacity (a figure of 8-10GB mentioned), it means that this is just a guess of what could be made at the time of manufacture. If you take a look at the size, you will notice that it is nothing but a Microdrive without the guiding rails and the connectors of a regular CF+ Type II Microdrive. This also means that this drive is not inteded to be used for cameras.

Sub-1" Harddisks

The Toshiba 0.85" harddisks are currently the only known models in this league. The harddisks are mainly intended to be used in small PDAs or cellular phones, but will not play any (or at least no important) role for digital camera users. The width and length would match the SD card format, but these harddisks are way too thick to fit the SD slot (not to speak of the necessary connectors). The only possibe use could be to build CF Type I Drives based on these harddisks.
According to a press release, the 2GB model was supposed to start shipping in January 2005, while the 4GB model is expected to ship mid 2005. The press release also mentions plans for increasing the capacity to 6~8GB in 2006.

Hans-Jürgen Reggel   ·   http://www.hjreggel.net/hdtechdat/   ·   2004-08-19 ~ 2007-01-30