Talk:Hard disk
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IEC Binary Prefixes
My feeling is that all the storage capacity units in this article should be changed to the IEC Binary Prefixes for clarity. The only objection I can see to this is that the traditional usage of the metric prefixes is more widely recognized. However, I feel this is trivial since the binary abbreviations (i.e. KiB, MiB, GiB, as opposed to KB, MB, GB, respectively) are very similar to their metric counterparts, the difference will not be noticed by most readers, but it does a lot in the way of accuracy for this somewhat confusing matter. In any case, the current state of the article is inconstistant in its use of IEC binary and metric prefixes, and something should be done either way. Please post your comments either supporting or objecting to this, I didn't want to make this kind of an edit without first consulting some others. -- uberpenguin 18:10, 2005 Mar 28 (UTC)
Hmm, would anyone be willing to create and/or add a schematic of the interior of a hard drive?
I was wondering what typical random access times might be for various types of drives. I just ran a benchmark program on my HD and I was wondering how it compared to others. KM
Typical current mass-market drives have seek times of around 9ms. Add just over 4ms latency to that (for a 7200 RPM drive) and you have an average access time of about 13.5ms. A seriously high-perforance drive has a seek time of under 4ms and latency of 2ms - i.e., 6ms average access. But these drives sacrifice capacity to achieve their very high performance, require a SCSI interface, and are fairly expensive. Tannin
Tannin, any particular reason for reverting my change to an auto-generated thumbnail? There's really no reason to have separate thumbnail images anymore, and that particular image has already been listed on Votes for Deletion after being replaced at Computer storage. DopefishJustin 03:44, Apr 26, 2004 (UTC)
Yes Justin. It looks terrible, and defaces a perfectly good photograph. If you want to fuzz-up an image, do it to one you took yourself. Tannin
Mr Anon, please note that a hard disk is the internal part of a hard disk drive. The terms are not synonyms.
MFM History
I have no idea why the article claimed that MFM was invented for floppy drives. As far as I've been able to determine, MFM was first used on the IBM 3330 in 1971. The 3330 was most certainly NOT a floppy drive. The first use of MFM for a floppy drive appears to have been the IBM 53FD drive, introduced in 1977. --Brouhaha 08:04, 3 Sep 2004 (UTC)
damage
There's nothing written about the damage to hard disks: we should have at least a cursory explanation of the terms MTBF (mean time before failure), bad sectors/blocks/clusters, BBR (bad block relocation), handling by software and by hardware, hot swapping, something about refurbishing... --Joy [shallot] 14:29, 27 Sep 2004 (UTC)
"Disk Drive Speeds and Performance" http://www.notebookreview.com/forums/topic.asp?TOPIC_ID=112
Decimal vs Binary
It seems like the following claim is incorrect.
“It is important to note that hard drive manufacturers often use the decimal definition of a gigabyte or megabyte. As a result, after the drive is installed it appears that a few gigabytes or megabytes have disappeared. In reality computers operate based upon the binary numeral system. In the decimal number system a gigabyte is 7.5% smaller than in the binary number system. The term "1.44 MB", often used to describe 1440 KB floppies (actually 1.47 MB or 1.4 MiB), introduced an anomalous definition of "megabyte" as 1 × 103 × 210 bytes (1 KKiB).”
The manufacturers actually state a smaller raw capacity of their drives. That is a 30GB harddrive is actually 30GB X 1.024.
The reason that the actual HD is smaller than the advertised number is because some bits are reserved for sector information and thing of the like depending on the OS that’s used.
This is my take on thing. Please let me know what you think, so that we can update this article if required.
- No, the text in the article is correct, if a bit innaccurate on a technicality. The issue here is actually the binary PREFIX versus the metric prefix. This is largely historical; when this first became an issue there were no binary prefixes, so 2^10 bytes was called a kilobyte since 1024 (2^10) is close enough to 1000 (10^3). However, the problem becomes more noticible when you get into the multiple gigabyte range. Most OSes report a GB as what is now called a GiB, or Gibibyte; 2^30 bytes. Hard drive manufacturers continue to use the metric definition of a GB: 10^9, which is obviously less than the binary Gibibyte, because it makes it seem like the drive has a higher capacity than it actually does.
- The blocks used for partition and file system accounting information rarely occupy more than a few KiB, and is utterly insignificant when talking about discrepencies of tens of Gibibytes. I'll edit this section of the article to be a little more clear. -- uberpenguin 15:16, 2005 Apr 4 (UTC)
perpendicular recording
Does anybody have a more detailed description of what perpendicular recording is? I checked over at Valdemar Poulsen page and i couldn't find anything about his discovery as this paragraph from the linked article asserts. "Perpendicular recording was pioneered by the late 19th century work of Danish scientist Valdemar Poulsen, who demonstrated magnetic recording with his telegraphone." [1] (http://news.bbc.co.uk/2/hi/technology/4411649.stm)
Altitude Sensor?
"Some modern drives include flying height sensors to detect if the pressure is too low, and temperature sensors to alert the system to overheating problems."
I do not believe that as of today, April 2005, there are any hard drives that have an altitude sensor as these are still to costly. Every modern drive has a temperature sensor. Channel parameters are typically adapted to the measured temperature. BruceSchardt
Start Stop CSS Testing
I changed the discussion of startstop or CSS testing because the statement that 50% of the drives fail at 50,000 cycles is not correct. Typical specification for a desktop harddrive is 50,000 cycles. However this is not a mean time (cycles) till failure specification. This is a specification that all drives are supposed to achieve without failure. In typical testing a population of several hundred drives are contact-start-stop (CSS) tested for >100,000 cycles. No failures caused by the head-disk interface are allowed at less then 50,000 cycles. Testing for more then 50,000 cycles insures that the HDI design has margin. In proof, the Maxtor Diamondmax 10 hardrive specifies Start-Stop cycles at >50,000 min.[2] (http://www.maxtor.com/_files/maxtor/en_us/documentation/data_sheets/diamondmax_10_data_sheet.pdf) Notebook hard drives are all load-unload designs that never park the heads on the disk, instead the heads are unloaded onto a ramp. This is done to increase the magnitude of non-operational shock that the drive can withstand. BruceSchardt