Difference between revisions of "Non-removable-media disk"

From Computer History Wiki
Jump to: navigation, search
(Interesting to read the patents as to why HDAs were the Right Thing)
 
(helium reduces turbulence)
 
Line 1: Line 1:
−
'''Non-removable-media disk'''s were the generation of [[magnetic storage|magnetic]] [[disk]] [[mass storage]] [[peripheral]]s after the previously ubiquitous [[removable-pack disk‎]]s. They used 'head/disk assemblies' (HDAs), which packaged the [[platter]]s and the [[head]]s in a pre-assembled, sealed (in 'clean-room' conditions), unit. The sealed HDA was, and remains, a key step in improving the storage density (and thus capacity) of disk drives.
+
'''Non-removable-media disk'''s were the generation of [[magnetic storage|magnetic]] [[disk]] [[mass storage]] [[peripheral]]s after the previously ubiquitous [[removable-pack disk‎]]s. They used 'head/disk assemblies' ('''HDA'''s), which packaged the [[platter]]s and the [[head]]s in a pre-assembled, sealed (in 'clean-room' conditions), unit. The sealed HDA was, and remains, a key step in improving the storage density (and thus capacity) of disk drives.
  
 
The technical rationale for using sealed HDAs has several parts, but an important one is as follows. To maximize storage density, the head must be 'flown' as close to the surface of the platter as possible; at such heights, even tiny dust particles can cause a [[head crash]]. If outside air is being introduced, it is difficult to filter out the smallest particles; and in any event, the filters must be replaced regularly, a maintenance headache. Sealing the HDA in a 'clean room' environment avoids these problems.
 
The technical rationale for using sealed HDAs has several parts, but an important one is as follows. To maximize storage density, the head must be 'flown' as close to the surface of the platter as possible; at such heights, even tiny dust particles can cause a [[head crash]]. If outside air is being introduced, it is difficult to filter out the smallest particles; and in any event, the filters must be replaced regularly, a maintenance headache. Sealing the HDA in a 'clean room' environment avoids these problems.
  
−
It was later discovered that filling the HDA with helium was advantageous, due to its lower density.
+
It was later discovered that filling the HDA with helium was advantageous, due to its lower density; that reduces turbulence around the head.
  
 
{{semi-stub}}
 
{{semi-stub}}

Latest revision as of 12:27, 19 August 2023

Non-removable-media disks were the generation of magnetic disk mass storage peripherals after the previously ubiquitous removable-pack disk‎s. They used 'head/disk assemblies' (HDAs), which packaged the platters and the heads in a pre-assembled, sealed (in 'clean-room' conditions), unit. The sealed HDA was, and remains, a key step in improving the storage density (and thus capacity) of disk drives.

The technical rationale for using sealed HDAs has several parts, but an important one is as follows. To maximize storage density, the head must be 'flown' as close to the surface of the platter as possible; at such heights, even tiny dust particles can cause a head crash. If outside air is being introduced, it is difficult to filter out the smallest particles; and in any event, the filters must be replaced regularly, a maintenance headache. Sealing the HDA in a 'clean room' environment avoids these problems.

It was later discovered that filling the HDA with helium was advantageous, due to its lower density; that reduces turbulence around the head.

External links

Retrieved from "https://gunkies.org/w/index.php?title=Non-removable-media_disk&oldid=31236"