Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-09-05
2003-09-09
Schuberg, Darren (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S801000, C360S097010, C174S050510
Reexamination Certificate
active
06618254
ABSTRACT:
FIELD OF THE INVENTION
The invention claimed and disclosed herein pertains to disk array systems and apparatus for supporting disk drives in a disk array system, and particularly to methods and apparatus to reduce the effects of shock and vibration on disk drives in a disk array system.
BACKGROUND OF THE INVENTION
Disk array systems include several (typically
10
-
30
) disk drives, which are supported in a support apparatus. The support apparatus also supports components, which service the disk arrays. Such support components can include power supplies, cooling fans, and data controllers to control the flow of data to and from the disk drives.
FIG. 1
depicts a front elevation view of typical prior art disk array system
10
. The disk array system includes an outer enclosure
12
, which is supported on a surface “S” (such as a floor or the like). The outer enclosure
12
serves as a general protective enclosure to protect the other components of the disk array, and also acts to seal the disk array system to improve the flow of cooling air circulating within the enclosure
12
. The outer enclosure
12
also includes a front door panel, which is not shown in this view to facilitate the viewing of the other components of the disk array system
10
.
Located within the outer enclosure
12
of the disk array system
10
is a support frame
14
, which is commonly fabricated from metal angle sections and the like. The support frame
14
includes trays
16
. Each tray
16
serves to support a chassis, only one of which is shown as chassis
18
. The chassis
18
defines a plurality of openings
24
A,
24
B,
24
C,
24
D and
24
E. Each opening
24
A-E is configured to receive an operational component of the disk array system
10
. In the example depicted, openings
24
A and
24
B are depicted as receiving respective disk drives
20
A and
20
B. The disk drives can be secured within the chassis openings using latches
22
or the like. Located behind the trays
16
is a back plane
30
which includes electrical connectors
28
and
34
, allowing the functional components to be put into signal and electrical communication with other functional components within the disk array system
10
.
Turning to
FIG. 2
, the prior art disk array system
10
of
FIG. 1
is depicted in a side elevation sectional view. As can be seen, the back plane
30
allows the disk drive
20
A to be connected to the electrical connector
28
. The back plane
30
can further include connectors
28
A and
34
A, allowing flexible cables (not shown) to be used to interconnect the various functional components of the disk array system
10
. As can be seen in this view, the disk drive
20
A includes a data storage disk section
38
which can be accessed by a read-write head (not shown) which is supported on disk arm
36
, allowing data to be transferred to and from the disk section
38
.
A common problem encountered with disk array systems is that of shock and vibration, which can affect the performance of individual disk drives with a disk array system. For example, when a disk drive receives a mechanical force in the way of a shock or vibration, the disk arm
36
and the disk section
38
(
FIG. 2
) can be temporarily misaligned. This can result in a data read/write error, requiring the disk array system to re-read or rewrite the data sector affected by the misalignment. This in turn affects the operational efficiency of the disk array system, resulting in slower data access times. In severe cases mechanical shock and vibration to the disk drive can cause physical damage to the disk drive, requiring that the disk drive be removed for servicing or replacement.
The sources of mechanical shock and vibration which can affect a disk drive originate from three primary sources. The first source is forces external to the disk array system. These can include shock or vibration transmitted through the surface upon which the disk array system is mounted (such as surface “S” in FIG.
1
), and can result from earthquakes and even persons walking on the surface. Another source of external shock is via the external housing (
12
of FIG.
1
), as for example when a person bumps against the housing. The second source of mechanical shock and vibration is from self-excitation. That is, since the disk section (
38
of
FIG. 2
) rotates essentially continuously at a very high speed, a natural frequency inherent to the disk drive itself results. Depending upon the mass of the disk drive and the manner in which the disk drive is supported within the chassis (
18
of FIG.
1
), these self-excitation forces may be resonant, which can cause severe operational problems with the disk drive. The third primary source of mechanical shock and vibration, which can be imparted to a disk drive, is random excitation, which can be transmitted to the disk drive from other functional components within the disk array system, such as other disk drives and cooling fans. The most common source of this excitation is movement of the arms that support the read/write heads inside the hard disk drives.
Turning to
FIGS. 3A and 3B
, schematic diagrams depict how sources of shock and vibration can affect a disk drive in a disk array system.
FIG. 3A
depicts the translational effects that shock and vibration can have on a disk drive
20
mounted within a chassis
18
, which is in turn supported by a frame
14
. Shock and vibration can cause the disk drive to move in directions A
1
and A
2
, which can be in any of the X, Y or Z directions. Self-excitation of the disk drive
20
can be dampened by resistive elements R
1
and R
2
interposed between the disk drive
20
and the chassis
18
, but can be compounded by compliant elements C
1
and C
2
. Likewise, random excitation forces imparted to the chassis
18
can be filtered by resistive elements R
1
and R
2
, but can be amplified by compliant elements C
1
and C
2
. External sources of shock and vibration imparted to the frame
14
can be attenuated by resistive element R
3
interposed between the frame
14
and the chassis
18
, but again can be amplified in a resonant setting by compliant element C
3
.
Turning to
FIG. 3B
, a second effect of shock and vibration on the disk drive
20
is depicted. In this figure the effects are not translational movement, but rotational movement of the disk drive
20
in directions T
1
and T
2
, which can be about any of the three rotational (X, Y or Y) axes. Likewise, the chassis
18
can also experience such rotational movement as the result of the various sources of shock and vibration. As with the translational forces depicted in
FIG. 3A
, the self-excitation forces of the disk drive
20
of
FIG. 3B
which tend to produce rotational movement of the disk drive
20
can be resisted by resistive elements R
4
, but can also be amplified in a resonant setting by compliant elements C
4
. Likewise, random excitation forces, as well as external forces, can cause rotational movement of the chassis
18
, which can be attenuated by resistive elements R
5
, but potentially amplified by compliant elements C
5
. In certain settings, the compliant elements C
4
and C
5
can act together to set up a resonance, resulting in severe translational and rotational movement of the disk drive
20
, as well as the chassis
18
.
The resistive elements R
1
-R
5
of
FIGS. 3A and 3B
can be, for example, a sheet of rubber material placed between the disk drive
20
and the chassis
18
, or between the chassis and the frame
14
. The compliant elements C
1
-C
4
of
FIGS. 3A and 3B
can be, for example, rubberized or otherwise elastically deformable components disposed between the disk drive
20
and the chassis
18
, and between the chassis and the frame
14
. Such elastically deformable components can also include resistive characteristics, and can thus provide both compliant and resistive (i.e., dampening) characteristics. As one example of a compliant element, it is a common practice to dispose a deformable spring steel leaf spring between the chassis
14
and a disk drive
20
to allow the disk
Duong Hung Van
Hewlett--Packard Development Company, L.P.
Schuberg Darren
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