Patent Publication Number: US-2007098281-A1

Title: Damping rotational vibration in a multi-drive tray

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention is related in general to the field of data management systems. In particular, the invention consists of a method for reducing rotational vibration in a multi-drive tray.  
      2. Description of the Prior Art  
      Data storage libraries are used for providing cost effective storage and retrieval of large quantities of data. In a data storage library, data is stored on data storage media that are, in turn, stored on storage shelves or on racks inside the library in a fashion that renders the media, and its resident data, accessible. Data storage media may comprise any type of media on which data may be stored, including but not limited to magnetic media (such as magnetic tape or disks), optical media (such as optical tap or disks), electronic media (such as PROM, EEPROM, flash PROM, Compactflash™, Smartmedia™ Memory Stick™, etc.), or other suitable media.  
      An exemplary data storage library may include a plurality of disparate components such as a power supply, a control module, an interconnect device, one or more communication devices, a blower module for removing heat, and one or more slots for receiving interchangeable components. These interchangeable components may include trays containing data storage devices and control components for managing the data storage devices.  
      Each tray may hold several data storage devices such as hard-disk drives, tape cartridges, optical-disk drives, or the like. These types of data storage devices traditionally operate by spinning a data storage media, such as a platter or disk, over a read/write head. The process of reading from or writing to the media may involve imparting energy to the disk to spin it up from a stopped or low velocity condition to a nominal operating speed. This spin up and subsequent operational rotation may impart significant vibration to the data storage device, its associated tray, and, by extension, the data storage library. Additionally, moving the read/write head radially over the disk may impart additional vibration to the system components. Another source of vibration may be the fan and motor of the blower, which may affect the operation of the data storage drives. These vibrations and associated noise can be bothersome to a system user. Additionally, this vibration may create fatigue on the mechanical structure of the system, may affect the performance of other system components, may result in faulty data being read from or written to the media, or may cause a component failure. Accordingly, it is desirable to have a method for reducing rotational vibration in a data storage system, including one that may have a plurality of data storage devices.  
     SUMMARY OF THE INVENTION  
      The invention disclosed herein employs a damping design to minimize the transfer of vibration from a data storage library, specifically its blower which imparts significant vibrational energy, to its data storage drives. Another aspect of the invention is the reduction of vibration generated by the data storage devices themselves.  
      Constrained layer damping is applied to surfaces which come in contact with the data storage library housing, such as enclosures containing trays of data storage devices. Constrained layer damping may also be applied to the enclosures at the point of contact with the drive trays. Yet additional constrained layer damping is applied to the drive trays. Data storage drives are rigidly mounted on a single plane of each drive tray, providing enhanced rigidity in the critical rotational vibration axis and increasing the effective mass of their associated drive trays.  
      Various other purposes and advantages of the invention will become clear from its description in the specification that follows and from the novel features particularly pointed out in the appended claims. Therefore, to the accomplishment of the objectives described above, this invention comprises the features hereinafter illustrated in the drawings, fully described in the detailed description of the preferred embodiments and particularly pointed out in the claims. However, such drawings and description disclose just a few of the various ways in which the invention may be practiced.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exploded view illustrating a data storage library including a housing, a blower module, and a plurality of data storage device enclosures, according to the invention.  
       FIG. 2  is a rear view of the data storage library of  FIG. 1 , more fully illustrating some of its major components.  
       FIG. 3  is an isometric view of a drive enclosure bay including drive trays containing data storage devices, according to the invention.  
       FIG. 4  is an exploded view of an exemplary constrained layer damping material, according to the invention.  
       FIG. 5  is an isometric view of the chassis of the drive enclosure bay of  FIG. 3 .  
       FIG. 6  is exploded view of the drive enclosure bay of  FIG. 4 , including constrained layer damping, according to the invention.  
       FIG. 7  is an isometric view of the drive tray of  FIG. 3 , including constrained layer damping, according to the invention.  
       FIG. 8  is an exploded view illustrating a data storage library similar to that of  FIG. 1 , including a first set of springs.  
       FIG. 9  is an isometric view of the drive tray of similar to that of  FIG. 7 , including a second set of springs.  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      This invention is based on the idea of using constrained layer damping material applied to surfaces which come in contact with the data storage library housing, such as enclosures containing trays of data storage devices. The constrained layer damping material may also be applied to the enclosures at the point of contact with the drive trays. Yet additional constrained layer damping material is applied to the drive trays. Data storage drives are rigidly mounted on a single plane of each drive tray, providing enhanced rigidity in the critical rotational vibration axis and increasing the effective mass of their associated drive trays.  
      Referring to figures, wherein like parts are designated with the same reference numerals and symbols,  FIG. 1  is an exploded view illustrating a data storage library  10  including a housing  12 , a blower module  14 , a management module  16 , a power module  18 , a switch module  20 , a blade server  22 , a drive enclosure bay  24 , a filler blade  26 , a front bezel  28 , and a media tray  30  containing a CD-ROM drive, a USB port, and a diskette drive.  FIG. 2  is a rear view of the data storage library  10  of  FIG. 1 , more fully illustrating the arrangement of the switch modules  20 , the blower modules  14 , the power modules  18 , and the management module  16 .  
       FIG. 3  is an isometric view of the drive enclosure bay  24  introduced in  FIG. 1 , including drive trays  40  containing data storage devices. A first layer  42  of constrained layer damping material is applied to the vertical surfaces of the drive enclosure bay  24 , according to the invention. This layer  42  of constrained layer damping material reduces the amount of energy transferred to the drive enclosure bay  24  from the rotational vibration generated by the blower module  14 . An exemplary constrained layer damping material  44  is illustrated in  FIG. 4 , wherein a first layer of metal  46  approximately 0.5 mm thick is connected to a second layer of metal  48  approximately 0.5 mm thick by a thin layer of adhesive  50 .  
      The isometric view of  FIG. 5  illustrates the drive enclosure bay  24  of  FIG. 3 .  FIG. 6  is exploded view of the drive enclosure bay  24 , including constrained layer damping, according to the invention. Here, a layer of constrained layer material  52  is applied to the shell  54  of the drive enclosure bay  24 . This layer  52  of constrained layer material reduces the energy transferred to each drive tray (not shown) generated by the blower module  14 . Additionally, this layer  52  of constrained layer material reduces rotational vibration generated by other data storage devices located on other drive trays.  
      Yet another layer of constrained layer damping material  60  is applied to a drive tray  40  as illustrated in the isometric view of  FIG. 7 . Here, this layer  60  of constrained damping material reduces the amount of vibrational energy produced by the blower module  14  that reaches each data storage device  62 . Additionally, this layer  60  reduces the amount of rotational vibration energy transmitted by each data storage device  62  to the drive tray  40  and, subsequently, other data storage devices.  
      The effect of the first, second, and third layers of constrained layer damping material is that the amount of rotational vibration energy reaching each data storage device from the blower module  14  is dramatically reduced. Additionally, the amount of rotational vibration energy reaching each data storage device from other data storage devices is also reduced.  
      Another aspect of the invention involves mounting each data storage device  62  that is associated with a particular drive tray  40  so that they are mounted in a single plane, as illustrated in  FIG. 7 . In so doing, the housing of each data storage device  62  may contribute to the rigidity of the drive tray  40  and increase the mass of the combination of components so as to reduce these components&#39; susceptibility to rotational vibration.  
       FIG. 8  is an exploded view illustrating a data storage library similar to that of  FIG. 1 , including a first set of leaf springs  70 . The springs  70 , in combination with the layer of constrained layer damping material  42  ( FIG. 3 ), reduce the amount of rotational vibration energy transmitted to the drive enclosure bay  24  from the housing  12 . While leaf springs are illustrated for exemplary purposes, other types of springs may also be used.  
      Another set of leaf springs  72  is illustrated in the isometric view of a drive tray  40  in  FIG. 9 . The springs  72 , in combination with the layer of constrained layer damping material  60 , reduce the amount of rotational vibration energy transmitted to the drive tray  40  from the drive enclosure bay  24 .  
      Those skilled in the art of making data storage systems may develop other embodiments of the present invention. However, the terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.