7,200+ RPM Drives in a Model 90 / 95?

Drives are devices that your server uses to read and store data.  Several types of drives are available, such as: 
 o CD-ROM 
 o Diskette
 o Hard disk (RAID Bays with Hot Swap)
 o Optical disc 
 o Tape 

 Adding different types of drives enables you to read other types of media, and provides more storage for your server. 

 Some drives have a special design called small computer system interface, or "SCSI."  This design allows you to attach multiple drives to a single adapter or controller. 
 Note:  Any information about SCSI drives also applies to other SCSI devices, such as scanners and printers. 

 Inside your server there is a SCSI-2 adapter, which manages the SCSI drives. This adapter has both an internal and external connector. By chaining drives (connecting them together with cables), you can attach additional external SCSI drives.  Your server supports a total of seven SCSI drives (internal and external). 


 Each SCSI device connected to the adapter needs a unique identification (ID) so the adapter can identify the devices. The adapter then can ensure that different devices do not attempt to transfer data at the same time. (Refer to the instructions that came with your SCSI device for information about setting a SCSI ID.) 

 When SCSI devices are chained, both ends of the chain require a terminator. The purpose of these terminators is to ensure that the quality of the signal is maintained throughout the SCSI chain. The internal SCSI drive in bay C has a terminator activated, so any additional SCSI internal devices do not need a terminator. 

 The external SCSI connector has a built-in terminator, which is automatically enabled when nothing is attached to it. The external SCSI connector is on the back of the server in slot 1. (Refer to the instructions that came with the device for more information about terminators.) 


 Internal drives are installed in bays.  The bays are referred to as A, B, C, D, and E.  Your server comes with a diskette drive in bay A and a SCSI hard disk drive in bay C. 

 Drives come in a variety of heights. You can install half-high drives that are less than 41.3 mm (1.6 in.) high in any of the bays.  Drives that are greater than 41.3 mm (1.6 in.) high (full-high) can be installed in bay C or bay D. Bays C and D can each hold two half-high drives or one full-high drive. 

 Different types of hardware (slides, rails, and trays) are used to install a drive in a bay.  The type and size of the drive, as well as where it is to be installed, determine what hardware you will need when installing it. 

 Cover plates (sometimes called bezels) cover the front of each installed drive. If you install a drive that uses removable media (diskette, tape, optical disc, or CD), you will need to change the cover plate. 

 Both internal and external drives connect to your server with cables. Your server has three types of internal drive cables: 
 o A flat-ribbon cable connects internal diskette drives and certain tape drives.  The cable has three connectors, one of which is attached to the diskette drive in bay A. 
 o Another cable connects internal SCSI drives. This cable has five connectors, one of which is attached to the hard disk drive in bay C. 
   Note:  The 8-bit SCSI-2 cable that comes with your server has five connectors. You can purchase a 16-bit SCSI-2 cable for use with 16-bit devices.  The 16-bit SCSI-2 cable has seven available connectors plus one connector that has a terminator attached. 
  o Each drive that has a power-cable connector, is attached to the power supply with a 4-wire power cable.  All of the connectors on the power supply are interchangeable. One of these cables is attached to the hard disk drive in bay C. 

 If you attach external SCSI devices to your server, you should purchase the cables when you buy the devices. Your IBM Authorized Dealer or Marketing Representative can help you select the correct cables. 

 If you select Enable Fast External SCSI from the Change Configuration menu, be aware of the following: 
 o When chaining external devices, the maximum external cable length you can use is 3 meters (10 feet). 
 o When chaining external Model 3510 SCSI Storage Enclosures, you cannot attach more than three enclosures. 
 o Only one Model 3511 External Storage Enclosure for SCSI Devices can be attached. 
 Refer to the following table for cable lengths. 

SCSI Cable Lengths 
SCSI Card-to-Option Cable (original 8-bit cable) 1.5m (58")
SCSI Option-to-Option Cable (original 8-bit cable) 0.7m (27")
SCSI Controller Cable (for 3532) dual-connector external SCSI cable 1.5m (58")
SCSI Device-to-Device Cable(for 3532) 50/50-pin dual-connector external SCSI cable 0.7m (27")
SCSI Storage Enclosure Model 3510 (internal cable) 0.3m (12")
External Storage Enclosure for SCSI Devices Model 3511 (internal cable) 1.3m (51")
SCSI-2 8-Bit Internal Cable 95 1.2m (47")
SCSI-2 8-Bit Card to Option Cable 1.5m (58")
SCSI-2 Option to Option Cable (Short) 0.27m (10")
SCSI-2 16-Bit Internal Cable 95 1.39m (55")
SCSI-2 16-Bit Card to Option Cable 1.5m (58")
SCSI-2 16-bit Option to Option Cable 0.27m (10")
  1. The Model 3510 SCSI Storage Enclosure holds one SCSI device. 
  2. The Model 3511 External Storage Enclosure for SCSI Devices can hold up to seven SCSI devices. 
  3. The Model 3532 is a 2.3GB external SCSI tape drive. 

 If you have installed the maximum number of SCSI devices your SCSI adapter supports, and you plan to install more SCSI drives, you can install another SCSI adapter. Then, you can connect the additional devices to the new adapter. 

7,200+ RPM Drives
>Why not a True-Blue IBM Ultrastar XP-S4x @ 7200?  They'r available. 
   I would be extremely careful with these 7.200 rpm server drives in Mod. 90 or 95. Especially the 90-case is rather tight and all 7.200 rpm drive (any manufacturer) emit a lot heat and *require* constant airflow over the drive(s).
   This is definitely not given in the 90 and 95 case. Therefore IBM designed the 500 case - which has a "fan rear wall" behind the harddisk bays to maintain the airflow for cooling the 7.200 rpm drives.
   None of the IBM 7.200 rpm drives has been announced for the use in Mod. 90, 85 or 95 ... the best recommendation for these machines is the IBM DCAS series with 5.400 rpm, which are fast enough for the IBM SCSI controllers coming with these machines and are (were ?) avaiable in 2.16GB as well, which is the size required for the boot drive, which cannot be over 3.94GB due to the structure of the IML partition.
   A second drive could be 4.5GB or even larger (though: haven't tried to go to 9.1GB).

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