9595A RAID Bay

Available Bays
Installing Drives
   Bottom RAID Bay PCB
Power Microswitch
Remove RAID Bay
Jumpers on Hot Swap Drives
Drive Replacement
Drive Removal
Drive Insertion
RAID without Bays 'n Trays

Available Bays

Installing Drives

1. Find the bay in which you plan to install the drive assembly.
   If a drive assembly is already installed in the bay you plan to use, remove the drive assembly as described in steps 3 and 4 of Removing Internal Drives.
Note: The figures that accompany these steps show the installation occurring in bay 1. These instructions also apply to bays 2 through 7.

2. Prepare the bay for installation of the drive assembly:

a. Insert a small coin into the slot of the small knob located on the left-hand side of the bay. (Do not use more than light pressure to do this! You can snap one "ear" off of the knob. Personal experience)
b. Turn the knob clockwise, one-quarter (1/4) of the way.
c. Slide the knob to the left.
d. Continue with the next step.

3. Install the hard disk drive assembly into the bay:

a. Position drive assembly so the connector is facing rear of server.
b. Align tray with guides, and slide the drive assembly into the bay.
c. Slide the knob to the right until it clicks into place.

Bay parts and their P/Ns

The bay mounting rails are PN 61G3839
The plate that the microswitches are attached to is 60G9814
The blue rod is 42G0033
The bay itself is 42G0026


The PCBs differ in the lack of termpacks and SCSI ID circuitry on the bottom PCB and the SCSI ID jumper on the top PCB. The single drive RAID bay uses the top PCB 61G3843.

RAID Bay PCB 61G3843

Bottom RAID Bay PCB 61G3843

IC1 LTC1155 Dual MOSFET driver
IC2 TL-SCSI285N SCSI termination regulator
P1 Molex power connector
P2 2-pin header to microswitch
P3 3x2-pin SCSI ID jumper header
RP1-4 Resistor Networks

P3 3x2-pin SCSI ID jumper header - the top bay has a jumper on the left pair, the middle has a jumper on the middle pair.

TL-SCSI285 - Regulator for Active SCSI Termination

TL-SCSI285 Fixed-voltage regulator for SCSI active termination

The TL-SCSI285 is a low-dropout (0.7 V) fixed-voltage regulator specifically designed for SCSI alternative 2 active signal termination. The TL-SCSI285 0.7 V maximum dropout ensures compatibility with existing SCSI systems, while providing a wide TERMPWR voltage range. At the same time, the ±1% initial tolerance on its 2.85 V output voltage ensures a tighter line-driver current tolerance, thereby increasing the system noise margin.

The fixed 2.85 V output voltage of the TL-SCSI285 supports the SCSI alternative 2 termination standard, while reducing system power consumption. The 0.7 V maximum dropout voltage brings increased TERMPWR isolation, making the device ideal for battery-powered systems. The TL-SCSI285, with internal current limiting, overvoltage protection, ESD protection, and thermal protection, offers designers enhanced system protection and reliability.

When configured as a SCSI active terminator, the TL-SCSI285 low-dropout regulator eliminates the 220- and the 330- resistors required for each transmission line with a passive termination scheme, reducing significantly the continuous system power drain. When placed in series with 110- resistors, the device matches the impedance level of the transmission cable and eliminates reflections.

Power Microswitch

Removing Microswitch Panel from 3 Bay Cage

First, take off the left rail. Then, unscrew the two screws marked with the red arrows.

Arrow #1 points to the proper assembly of the guide and the switch lever. The curved spring pushes down against the microswitch's lever.
Arrow #2 points to the support that limits the lever's downward travel.

It makes it easier reattaching the switch if you start the screw by the black wire first. That spring steel part that wraps around the switch wants to open up. (the bottom switch is mounted reversed and without a whatever the hell that thing is...

Microswitch Configuration

311SM702-T is an active number right now, but I do not see the travel limit stop or the curled spring.

The switch is marked L119 4A 250VAC, 311SM702-T made by MICRO

Black wire goes to the left terminal "B", yellow wire goes to "Y".

The lever rests on the stop. If you have the lever below it, then your switch will stay "on" regardless of how you turn the blue knob on the Hot Swap (HS) tray. The spring rides on top of the lever, forcing it down.

Remove RAID Bay

Single drive bay shown, three drive bay similar.

Both the three drive and single drive RAID bays have the spring catch on the right side of the bay, facing to the side wall. So to remove a bay, remove the SCSI cable, and unplug the power cable from the PSU. Press in the catch and push the bay out of the DASD structure.

Jumpers on Hot Swap Drives

Some fixed disk options for the 9595 RAID system, were shipped with the SCSI bus termination, address, and auto-start jumpers still installed on the drive. When added to a system, the option should not have these jumpers installed (enabled).
   The excess terminators will cause signal degradation and may result in highly intermittent and difficult to diagnose system configuration errors or operating system failures.
   The 9595A RAID ARRAY system is manufactured with a 3 fixed disk configuration. A total of 4 additional fixed disk options may be installed. No address or termination jumpers should be installed on any of the additional option fixed disks. These options will be automatically addressed and correctly terminated by the "hot plug rack" which is part of the basic 9595A RAID ARRAY system.
   The auto-start jumper should not be installed because it allows the drive motor to spin-up immediately with system power-on. The jumper allows a choice of either the motor starting immediately with system power-on, or to be sequence started one at a time by POST. The total starting surge current of all the fixed disks starting simultaneously may cause the system power supply to "self-protect"* by shutting down.

Note: The 9595A power supply, and other PS/2 system power supplies are designed to "self-protect" if current surges beyond certain limits are exceeded. As options are added, the power supply may be unable to provide sufficient starting surge current for all drives during initial power-on. In this case, the power supply "self-protect" will activate, resulting in the system shut down. This may be corrected by removing the Auto-Start jumper from all the option drives. The "self- protect" action by the power supply will not cause damage.

Drive Replacement

The IBM SCSI and RAID adapters have been designed to allow hard disk drives in hot-swap bays to be removed or installed while the system is running. In some situations, hard disks may be powered down by a RAID Adapter prior to their removal from a hot-swap bay (e.g. failed disk drive); however, this is not a fundamental requirement prior to removing a drive. Only persons trained and knowledgeable in RAID Array service procedures should attempt to service this type system, due to the exposure to possible customer data loss.

When removing drives which are still running, extra care needs to be taken. The following facts should be understood:

  1. The drive needs to be part of a FAULT TOLERANT RAID 5 or RAID 1 Array or the operating system may be unable to access data after the disk drive has been removed.
  2. Only RAID 1 or RAID 5 Arrays allow dynamic rebuilding on a drive that has been replaced.
  3. Only one disk drive can be rebuilt at a time.
  4. The current level of RAID Administration Utility for the specific operating system should be run during disk drive removal. The RAID Adapter marks the drive DDD in this Utility to indicate a command was issued to the drive with no response.
  5. Once a drive's status appears as DDD, a replacement drive can be inserted into the bay. An operator can force a drive which has already been removed from a hot-swap drive bay to be marked DDD by invoking the Drive Information option in the RAID Administration utility. This option is available in all operating systems.
  6. Fixed disk drives are fragile. Care should be taken to avoid rough handling of these devices. Care should also be used when plugging and unplugging hot swap drives to prevent damaging connectors, etc. Use ESD procedures.
    When not installed in a system unit, drives must be protected by being packed in an antistatic bag and option/FRU pack or equivalent. When drives are being handled outside of their packaging the must not be subjected to a shock greater than the equivalent of being dropped 1 inch onto a hard surface. Any shock greater than this level may damage the disks within the fixed disk assembly and could also result in motor bearing damage which may result in noisy operation.
  7. When power is removed from a hot swap drive by the RAID Controller or by user action, the drive will immediately park the heads, lock the actuator in the "landing zone", and begin spinning down. However, the disk spin-down may require up to 20 seconds after power removal. Moving the drive during spin-down should be AVOIDED.

In the event a drive is to be removed from or inserted into a hot-swap bay, the following procedures should be followed.

Drive Removal

If drive is being used in a hotplug application in a 9595A system and is being removed for any reason, it must not be pulled out of the hotplug bay immediately after opening the blue retaining latch. Power will still be applied to the drive and the drive media will still be spinning up until the point when the retaining latch is opened. To avoid possible media damage, allow 10 seconds between opening the retaining latch and removing the drive.

If the drive is being used in an 8641 / Server 500 system, power to the drive motor will be removed automatically in the event of a drive becoming DEFUNCT and the drive may, therefore, be removed immediately. If the drive is being used in an 8641 / Server 500 system and there is a need to remove a drive which is NOT shown as DEFUNCT while the system is operating, the following method should be used:

  1. Unlatch hotplug drive and gently pull drive forwards until it can be felt disconnecting from connector on hotplug backplane (Approx. 10mm, or 1/4 inch, of movement).
  2. Allow 10 secs for motor spindown.
  3. Pull drive completely out of hotplug bay.

Drive Insertion

  1. Ensure the current RAID Administration Utility is running for the specific operating system.
  2. Verify the hot-swap bay where the drive is being inserted appears as DDD in the RAID Administration Utility.
  3. Carefully insert the drive into this hot-swap bay.
  4. Gently seat the drive completely in the backplane connector and latch the drive into the bay.
  5. Follow the directions that came with the system documentation or RAID Adapter to activate the new disk drive and/or begin a data rebuild operation.

On IBM systems, where a Hot-Spare drive is available, the data rebuild operation will begin automatically without the requirement to replace the failed drive. In cases where a Hot-Spare drive is not available, the user or system administrator must use the RAID Administration Utility to initiate the drive rebuild operation.
   As stated earlier, this procedure may differ from implementation by other vendors. Some other vendors' systems may rebuild data automatically when a new drive is inserted. Our procedure requires the user to request the data be rebuilt through the RAID Adapter Utilities in the case where a hot spare drive is not available. This provides the flexibility to reuse the remaining drives as part of another array without performing a rebuild operation, or to start and monitor the rebuild operation when it is convenient for the customer. If automatic unattended rebuild support is desired, then a Hot-Spare drive should be defined.

Note 1: It is recommended that RAID system users periodically perform an "Array Synchronization" (perhaps twice a month) in order to help prevent future rebuild failures. This can be done either via the standalone RAID Adapter Support Diskette in an off-line mode, or while the server is running via the Netfinity RAID services menu.

Note 2: In situations where RAID hot-swap "demonstrations" are being conducted, it is important that Drive Synchronization be done prior to forcing a drive "dead" via a "hot-pull" of a working drive.

The drive that was pulled "hot" must then be either replaced into the array and completely rebuilt, or it must be configured into another array and synchronized prior to being used to store data. This is because the act of "hot-pulling" a disk could result in a partially written sector which would then need to be re-written to correct the ECC bytes or else that partially written sector could cause a rebuild failure later, if used in another array that was not completely synchronized.

RAID without Bays 'n Trays

From Peter:
   I used a 7-drop cable from an 9585 on the first (inner) channel of the Passplay. Installed six HDs and one CD-ROM drive with the IDs running 0 - 6 ... and the Passplay did recognize only the "bays 1 - 4" which correspond with the drive IDs 0 - 3 (0 is the CD-ROM, IDs 1 - 6 are HDs).
   Then I plugged the cable to the second (rear) channel - and it did show only the bays 5 - 7 (lower triple) - but shows the drive infos for the devices installed at IDs 1 - 3 and not ID-0 (the CD-ROM) !!. After that I set the drives to 0-1-2-3 (CD, HD1, HD2, HD3) connected to inner channel and 1-2-3 (HD4, HD5, HD6) connected to the outer channel using a second cable.
   The drive cages from a 9595A "Array" machine are designed to send the IDs 1, 2 and 3 - given that the drives are wired properly with using the thin "drive addressing cable". (Ed. that's part of the drive tray)
   One cage in the top 5.25" bay, one in the lower 5.25" bay and using the proper "server 95 internal cables" result in the IDs 1,2,3 for the top cage, 5,6,7 (!!) for the lower cage (and ID-0 for the CD-ROM in the single Half Height 5.25" bay). See the table below for some "visual aid" on the SCSI-ID confusion.
   So obviously the two "channel" connectors are predefined, the first connector uses the IDs directly with ID2 fixed masked to "0", while the second connector has the ID2 bit fixed set to "1" here.

This leads to the following dependency:

421 = Binary ID-values            | Bay # |
000 = ID-0 = CD-ROM               |   1   |
001 = ID-1 = Top Cage,    drive 1 |   2   |
010 = ID-2 = Top Cage,    drive 2 |   3   |
011 = ID-3 = Top Cage,    drive 3 |   4   |
101 = ID-5 = Bottom Cage, drive 1 |   5   |
110 = ID-6 = Bottom Cage, drive 2 |   6   |
111 = ID-7 = Bottom Cage, drive 3 |   7   |

Attention: These "IDs" in the list above used here are the ones the controller "sees". Not the ones that are really represented through the device SCSI-ID jumpering. ID-7 under normal circumstances is used for the SCSI controller itself - and in fact the "seen" IDs seem to be remapped somehow. See the binary values to explain the dependencies between position and ID sent back to the controller.
   This list proves that the ID4 bit is used to differ between "upper" and "lower" triple pack.

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Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

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