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PC Server 500 - Drive maintenance
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Drive Maintenance
The following section provides information about status indicators for logical and hard disk drives, and the results of a hard disk drive failure. It also contains procedures for replacing defective drives and for redefining the space in an array by replacing logical drives.

Obtaining Drive Status
To see the ID, capacity, and other information about each of the hard disk drives attached to the RAID adapter:
1. Start the RAID configuration program. See 'Starting the RAID Configuration Program´.
2. Select Drive information.
3. Use the Up Arrow (« ) key or the Down Arrow (» ) key to highlight each of the drives shown in the Bay/Array selection list. As a drive is highlighted, the information for that drive is shown at the bottom of the screen.
4. Press Esc to return to the Main Menu.

Note
The status of the hard disk drive determines the status of the logical drives in the array in which the hard disk is grouped.

Bay/Array Selection List: The status of the drives in the Bay/Array selection list is defined as follows:

Status Meaning
CDR CD-ROM drive installed.
DDD Defective. The drive is an online or hot-spare drive that does not respond to commands. (If a RDY drive is defective or powered down, it shows an empty bay (a blank status), not a DDD status).
FMT Format. The drive is being reformatted.
HSP Hot spare. The drive will replace a similar drive that becomes defective in real time. At that time, its status changes to ONL, and its array association is displayed.
OFL Offline. The drive is a good drive that has replaced a defective drive in a RAID level 1 or level 5 array. It is associated with an array, but does not contain any valid data. The drive state remains OFL during the rebuild phase.
ONL Online. The drive is part of an array. If this drive fails, logical drives defined in the array in which this drive is grouped will have a status of offline (if the logical drive is assigned RAID level 0 with a good status) or Critical (if the logical drive is assigned RAID level 1 or level 5 with a good status).
RDY Ready. The drive is recognized by the adapter and is available for definition.
TAP Tape drive installed.
UFM Unformatted. The drive requires a low-level format before it can be used in an array.
Blank Status Any of the following circumstances can cause the status area to be blank:
- No hard disk drive is installed in that bay.
- The bay contains a hard disk drive, but the drive is not inserted correctly.

- An array was deleted and a defective drive is still in the bay.
- A new drive was installed and the configuration program has not been restarted. (The status will change to RDY when the RAID configuration program is restarted.)


Results of a Hard Disk Drive Failure
Depending on the circumstances, there can be several possible results from a drive failure.

Example 1:
- Only one hard disk drive fails.
- A hot-spare drive is defined that is the same or greater size than the failed drive.
- The logical drives in the array are assigned RAID level 1, level 5, or a combination of these two levels.

Then the hot spare will take over immediately.

Note
Data for logical drives assigned RAID levels 1 and 5 is maintained; however, system performance will be reduced. Hot-spare drive capability does not apply to logical drives assigned RAID level 0.

Example 2:
- Only one hard disk drive fails. A hot-spare drive is not defined.
- The logical drives in the array are assigned RAID levels 1, 5, or a combination of these two levels.

Then no data will be lost, but the system will operate at reduced performance until the defective drive is replaced and rebuilt.

Example 3:
If more than one drive fails, all data is lost. Therefore, it is important that you replace and rebuild a defective drive as soon as possible.

Logical and Hard Disk Drive Status Indications
The status of the hard disk drive determines the status of the logical drives in the array in which the hard disk is grouped.
- A single hard disk drive failure (indicated by a DDD status in the Bay/Array selection list) causes logical drives in that array that are assigned levels 1 and 5 to have a Critical status. Data remains in logical drives with a Critical status, but you must replace the one defective hard disk drive promptly, because if two hard disk drives were to fail, all of the data in the array would be lost.

After you install a new hard disk drive, the Replace process changes the drive status from DDD to OFL if there is a Critical logical drive. After the Rebuild process, the hard disk drive status changes from OFL to ONL.

A single or multiple hard disk drive failure causes logical drives in that array that are assigned level 0 to have an offline status. Data in logical drives with an offline status is lost. However, with a multiple disk drive failure, when the defective drives are part of the same array, logical drives in that array will have an offline status. This means that data is lost in all the logical drives in that array, regardless of which RAID level is assigned.

Replacing a Faulty Drive
Note
The hard disk drive indicator light will blink when the drive has failed and needs to be replaced (DDD state only).

To replace a faulty drive:
1. Start the RAID configuration program. See 'Starting the RAID Configuration Program´. If the drive failed while the system was powered down, a screen appears the next time the system is powered on showing you which drive is defective.

2. If the drive is not damaged (for example, it is not inserted correctly):
a. Power-off the system.
b. Correct the problem.
c. Remove the diskette.
d. Restart the system.

3. If the drive is defective:
a. PressY (Yes) to reconfigure the system.
b. Press Ctrl+ Alt+ Del when instructed to restart the system. The Main Menu appears.
c. Select Rebuild device.

At this point, the drive status shows DDD.

Warning
Removing the wrong hard disk drive can cause loss of all data in the array.

d. Replace the defective drive. Refer to 'Removing a Drive from Bank C, D, or E´.
e. After you have replaced the drive, press Enter. The system will reconfigure to include the drive, and the drive's status will change to OFL.
f. Allow the system to complete the configuration (the screen displays a completion message); then select Rebuild drive.
g. Use the Up Arrow (« ) key or the Down Arrow (» ) key to highlight the OFL (offline) drive you want to rebuild; then press Enter.

The progress of the rebuilding process appears on the screen.

h. When the rebuilding process completes, press Esc to return to the Main Menu. The new configuration will be saved automatically.
i. Backup the new configuration (see 'Backing Up Your Disk-Array Configuration´).
j. Select Exit to end the RAID configuration program.
k. Remove the diskette and press Ctrl+ Alt+ Del to restart the system.
Document ID:  DDSE-3UVTUU
Last Modified:  1999-01-22
Copyright 2000 IBM Corporation
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