- IBM switch Users and Maintenance Guide

to use the storage server (or any expansion units attached to the storage server)
until you finish the procedure. You must use this method on RAID 0 logical
drives.
v Replacing the drives one at a time
In this method, you manually fail each drive, replace it, and wait for the system to
restore data to the new drive before installing the next drive. After you install the
new drives, you can configure them to make the additional drive space available.
See the procedure in “Replacing the drives one at a time” on page 86.
Using this method, you can replace the drives while the storage server is
running, eliminating the down time that is required if you replace all the drives at
once. However, this method is more risky because you can lose data if the drive
restoration or storage subsystem reconfiguration process fails. In addition, the
reconstruction process might take a long time. This method works only on
redundant logical drives (RAID 1, 3, or 5). You cannot use this method with any
drives containing RAID 0 logical drives.
Consider backing up your data if you use this method. This safeguards your data
if the restoration and reconfiguration process fails or the new drive malfunctions.
The
method you use depends on the following considerations:
v Which method most closely matches the recommended drive upgrade procedure
that is provided in the operating system or the DS4000 Storage Manager client
documentation
v Which RAID level is used on the affected drives (RAID 0 requires you to replace
all the drives at the same time)
v How much downtime is acceptable as you swap the drives
v How acceptable is the risk of the entire array failing because another drive that is
part of the array has failed during the reconstruction process
v The number of drives in an array. Replacing drives one at a time is better suited
for arrays consisting of 3 to 5 drives. If you have more than 10 drives, consider
replacing all drives at the same time.
Replacing all drives at the same time
Use this procedure to replace all drives at the same time. You must use this method
if you are upgrading drives containing RAID 0 logical drives. All the data currently
on the drives is lost when you replace the drives; therefore, you must back up all
data that is currently on the drives. This procedure also requires you to turn off the
storage server, which makes the storage server (and any attached expansion units)
inaccessible to other users.
To replace all the drives at the same time, perform the following steps:
1. Read the following information:
v The information in “Adding larger-capacity drives” on page 83, particularly
the paragraphs that discuss the differences between the two possible
upgrade procedures
v The information in your software documentation regarding drive upgrades
and installation
v The documentation that comes with the new drives
Read all precautionary notes, kit instructions, and other information. Kit
instructions often contain the most current information regarding the drives
and their installation, plus upgrade or servicing procedures. Compare the kit
instructions with this procedure to determine if you need to modify this
procedure.
84 IBM TotalStorage DS4100 Storage Server: Installation, User’s, and Maintenance Guide