IBM DCS3860, Installation, User'S, And Maintenance Manual

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Replacing multiple DDMs
This section contains guidelines for upgrading DDMs in a storage expansion
enclosure. Read the software documentation and this entire section to determine
whether you should use this procedure, use a modified version of this procedure,
or use a different procedure that is provided by your operating system.
Note: Instructions that are provided with the software should supersede anything
stated in this document.
Before you begin, ensure that you wear an anti-static wrist strap.
Complete one of the following methods to upgrade DDMs:
v
Replacing all the DDMs at the same time
You must back up the data on the affected DDMs and then turn off the DCS3860
storage system.
Attention: Turn off the DCS3860 storage system before you turn off the
EXP3800 expansion enclosure.
After replacing all the DDMs, you must reconfigure the new DDMs and restore
data from backup. See the procedure in “Replacing all DDMs at the same time”
on page 95.
This is the safest way to exchange DDMs without losing data. However, this
method might take a long time to complete because of the backup,
reconfiguration, and restoration processes. In addition, other users are not able
to use the storage system (or any storage expansion enclosures attached to the
storage system) until you finish the procedure. You must use this method on
RAID 0 logical drives.
v
Replacing the DDMs one at a time
In this method, you manually fail each DDM, replace it, and wait for the system
to restore data to the new DDM before installing the next DDM. After you
install the new DDMs, you can configure them to make the additional DDM
space available. See the procedure in “Replacing the drives one at a time” on
page 96.
Using this method, you can replace the DDMs while the DCS3860 storage
system is running, eliminating the downtime that is required if you replace all of
them at once. However, this method is more risky because you can lose data if
the drive restoration or storage system reconfiguration process fails. In addition,
the reconstruction process might take a long time. This method works only on
redundant logical drives (RAID 1, 3, 5, or 6). 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 DDM
malfunctions.
The method you follow 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 storage-management software
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 DDMs.
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IBM System Storage DCS3860 Storage System: Installation, User's, and Maintenance Guide