Chapter 2
Removing and Replacing MEDIArray ZX4 Drives
36
Replacing the Data Drive Set
If you have a spare drive available and a spare drive of the same size
already in any MEDIArray ZX enclosure, you can use the Setup Manager’s
Recover Failed Data Drive operation to recover the data drive set after a
data drive failure or before a failure occurs.
n
Before you begin an online drive recovery operation, you must have a known,
good, same-sized spare drive available to use as the replacement for the bad
drive.
n
An online drive recovery takes longer than an offline (manual) drive repair.
While an online drive recovery is in progress, clients might see degraded
performance.
How Online Drive Recovery Works
The Recover Failed Data Drive operation removes a malfunctioning data
drive from the data drive set, replacing it with a good spare data drive, and
then re-creating (as much as possible) the data that was on the old drive
onto the new drive.
To do this, the Recover Failed Data Drive operation recovers data from:
•
Duplicate file copies on other drives
•
The drive being replaced if the duplicates cannot be read
To do this online, the repair function must remain aware of the fact that the
mirrored copies of the blocks designated for the drive under repair are
changing. It must make several passes to accommodate this, each pass
picking up changes to these blocks that were made since the previous pass.
At some point, the repair function must inhibit I/O for a brief period in
order to make the final pass. Once complete, full bandwidth access is
available to the file system.
