When you first build a Raid setup you usually use the latest largest drives you can afford.
At this point can I remind you of the
nomenclature. In computer terminology a "K" is actually
1,024 and therefore one MByte is actually 1,024,000 bytes.
My current system used a pair of 320GByte
hard drives, then when I had a spot of bother with one of them,
I fitted a pair of 500Gbyte versions.
I supplied several Raid 1 setups a few
years ago, using Seagate Barracuda drives which had faulty firmware
that meant all the drives would eventually fail catastrophically.
If this happens a warning message pops up and the faulty drive should be replaced as soon as it's convenient.
Raid 1 which is "mirroring" or a method of having 100% backup which is maintained invisibly to the user, is a really good idea for someone running a business.
In fact it should really be a requirement.
Normally a hard drive will fail in a random fashion when something unexpected goes wrong, like a bearing fails or a chance hardware weakness; perhaps when a badly welded connection within a chip falls off.
Usually hard drive manufacturers will
quote an MTBF or Mean Time Before Failure for their product.
This often represents something like 10 or 20 years or more of
The first problem one has when it comes to fitting a new drive to replace a failed drive is that the new one must have the same, or greater capacity as the existing one. This is not straightforward as the marked capacity, say 500GByte, is too approximate a figure and the manufacturers specifications should be consulted before purchase to ensure the number of available bytes is either precisely the same, or larger.
Now that I understand a little more about the design of Raid systems, I could get round the problem, but it's messy. Read on and you can probably figure out how to do it.
I won't go into the procedure of constructing a Raid 1 setup because this article intends to explain how to change an existing setup.
In the example below I'm fitting a pair of 2TByte SATA drives in place of a pair of 500GByte SATA drives.
The first step is to buy two identical
hard drives. Choose a model with the largest cache as this will
usually be fastest.
Open IMSM and note the details of the old drives and their physical connections. This is important as you must use this information later in the procedure.
Make a note of serial numbers and draw
a sketch of the mechanical position of the drives, just in case
you forget later.
Turn off the computer and remove one
drive, noting which connector it's using.
Turn on the computer.
In fact you'll have difficulty seeing anything other than 500MBytes capacity for the new drive if that was the capacity of the old one. Its other 1.5 TBytes will be hidden from view.
Next, you should switch off and remove the second smaller drive and physically fit the new larger drive, but do not fit its data and power cables at this point.
Booting up the computer will result
in another "degraded" message.
The first step is to remove the large drive from its Raid 1 environment using the "Reset disks to non-Raid" option.
During this process there will be a warning message. It will tell you that all your data will be lost. It's (yet another) product of lazy programmers. The message should include the information that data will not be lost if Raid 1 is your setup.
Go ahead and reset the disks.
Previously I'd used Partition Magic.
This time I used Acronis Disk Director. Everything seemed to
be in place, but the program needed a computer reboot to fix
the new partition and a reboot didn't happen. A forced reboot
didn't have any effect either.
Why neither of these programs worked is a mystery. One suggested turning off the anti-virus, but to no avail. Any ideas anyone?
The program that worked was Norton Partition
Magic. I think that this was the one I'd used a few years back,
but then it hadn't been owned by Symantec.
It worked OK for me however and I was
rewarded with a full 2TByte partition (excluding a little, I
think maybe 8MByte for Windows).
After a reboot open IMSM again, and
carefully identify which of the two hard drives carries your
data. This can only be done by identifying the correct SATA port.
Remember when I said it was important to make notes at the beginning?
Once the migration completion message
has appeared you're done.