Replacing disks and expand raid5 with suspect disks

[DragonWin]

Hi people,

I'm looking for some advice on how to safely replace disks that has been marked as "normal" instead of "Ready" and at the same time (or after) expand the raid5 capacity as the new disks are larger. I have tried to detail the setup / issues below.

Any advice is appriciated

Setup
TS-439 Pro II
Firmware: 3.7.3 Build 20120801
4 x 1 TB disks
Raid5 with all 4 disks
New HDD 4 x 3 TB

Issue
Last week when running the HDD SMART scan (full scan), 2 of my disks were downgraded from ready to normal with the following errors:

Code: Select all

[HDD SMART] HDD 2 Full Test result: Completed: read failure.
[HDD SMART] HDD 4 Full Test result: Completed: read failure.


This has marked the disks as "Normal" instead of "Ready" in the HDD SMART, but the raid is still alive (for now).

I should receive 4 replacement harddisks Monday, but instead of the 1 TB disks that they are replacing these are 3TB disks. According to the built-in help guide, I can not use the expand raid to replace disks and upgrade capacity unless all disk are marked ready. The 2 disks with read failures are marked "Normal" instead of "Ready".

Here is the question
What is the safest procedure to replace all the disk and expand capacity without losing data?

Ps. Yes I have backup of most of it, but it takes a very long time to do a remote restore, and I would lose some data (not to important data but I would like to keep it if possible)

Thanks.

[P3R]

This has marked the disks as "Normal" instead of "Ready" in the HDD SMART, but the raid is still alive (for now).

I think the disks are said to be "Normal" instead of "Good".

According to the built-in help guide, I can not use the expand raid to replace disks and upgrade capacity unless all disk are marked ready.

I can't see anything about the SMART status of individual disks in the online help for the Disk Management, RAID Management page. It says "The drive configuration status must be Ready" which means that your RAID 5 Disk Volume status must be Ready, as opposed to being in a degraded mode.

You should of course begin with replacing the disk that you think is in the worst state (you could use the SMART information to determine which one that may be). There is however a risk with doing the expansion as the remaining disk with reported read failures need to be read during the first disk replacement.

One idea would be to temporarily use one of the 3 TB disks as an external backup in a eSATA/USB external dock/enclosure while the first three disks are being replaced.

[DragonWin]

Hi P3R

Thank you ... that cleared up a lot of my questions / miss conceptions about this.

So the "Ready" state is the Raid5 state and not the disk states, and the Raid5 is currently marked as Ready. You are of cause right in regards to the disk status it's "Normal" and "Good".

I'll use the 4th disk as a backup for the rest of the data while replacing the first 3 disk, good idea there

Thank you for your input, it's appreciated.

[jwalton_mn]

I have the same setup as you with the TS-439 Pro II. I originally had (4) Seagate 1.5TB disks in Raid 5 with bitmap turned ON. When I reached capacity with my volume (after a year of use), I decided to replace the drives with new Seagate 3TB drives (on the approved list). The procedure that I followed was to replace one HDD at a time and wait for the rebuild to complete on each one. It took about 6 hours per HDD to rebuild. When that was completed, I expanded the RAID volume. One quirk that I discovered was that I was not able to start with HDD 1 because it would not join the volume when the rebuild was complete. I tried a couple different drives with the same results. QNAP suggested trying a different slot first and it worked fine starting with HDD4 and working down. Nobody could explain why this worked but since it went smoothly following this order, I'm not complaining.

In your situation with one of your current HDD'd degraded, I would replace that drive first with the 3TB unit and let it rebuild. If it joins the array, you will now have a full raid5 with all good drives. Just replace the rest of the HDD's (one at a time) and rebuild each one until you have a full raid5 using the new 3TB drives. At that point, expand your raid volume. Get rid of the old HDD that was showing normal as it is beginning to fail.

[DragonWin]

Thanks for the reply(s)

I have completed the upgrade of all the disks and expanded the raid size as well.

The procedure above is exactly what I used, and I started with the first suspect disk (disk2), and moved to the 2nd suspect disk (disk4), then replaced the 2 other drives, and expanded the raid volume.