Adding one or more drives to an active raid 5 set on N5200B PRO

[Tlaloc]

I'm considering the purchace of a Thecus N5200B PRO, and I'm wondering if it's possible to set it up initially with 3 1TB drives and add the 4th and 5th drive to the raid set as more capacity is needed. Of course in doing so I'd like to see my data preserved between upgrades.

Assuming this works I'd expect an initial capacity of 2TB with 3 drives, growing to 3TB with 4 drives to 4TB with all 5.

I've downloaded the manual but I couldn't find any information on adding more drives to an existing raid set, and whether or not this is supported.

[arthurleung]

In the spec it says "RAID Expansion"
Manual Page 30 should have what you need

[Tlaloc]

I read that page before posting here. Here it is

Expanding a RAID
To expand a RAID 1, 5, 6, or 10 volume, follow the steps below:

1. Replace one of the hard drives in the RAID volume and allow it to
automatically rebuild.

2. Once rebuilt, you can continue to replace any remaining disks in the RAID
array.

3. When you are done replacing hard drives, log on to Web Management.
Navigate to Storage > RAID to open the RAID List screen.

4. On the RAID List screen, select the RAID volume by clicking on its radio
button, and click RAID Config to open the RAID Configuration screen.

5. On the RAID Configuration screen, click Expand.

It seems to only talk about replacing disks in a set, not about adding new ones. I justed wanted to get a confirmation from someone who either knows you can add new disks to an existing raid for a fact or has done this themselves before proceeding with my planned purchase.

[cheburashka]

The Thecus software for expanding raids is just the open source program mdadm. So you can check its man page and work from there... I actually am going to try this in a week or so, because I think its a little ambiguous about the circumstances under which a RAID 5 expansion will work, so if you remind me I'll let you know.

[cheburashka]

I tried it tonight, and you can't expand a three-disc RAID 5 set to four-discs. You can "add as spare" but then the space doesn't increase. If you try "expand" it says "not enough RAID space."

[FTX]

I tried it tonight, and you can't expand a three-disc RAID 5 set to four-discs. You can "add as spare" but then the space doesn't increase. If you try "expand" it says "not enough RAID space."

That's a bummer. Means you need to populate all slots with drives from the start and for upgrade, you need to replace (one by one) the disks with larger disks. Don't like that implementation, especially when you can do such upgrade with the Infrant boxes.

The website mentions: "1 x eSATA connector for capacity expansion". But if you can't go beyond the 5-disk RAID-5, it means you can only use the disks on the eSATA for a separate RAID-group or as separate disks?

gr

Filip

[peterfu]

Interesting - the non Pro version of the N5200 supports raid migration - there it is possible to migrate from a 3 disk RAID5 to i.e. a 4 disk RAID5
br
Peter

[DR]

Yeah you can add the drives... I've just gone from 4 drives to 5 - but I did add the last one as a spare...

[cheburashka]

I'm actually not too disturbed by this. I suspect its really a RAID 5/3-disc issue. I think the issue is that when you set up RAID-5 with 3 discs, the setup is symmetric, and 4-disc isn't, and mdadm can't convert.

That's my suspicion, anyway. I know mdadm can expand RAIDs 0 and 1 when you add discs.

I'm curious if you can go from 4-disc to 5-disc RAID 5 though.

[AndyR_R]

Hi,

I think that's just bug within N5200 pro firmware.
Because this migration is described in N5200 FAQ's.

RAID Migration
Changing the number of disks or RAID level in current RAID configuration. The system will list the possible migration paths, and administrator can choose a possible path. For example, RAID 1 with 2 disks can be migrated to RAID 5 with 5 disks or RAID 5 with 3 disks can be migrated to RAID 5 with 4 disks .
RAID levels currently supported are : RAID 0, 1, 5.

And it is possible to migrate from 3-disk RAID-5 to 4-disk RAID-5 or 4-disk RAID-5 to 5-disk RAID-5
with mdadm (Checked with a software RAID-5 under debian linux:
First add as spare, increase number of disks, then expand)
If N5200 pro has a problem with it (but not N5200 like @peterfu said) this should be a firmware issue.

We are just in process buying a N5200 Pro so I am unable to check this on N5200 Pro

@cheburashka
Im not specialist with RAID-5 but as far as I know information about rebuilding
is spread over all HDD so there is no problem with symmetric or asymmetric organisation

Bye,
Andreas

[cheburashka]

Andreas, you may be right, but when I tried it it didn't give me that option. Also, keep in mind that thecus uses a rather old (1.2) version of mdadm. Also, I was using an n5200 rather than a pro - peterfu's comment was about RAID migration, which is switching from one RAID level to another.

Symmetric/asymmetric was my guess, because they are different algorithms that MDADM can use for allocating blocks a RAID 5 array. (You can cat /proc/mdstat and it will tell you a little.)

I am, of course, open to the idea that I'm wrong.

[peterfu]

peterfu's comment was about RAID migration, which is switching from one RAID level to another.

No, my comment was about RAID5 to RAID5 migration, so adding i.e a 4th disk to an already existing RAID5 with 3 disks.
I go to RAID configuration, then in the advanced section click on Migration - then I have one option RAID5 -> RAID5 to choose. And this is how it should work following the manual - I can't try it, cause I have already a 5 disk RAID5.
But this is described in the non Pro Manual and is not there in the Pro manual.
br
Peter

PS : ah yes, I'm on FW 1.00.10
PPS : added - and the new additional disk should not be added as spare befor migration, so the automatically add as spare should be unchecked

[cheburashka]

Maybe I should have hit the "migrate" button instead of "expand" and "add spare."

[Thecus - Yvon]

Dear Sir,

The RAID Expansion means to enlarge whold RAID disk volume, as like 200GB*5 ->500GB*5, we need insert a new 500GB HDD to replace a 200Gb and rebuild 1 by 1, thus we replace all HDD from 200GB*5 to 500GB*5, we need rebuild the volme 5 times for HDD & 1 times for whole volume, total 6 times.....

The RAID Migrate means if we have 200GB*3 already and went to add a new 200GB HDD using, in this case from WEB confiration page: RAID->Config->Migrate RAID->check RAID5 to RAID5 box-> check 4 HDD (3 old + 1 new ) for migration.

Yvon.

[Thorstense]

@ Thecus - Yvon!

How to add the new HDD for Migrate the Raid5 3HDD to Raid5 4 HDD?

The new HDD can "hotplug" or the Thecus N5200 must be shutdown before insert a new HDD?

Best regards, Thorsten:-)

[Thecus - Yvon]

Dear Sir,

N5200 support HOT swap function, thus we could hot plug the new HDD into N5200 and with following steps.
1. Confirm the new HDD appear from STORAGE->DISKS.
2. STORAGE->RAID->RAID CONFIG->Migrate RAID.
3. Check the RAID LEVEL box RAID5->RAID5.
4. Check the bos of new HDD from AVAILABLE DISK.
5. Click APPLY to start Migration.

Yvon.