n2100 expand raid... HOW?!

[lewinb]

I have an n2100 which until now, has had two 500 GB drives in RAID1. One failed, and since I have to buy a new drive anyway, I would like to expand the raid onto two 1 TB drives. As far as I can tell there is NO upgrade path for installing larger drives. WTF?!

Do I seriously have to buy ANOTHER drive to backup to, (never mind the huge amount of time that it would take to copy 500 GB over the network), then copy all the data back once the new 1 TB RAID1 is built? Ridiculous!!!

Thecus, I know the 5200 has this capability, so what exactly is the upgrade path for the 2100? There should be a module (or better yet, a built-in functionality) for this. If there is, I can't find it. Do you seriously expect that people will never want to swap out their drives for larger ones?

Thecus, please advise what the best process is for this. Thank you.

[lewinb]

Anyone?

It seems like Thecus doesn't always follow these forums very closely.

[lewinb]

OK, so I went ahead and rebuilt the raid using the two disks of different size. Thankfully, the data was mirrored. I made sure that the old drive was listed as Disk one first (NO idea if that makes a bit of difference).

Now, the real problem. I'm going to take out the old drive and keep it as a backup, but HOW to grow the RAID to full capacity on the new, larger drive.

Well, here's what I've found out, without much help from these forums, mind you. (grrrrr).

There's a command-line program specifically for exactly this! I logged in as root via ssh, and found it's already compiled on the n2100. It's mdadm There's no man file for it on the n2100, so see the following:
linuxmanpages.com/man8/mdadm.8.php

Usage for expanding a raid: mdadm --grow device options

mdadm --help for instructions.

So, if anyone happens to have used this before, and could give a little guidance (cough!... Yvon... cough) it would sure save me a lot of time. It would also be EXTREMELY handy if someone at Thecus could build a module that would do this automatically. It CAN'T be that hard, since the program to do it is already there... (can it?)

Thanks!

[worldmaker]

Well if you find the answer I'll be delighted.

I've just decided to upgrade 300 gig to 500 gig drives and found the new array, created by rebuilding twice for each new drive added into the mirror to replace the existing ones, reporting only 300 gig capacity - that's 200 gig missing.

So yes, I'd love to find a way to expand the array on a N2100 without destroying the array or the data and without having to start afresh and copy all the data back and forward from the original drives through my PC onto the new array.

Hmmm, maybe a good challenge for anyone wanting to write a module for it?

[ccomley]

Originally Posted by lewinb

I have an n2100 which until now, has had two 500 GB drives in RAID1. One failed, and since I have to buy a new drive anyway, I would like to expand the raid onto two 1 TB drives. As far as I can tell there is NO upgrade path for installing larger drives. WTF?!

Do I seriously have to buy ANOTHER drive to backup to, (never mind the huge amount of time that it would take to copy 500 GB over the network), then copy all the data back once the new 1 TB RAID1 is built? Ridiculous!!!

Thecus, I know the 5200 has this capability, so what exactly is the upgrade path for the 2100? There should be a module (or better yet, a built-in functionality) for this. If there is, I can't find it. Do you seriously expect that people will never want to swap out their drives for larger ones?

Thecus, please advise what the best process is for this. Thank you.

The 5200 is the only device with Raid-Grow ability. So yes, you will have to re-format to increase your storage capacity. So restore the NAS from your backups. You *do* back up?

[lewinb]

Not True.... Did you read the previous posts?

[lewinb]

Is Yvon alive out there? Isn't this something useful enough that Thecus could kindly weigh in or lend a hand?

For those interested just in the possible answer, look at the last link.


I did some looking, and I found a number of sites that outline procedures using lvm2, which isn't compiled (as yet) for the n2100... In general, they were simply too complicated for me, or assumed a bootable raid or other complications that don't seem relevant.
A few of these are:
http://mkfblog.blogspot.com/2007/11/...partition.html
http://www.debian-administration.org/articles/424

This one seems to imply that mdadm --grow --size=max would actually do it all, but I think I must not be reading it correctly:
http://www.issociate.de/board/goto/1024674/


Finally, I found this site, which uses mdadm and resize2fs.
http://ubuntuforums.org/showthread.php?t=756407

I'm assuming I can ignore everything about creating boot drives and GRUB, and skip straight to the point at which both new drives are installed with healthy RAID1 at the original disk's partition size. Basically, I think I can start at the point "Expand the array to the new size"

It seems fairly straightforward. I'm hoping for some comment on it from people who know better, before I waste a lot of time trying to get it to work. Can it really be that simple?

[Thecus - Yvon]

Dear Sir,

Such operaiton out of N2100 specification already, and it is out N2100 specification already, thus Thecus afraid to any provide suggestion for such operation, also it is out of N2100 warranty and technical support hope for your understanding.

Yvon.

[lewinb]

So, Yvon, Thecus really honestly doesn't forsee that someone running a 320GB RAID1 might want to upgrade to 500 GB????? How can that be out of spec? I can imagine that it would be a very nice selling point, for Thecus to be able to say in advertisements "this device had a built-in module for expanding the RAID without complicated procedures... It's ready to expand when you are!"

[worldmaker]

Thanks for everyone's comments.

I did find one answer on the other Thecus Users Group (it won't let me post the link here but I'm sure you can all find it, ID there is same as here to help in your search).

By then I had to do it the hard way - rebuild the array and use one of the original 320 gig drives on an external housing linked by an SATA connector (far faster than using a USB link!), but still took a couple of days to copy it all over and verify it.

And I WILL keep one of the earlier drives as a long term backup, just in case.

Oh well, back to work.....

[worldmaker]

Originally Posted by Thecus - Yvon

Dear Sir,

Such operaiton out of N2100 specification already, and it is out N2100 specification already, thus Thecus afraid to any provide suggestion for such operation, also it is out of N2100 warranty and technical support hope for your understanding.

Yvon.

Yvon,

Thank you for responding.
Looks like an opportunity for someone somewhere to write an appropriate module to fill the gap. I believe there are discussion on this matter, but don't have the skill to contribute myself.

[lewinb]

While I'm sure it's appreciated, I'd like to save the thanks until this is actually solved... It makes it easier for someone like me, who has to trawl through hundreds of pages of forum posts to find an answer.

Once again, Yvon, it sure would be nice of you to help a little on this current question. Having intimate knowledge of how your machine works, this is a question you should be able to answer rather easily. And it doesn't make any difference to me that it's "out of specification"... I imagine if this can be solved, Thecus will only benefit from having a more robust product. SO you should help!!!

Anyway...

So the question is, WHY can't /raid unmount. The system thinks it's being used for some reason.

Did a little checking... Found a debian forum where it is suggested that perhaps umount is failing due to running processes (daemonized, in their case).

N2100:/app/etc# umount -r /raid
umount: /dev/md0 busy - remounted read-only
N2100:/app/etc#

But as far as I can tell, this is not the case here:

Mem: 180364K used, 336344K free, 0K shrd, 57656K buff, 54448K cached
Load average: 0.01, 0.03, 0.00    (State: S=sleeping R=running, W=waiting)

  PID USER     STATUS   RSS  PPID %CPU %MEM COMMAND
10165 root     R        772 18066  0.7  0.1 top
18029 root     S       1732  2569  0.1  0.3 sshd
 2577 root     S       6656  2162  0.0  1.2 httpd
 2575 root     S       6600  2162  0.0  1.2 httpd
 3620 root     S       6548  2162  0.0  1.2 httpd
 2587 root     S       6508  2162  0.0  1.2 httpd
 2574 root     S       6508  2162  0.0  1.2 httpd
 2576 root     S       6504  2162  0.0  1.2 httpd
 3646 root     S       6472  2162  0.0  1.2 httpd
 2162 root     S       4832     1  0.0  0.9 httpd
 2930 root     S       2352     1  0.0  0.4 smbd
 2942 root     S       2344  2930  0.0  0.4 smbd
 2569 root     S       1488     1  0.0  0.2 sshd
10155 root     S       1444     1  0.0  0.2 nmbd
 3101 root     S       1388     1  0.0  0.2 afpd
 2204 root     S       1096     1  0.0  0.2 cupsd
 3013 root     S       1044  2991  0.0  0.2 upnpd
 3000 root     S       1044  2991  0.0  0.2 upnpd
 2991 root     S       1044  2985  0.0  0.2 upnpd
 3011 root     S       1044  2991  0.0  0.2 upnpd
 9234 root     S       1044  2991  0.0  0.2 upnpd
 2985 root     S       1044     1  0.0  0.2 upnpd
 2211 root     S        836     1  0.0  0.1 udpr

Yes, there are plenty of priocesses running, but none of them should be running from /raid... Yet it is "busy" for some reason.

I also wanted to see what IS mounted as separate filesystems:

N2100:/app/etc# mount
rootfs on / type rootfs (rw)
/dev/root on / type ext2 (rw)
tmpfs on /var type tmpfs (rw)
devpts on /dev/pts type devpts (rw)
proc on /proc type proc (rw,nodiratime)
/dev/cloop0 on /usr/lib type ext2 (ro)
/dev/cloop2 on /opt type ext2 (ro)
/dev/mtdblock3 on /app type jffs2 (rw,noatime)
/dev/md0 on /raid type ext3 (rw,noatime,nodiratime)
N2100:/app/etc#

Finally, I wanted to see exactly what IS SUPPOSED to be mounted:

N2100:/app/etc# vi fstab

tmpfs  /var  tmpfs  defaults  0 0
devpts           /dev/pts         devpts      gid=5,mode=620   0   0
proc             /proc            proc        defaults         0   0
none             /sys             sysfs       defaults         0   0
~
~
~

Unfortunately, I'm not quite sure what to make of it.

There seem to be no processes running that would access /raid, and according to fstab, well I'm not sure... I expected to see a lot more there, based on how many things are mounted. At a loss for the moment. :-/

[lewinb]

Let's look at a different possibility...

The raid will operate in degraded mode with a drive missing. I think I remember reading that the n2100 is a software raid. That being the case, is it possible that the drive could be mounted via a usb enclosure by another OS (Mac/Ubuntu, etc.) which has support for ext2 or ext3?

The Drive Utility with Mac os is capable of creating raids and altering partitions, so could it mount a raid created on another linux box? And then increase the partition?

[lewinb]

Yvon, could you give a little input here? I really think you could be a bit more helpful in finding a *reasonable* solution to this.