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 Post subject: NSA2401 Raid5 Down
PostPosted: Sat May 03, 2014 4:15 pm 
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Joined: Sat May 03, 2014 3:46 pm
Posts: 5
Greeting to all NAS experts here, it seem I have got myself into a messy situation which I would like to seek your suggestions. I have a NSA2401 running 24/7 for 3 years now, replaced a few HDD along the way until yesterday its just died on me.

config: RAID5 no spare


I will try to keep the story short; yesterday the 2401 buzzer rang and then I expect it has to be another faulty drives but that wasn't the case. It was disks 1,4 gone faulty by the red LED indicator. I checked the admin UI but there was no logs or warning message displayed, the log just showed a I/O error from disk4 from a few days ago. So I shut down the 240, re-seated the drives and then power on again, but this time only disk1 shows a fault. So I powered the 2401 down again, replaced a brand new disk1 and I left it rebuild the RAID5 (10hrs)

So next morning I check the NSA again but it turns out the RAID is offline, all folders are inaccessible. It turns out the new disk1 has been assigned as a spare disk which isn't supposed to. (and disk4 still flashing RED led.) Without touching anything else, I rebooted the unit again and the folders are accessible again in the degraded RAID mode.

I was curious why the disk1 is considered as spare disk, so I reseated all 4 disks one by one while the NSA is powered on ........ and this is when I think I have killed the RAID....... now the web UI says there is a raid5 but no volumes are displayed...... so I am just wondering is there anyway that I can manually bring the volume back or at least let me backup the data out of it?


I replaced disk4 just under 6months ago, and the log and the UI didn't any S.M.A.R.T. Error at all...... just one entry of I/O error from a few days ago.....any ideas? Thanks!


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 Post subject: Re: NSA2401 Raid5 Down
PostPosted: Sun May 04, 2014 2:42 pm 
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Joined: Mon Jun 16, 2008 10:45 am
Posts: 5974
When a disk shows I/O errors it should be exchanged immediately. And unfortunately SMART doesn't always warn before a disk dies.

I *think* your disk 1 was assigned as spare, because the array had dropped 2 disks, making it impossible to add disk 1 to the array. Not enough data left to rebuild it.

It might still be possible to rescue your data, depending on the shape of the disks. To do so the 3 original disks should be connected simultaneously to a Linux system. That can be your NAS, if you have (root) shell access.
Oh, and don't trash your replaced disk yet, it can be needed.

Further you should think about where to copy the data to, if the array can be fixed.


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 Post subject: Re: NSA2401 Raid5 Down
PostPosted: Mon May 05, 2014 8:15 am 
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Joined: Sat May 03, 2014 3:46 pm
Posts: 5
thanks Mijzelf, I guess I will try to mount the disks 2,3,4 then (I am not even sure does disk one have anything in it...)

All i know is this NAS 2041 uses RAID 5 but what other info do I need inorder to mount it? Ext3/4??? Parity rotation? or simply just don't care and plug them in anyways?

I have been trying to salvage the data using ReclaimXX (win32 app) , unfortunately the data are just rubbish with no value to me.

PS> when I load up the ReclaimXX software , its was able to detect the Linix MDs but there is an odd thing such as there are 3 volumes displayed:

1.) Zyxel (1024GB ) <-- this has nothing
2.) *some wierd numbers (512mb) <-- this has nothing as well
3.) *same numbers as #2 with more characters goes after it. (2.7TB) <- this has rubbish data......

so would this be any significance?


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 Post subject: Re: NSA2401 Raid5 Down
PostPosted: Mon May 05, 2014 11:13 am 
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Joined: Mon Jun 16, 2008 10:45 am
Posts: 5974
Quote:
All i know is this NAS 2041 uses RAID 5 but what other info do I need inorder to mount it? Ext3/4??? Parity rotation? or simply just don't care and plug them in anyways?
Well, to start with, you should plug them in anyway. Then you can search the data partitions using
Code:
cat /proc/partitions
This shows all (recognized) block devices, disks, partitions, raid arrays, ...

Search for 3 equal sized (size is given in kB) devices sdxn, where x is three different characters, and n is the same number. When you have located them, execute
Code:
mdadm --examine /dev/sda3
mdadm --examine /dev/sdb3
mdadm --examine /dev/sdc3
where you exchange the [abc] by your found characters, and 3 by your found number. Post the output. It will tell how the raid array is organized, and which role each disk has.
Quote:
3.) *same numbers as #2 with more characters goes after it. (2.7TB) <- this has rubbish data......
2.7TB is the total size of the array, I guess? 4 *1TB minus parity?


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 Post subject: Re: NSA2401 Raid5 Down
PostPosted: Mon May 05, 2014 4:05 pm 
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Joined: Sat May 03, 2014 3:46 pm
Posts: 5
Quote:
3.) *same numbers as #2 with more characters goes after it. (2.7TB) <- this has rubbish data......
2.7TB is the total size of the array, I guess? 4 *1TB minus parity?[/quote]

no idea about the 2.7T..... these are WD RE4 2TB disks .... 2.7T perhaps it is showing as degraded capacity?

I will be out of town for a week, I will update with you after my return then.


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 Post subject: Re: NSA2401 Raid5 Down
PostPosted: Mon May 05, 2014 4:53 pm 
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Joined: Mon Jun 16, 2008 10:45 am
Posts: 5974
A degraded array has no different size than a healthy array.

You are using 2TB disks, but I guess originally the disks were smaller? A raid array doesn't automagically grow when you exchange all disks one by one by bigger disks.


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 Post subject: Re: NSA2401 Raid5 Down
PostPosted: Tue May 06, 2014 4:58 am 
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Joined: Sat May 03, 2014 3:46 pm
Posts: 5
I think they are all 2TB disks to begin with, and yes the capacity does change in my case, I recalled that the Raid was ~3.8TB at the beginning but as soon as one disk is down, the raid capacity drops to a lower level. In the past I have received complaints from my co workers about the insufficient capacity of the raid, then I realize that was the first time that the RAID disks started to break. (or could it be the 2401 itself created a 1TB recycle bin capacity at the back ground? )

I want my data back :( :( :(


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 Post subject: Re: NSA2401 Raid5 Down
PostPosted: Mon May 12, 2014 4:42 pm 
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Joined: Sat May 03, 2014 3:46 pm
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yup looks like 2 out of 4 drives are in bad shape, that's why the disk 1 was left as spare even after rebuild...... oh well time to send these drives off to data recovery center (if that is even an option...) Now this puts me into thinking to change all of my servers from RAID5 to RAID6...... :|


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 Post subject: Re: NSA2401 Raid5 Down
PostPosted: Mon May 12, 2014 5:54 pm 
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Joined: Mon Jun 16, 2008 10:45 am
Posts: 5974
WSAF wrote:
(if that is even an option...)
That is certainly an option, unless the dropped disks are dead. It is relatively easy to re-insert a dropped disk in a degraded array. A disk is dropped when it gives a single unrecoverable read error. That means that 512 bytes are lost, while the disk can still contain 2TB healthy bytes.

Quote:
Now this puts me into thinking to change all of my servers from RAID5 to RAID6...... :|
You should just have a backup. A raid6 arrray can also fail. And because all disks are in the same box, you also have the risk of lightning, theft, a failing powersupply killing all disks, as it's last action, filesystem corruption, ...


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