I have 2TB parity and data disks on a 4.7 server. One has just failed.

 

I will need a new disk - can I recover the data onto a 3TB drive or will I need to purchase a 2TB to be able to recover this data?

 

PS. In case someone asks for a syslog, it's basically a repeat of this error every 10 seconds - and no prior info available due to a syslog-restart (crash)

May 29 04:40:12 FileServer emhttp: mdcmd: write: Input/output error
May 29 04:40:12 FileServer kernel: mdcmd (14432): spindown 3
May 29 04:40:12 FileServer kernel: md: disk3: ATA_OP_STANDBYNOW1 ioctl error: -5

 

And a no smart report is available

root@FileServer:~# smartctl --all /dev/sdi
smartctl 5.39.1 2010-01-28 r3054 [i486-slackware-linux-gnu] (local build)
Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net

Device: /5:0:0:0  Version:
scsiModePageOffset: response length too short, resp_len=47 offset=50 bd_len=46
>> Terminate command early due to bad response to IEC mode page
A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.

You can't have a data drive larger than your parity drive. Your parity drive must be at least as large as your largest data drive.

Which disk failed?

Disk 3 failed (/dev/sdi). It's a WD 2TB EADS drive. Server has not been disassembled for 5 months and this is the first time I have had a drive fail on me.

 

Thank you, I AM aware I cannot have a data drive larget than my parity. I also did figure out I cannot rebuild my parity when a drive has failed, not without loosing the data on that drive. But, I was thinking of something like one of the following options:

 

- Get one 3tb drive, take the array offline and somehow copy the parity drive to the 3TB drive (by preclearing and the dd ??), then rebuild disk3 onto the old 2TB parity drive. Is this possible? Is it necessary to preclear first to ensure 0's on the data area between 2 and 3tb?

 

- Or buy 2 new 3TB drives, mount the first one and copy the data from disk3 to the new unprotected 3TB drive, then replace parity to a 3TB drive and rebuild parity with the first 3tb data drive added to the array as disk3.

 

I'm pretty sure I could do the last option, but how about the first one, is that possible ??

Disk 3 failed (/dev/sdi). It's a WD 2TB EADS drive. Server has not been disassembled for 5 months and this is the first time I have had a drive fail on me.

 

Thank you, I AM aware I cannot have a data drive larget than my parity. I also did figure out I cannot rebuild my parity when a drive has failed, not without loosing the data on that drive. But, I was thinking of something like one of the following options:

 

- Get one 3tb drive, take the array offline and somehow copy the parity drive to the 3TB drive (by preclearing and the dd ??), then rebuild disk3 onto the old 2TB parity drive. Is this possible? Is it necessary to preclear first to ensure 0's on the data area between 2 and 3tb?

 

- Or buy 2 new 3TB drives, mount the first one and copy the data from disk3 to the new unprotected 3TB drive, then replace parity to a 3TB drive and rebuild parity with the first 3tb data drive added to the array as disk3.

 

I'm pretty sure I could do the last option, but how about the first one, is that possible ??

If you introduce unRAID 5, the chance of an error in the upgrade process is very high.  I'd not introduce 5.X at this time until you get the datas drive replaced.   

 

Easiest of course is to purchase a new 2TB drive.  However, that might not be the most cost effective.

 

What I would do is purchase one 3TB drive and use hdparm (or any other MSDOS utility) to set its HPA to effectively make it a 2TB drive.  (exactly the same size as your parity drive)  Than, replace the existing failed drive and get to where you are protected by parity once more.

 

Then... upgrade to 5.0

 

Then... purchase another 3TB drive to replace parity.  Install the new 3TB parity drive, give it some time to be sure it is stable and does not suffer from an early failure.

 

Then,  un-assign the replacement 3TB made to look like a 2TB,  remove the HPA, let unRAID re-construct the data onto it as a 3TB drive.

 

You cannot just use "dd" to replace the existing parity drive with the 3TB drive unless you pay a lot of tricks creating a new super.dat file.  In addition, there is no easy to use way to use the "trust" process in the 5.0 series now.    (any refresh of the unRAID management screen results in the array being set back to the way it was, instead of how you are attempting to force it)

 

Joe L.

You could do a parity-sawp procedure. Then only a single 3TB drive is required.

You could do a parity-sawp procedure. Then only a single 3TB drive is required.

4.7 doesn't support 3TB

You could do a parity-sawp procedure. Then only a single 3TB drive is required.

4.7 doesn't support 3TB

 

The 3TB drive can be formatted with hdparm, as described, to work in 4.7.

You could do a parity-sawp procedure. Then only a single 3TB drive is required.

4.7 doesn't support 3TB

 

The 3TB drive can be formatted with hdparm, as described, to work in 4.7.

It is not really formatted, but you'll need to add a HOST-PROTECTED-AREA (HPA) to occupy the top third of the disk, artificially making it look to the disk controller as a 2TB drive.    You might be able to perform that step with the

hdparm -N p3907029168 /dev/sdX

command.

You'll need to set the size appropriately.  (and know the correct disk too)

 

When done, the hdparm command should report it as having a different physical vs. logical size.

hdparm -N /dev/sdX

 

Typically you can only change the size once per power cycle of a disk.  (it is a safety feature built into disks)

 

Once the 3TB drive looks like a 2TB drive, you can proceed as normal.    Later, you can use the same tool to make the size bigger as part of the process to use the full capacity of the drive... after you upgrade to 5.0 and after you replace the parity drive with a 3TB drive.

 

On some hardware the hdparm -N command will not work.  You'll heed to use one of the MSDOS tools as mentioned in the wiki under HPA.

 

Joe L.

 

 

I'd put the shrunken 3TB drive in parity now. Then, after the upgrade to 5.0, remove the HPA and rebuild parity.

I'd put the shrunken 3TB drive in parity now. Then, after the upgrade to 5.0, remove the HPA and rebuild parity.

I disagree.  I've performed a parity swap of a disabled disk in my old server.  It takes far longer.

 

My approach is to do as little as possible since he has a disk that has failed.  (my preference actually would be for him to just purchase a 2TB drive and replace the failed drive, but that might not make economic sense)