new flash disk with old configuration of UNRAID....

[nfountou]

hi!

 

Just replaced my damaged flash disk with a new one. Unfortunately I didnt have a recent backup of the flash disk. I used an old one which represented a configuration of 6 disks and not 7 that I have these days.

I started the array with the new flash disk and the old configuration. The array started ok and it only recognized 6 disks. I added the 7th disk in the array, the system erased the disk and add it in the system.(I didnt mind formating it, as the disk was empty anyway). After that I parity checked the system and there were about 7000 parity errors (also there were about the same writes in parity disk). Is this a normal behaviour?I thought that after adding the 7th disk that parity would get synced... Also have in mind that the disks are "clean" as there was no more than a few days that I did a parity check with no errors (before the flash disk failure). Does this mean that if we lose the configuration of the flash disk then we lose the array? is there any other way to bring up an old array from a new flash disk with a fresh UNRAID version?. I ll also parity check the system again and I ll let you know if I still have parity errors ( I believe that they will be 0...)

 

EDIT: I forgot to mention that I have 4.6 version installed...

[Joe L.]

hi!

 

Just replaced my damaged flash disk with a new one. Unfortunately I didnt have a recent backup of the flash disk. I used an old one which represented a configuration of 6 disks and not 7 that I have these days.

I started the array with the new flash disk and the old configuration. The array started ok and it only recognized 6 disks. I added the 7th disk in the array, the system erased the disk and add it in the system.(I didnt mind formating it, as the disk was empty anyway). After that I parity checked the system and there were about 7000 parity errors (also there were about the same writes in parity disk). Is this a normal behaviour?I thought that after adding the 7th disk that parity would get synced... Also have in mind that the disks are "clean" as there was no more than a few days that I did a parity check with no errors (before the flash disk failure). Does this mean that if we lose the configuration of the flash disk then we lose the array? is there any other way to bring up an old array from a new flash disk with a fresh UNRAID version?. I ll also parity check the system again and I ll let you know if I still have parity errors ( I believe that they will be 0...)

 

EDIT: I forgot to mention that I have 4.6 version installed...

It would not matter which version of unRAID you used.

 

The parity disk already had parity based on the 7 disks, when you added it again after starting with the old configuration it added the same parity calcs once more.  (in effect, it corrupted parity)  When you subsequently performed a parity check it fixed the parity.

 

What you should have done is not use the old disk configuration from the restored copy of the flash drive contents.  You should have simply assigned the drives on the devices page and then on the linux command line typed:

initconfig

unRAId would then have used the set of assigned drives for its configuration.  It would have also immediately invalidated the parity drive, and a new parity calc would begin when you start the array, but it would be just re-writing the exact same parity as was already on the disk.

 

Performing those steps in that order would have let the unRAID server use the disk7 as it was and not clear it.

 

It is very easy to recover from a failed flash drive without losing data, just not the way you tried.   If you wanted to skip the entire initial parity calc you could use an additional command line command in between typing "initconfig" and starting the array.  This is only possible if the parity is already correct, as it would have been in your case.

 

That command would be

/root/mdcmd set invalidslot 99

 

It is described in the wiki here: http://lime-technology.com/wiki/index.php?title=Make_unRAID_Trust_the_Parity_Drive,_Avoid_Rebuilding_Parity_Unnecessarily

 

Joe L.

[nfountou]

thats great news...Didnt know that... Thanks! : )

[nfountou]

yeap! everything seems to be ok. 0 errors after parity check (as expected). next time I ll use console as you mention above in order to bring the array back from a dead flash disk issue. thanks and happy new year!