SOLVED Can degraded HDD help resilvering?

[tij]

I am new to FreeNas ... just set up my first one a week ago ... everything running smoothly so far

Tried searching this forum and google ... but could not find anything to my question, which is:

When one of the disk is flagged degraded ... and new disk is put for resilvering ... can FreeNas use degraded disk to help rebuild it? (ie straight copy from degraded disk to new disk ... and rebuild whatever cannot be recovered from degraded disk?)

 

[Chris Moore]

can FreeNas use degraded disk to help rebuild it? (ie straight copy from degraded disk to new disk ...

It doesn't work that way, 'straight copy', but the disk can be used by the system during the rebuild process.
Rebuilds are always done by looking at all the data, so all the disks in a vdev will be used extensively and even disks in other vdevs of the same pool will be used some, to collect the data that ZFS needs to rebuild the array.

 

[Ericloewe]

In a nutshell: If the disk is not completely dead or completely slowing your system to a crawl and you have enough ports, keep it in while the new one resilvers.

 

[tij]

So resilvering can be done with damaged disk ONLINE (doc.freenas.org says i need to take damaged disk OFLINE and then replaced it)?

So back to my original question ... assuming i can keep damaged disk ONLINE while resilvering ... does freenas use it to help rebuild its replacement?

The reason i ask ... if its true, the survivability of array will improve ... some data can be partially recovered from damaged disk, hence reducing amount of data need to be rebuild (in case of raidz) or read (in case of mirror) from remaining disk(s) ... hence reducing stress on remaining disk in array

Apologies if this is too trivial ... i am truly new to this (whole life been on Windows)

 

[Ericloewe]

does freenas use it to help rebuild its replacement?

Yeah.

 

[tij]

thx for your help