Re: SMART statistics for 40, 000 disk drives, from Backblaze

Hi John,

<SNIP>

> I think it'd be useful to automate the recovery of initial drive
> failures in a replicated environment.  For example, if you have RAID,
> online backups, or dual copies of items, then when a sector or group
> of sectors fails, they can be overwritten with the correct data, and
> thus remapped by the drive.  This *should* be an automatic process,
> particularly at scale when you have many thousands of drives, but at
> the moment it isn't.

<SNIP>

> Does Linux software RAID, or ZFS, already do this "write over a bad
> sector" recovery?

I have had correspondence with Neil Brown over the years concerning this feature of the mds (software raid) driver.  Nine years ago, this was near the top of Neil's "to-do list":

http://neil.brown.name/blog/20050727141521

(see item "Don't kick drives on read errors"). My understanding is that was in fact implemented and is now part of the standard mds driver.  But I'm not sure, perhaps someone else here can confirm or deny that.

Cheers,
	Bruce



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