Re: btrfs raid1 and btrfs raid10 arrays NOT REDUNDANT

Goffredo Baroncelli
2014-01-04T15:32:46Z

On 2014-01-04 15:51, Chris Mason wrote:
> I added mount -o degraded just because I wanted the admin to be notified
> of failures. Right now it's still the most reliable way to notify them,
> but I definitely agree we can do better.

I think that we should align us to what the others raid subsystem (md
and dm) do in these cases.
Reading the man page of mdadm, to me it seems that an array is
constructed even without some disks; the only requirement is the disks
have to be valid (i.e. not out of sync)

> Leaving it on all the time? I
> don't think this is a great long term solution, unless you are actively
> monitoring the system to make sure there are no failures.

Anyway mdadm has the "monitor" mode, which reports this kind of error.
>From mdadm man page:
"Follow or Monitor
Monitor one or more md devices and act on any state
changes. This is only meaningful for RAID1,
4, 5, 6, 10 or multipath arrays, as only these have
interesting state. RAID0 or Linear never
have missing, spare, or failed drives, so there is
nothing to monitor.
"

Best regards
GB

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