On Jul 12, 2014, at 7:30 AM, Vlad Dobrotescu [off-list ref] wrote:

Since it seems you have a very healthy view of real-world RAID,
could you point out any significant issues when using a disk as
a degraded md RAID1 (not accidental, but on purpose)?

Intentionally degraded raid1 seems oxymoronic to me. Like fat free ice cream. Uptime/data availability is the purpose of RAID, not backup. It sounds like a member drive is being used as a shelf or offsite backup, with periodic catch-up resyncing. If it's an n way mirror with 3 drives, two left connected, one off-site, then while technically degraded you could still lose one drive and have uptime and a backup. But I still think that's the wrong way to do it — this is probably more of a philosophical argument than a technical one.

Chris Murphy

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