On 2011-02-08 21:39, Brandon High wrote:
On Tue, Feb 8, 2011 at 12:53 PM, David Dyer-Bennet<d...@dd-b.net> wrote:
Wait, are you saying that the handling of errors in RAIDZ and mirrors is
completely different? That it dumps the mirror disk immediately, but
keeps trying to get what it can from the RAIDZ disk? Because otherwise,
you assertion doesn't seem to hold up.
I think he meant that if one drive in a mirror dies completely, then
any single read error on the remaining drive is not recoverable.
With raidz2 (or a 3-way mirror for that matter), if one drive dies
completely, you still have redundancy.
Sure, a 2-way mirror has only 100% redundancy; if one dies, no more
redundancy. Same for a RAIDZ -- if one dies, no more redundancy. But a
4-drive RAIDZ has roughly twice the odds of a 2-drive mirror of having a
drive die. And sure, a RAIDZ two has more redundancy -- as does a 3-way
mirror.
Or a 48-way mirror (I read a report from somebody who mirrored all the
drives in a Thumper box, just to see if he could).
--
David Dyer-Bennet, d...@dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info
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