Responses inline... On Tue, Mar 16, 2010 at 07:35, Robin Axelsson <gu99r...@student.chalmers.se>wrote:
> I've been informed that newer versions of ZFS supports the usage of hot > spares which is denoted for drives that are not in use but available for > resynchronization/resilvering should one of the original drives fail in the > assigned storage pool. > That is the definition of a hot spare, at least informally. ZFS has supported this for some time (if not from the beginning; I'm not in a position to answer that). It is *not* new. > > I'm a little sceptical about this because even the hot spare will be > running for the same duration as the other disks in the pool and therefore > will be exposed to the same levels of hardware degradation and failures > unless it is put to sleep during the time it is not being used for storage. > So, is there a sleep/hibernation/standby mode that the hot spares operate in > or are they on all the time regardless of whether they are in use or not? > Not that I am aware of or have heard others report. No such "sleep mode" exists. Sounds like you want a Copan storage system. AFAIK, hot spares are always spinning, that's why they are hot. > > Usually the hot spare is on a not so well-performing SAS/SATA controller, > so given the scenario of a hard drive failure upon which a hot spare has > been used for resilvering of say a raidz2 cluster, can I move the resilvered > hot spare to the faster controller by letting it take the faulty hard > drive's space using the "zpool offline", "zpool online" commands? > Usually? That's not my experience, from multiple vendors hardware RAID arrays. Usually it's on a channel used by storage disks. Maybe someone else has seen otherwise. I'd be personally curious to know what system puts a spare on a lower performance channel. That risks slowing the entire device (RAID set/group) when the hot spare kicks in. As for your questions, that doesn't make a lot of sense to me. I don't even get how that would work, but I'm not "Wile E. Coyote, Super Genius" either. > > To be more general; are the hard drives in the pool "hard coded" to their > SAS/SATA channels or can I swap their connections arbitrarily if I would > want to do that? Will zfs automatically identify the association of each > drive of a given pool or tank and automatically reallocate them to put the > pool/tank/filesystem back in place? > No. Each disk in the pool has a unique ID, as I understand. Thus, you should be able to move a disk to another location (channel, slot) and it would still be a part of the same pool and VDEV. All of that said, I saw this post when it originally came in. I notice no one has responded to it until now. I don't know about anyone else, but I know that I was offended when I read this. I know for myself, I wasn't sure how to take this when I read it. Maybe you should not assume that people on this list don't know what hot sparing is, or that ZFS just learned. Just a suggestion. -- "You can choose your friends, you can choose the deals." - Equity Private "If Linux is faster, it's a Solaris bug." - Phil Harman Blog - http://whatderass.blogspot.com/ Twitter - @khyron4eva
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