Messages in this thread | | | Date | Tue, 25 Aug 2009 18:17:02 -0700 (PDT) | From | david@lang ... | Subject | Re: [patch] document flash/RAID dangers |
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On Wed, 26 Aug 2009, Pavel Machek wrote:
> On Tue 2009-08-25 17:20:13, david@lang.hm wrote: >> On Wed, 26 Aug 2009, Pavel Machek wrote: >> >>> On Tue 2009-08-25 16:56:40, david@lang.hm wrote: >>>> On Wed, 26 Aug 2009, Pavel Machek wrote: >>>> >>>>> There are storage devices that high highly undesirable properties >>>>> when they are disconnected or suffer power failures while writes are >>>>> in progress; such devices include flash devices and MD RAID 4/5/6 >>>>> arrays. >>>> >>>> change this to say 'degraded MD RAID 4/5/6 arrays' >>>> >>>> also find out if DM RAID 4/5/6 arrays suffer the same problem (I strongly >>>> suspect that they do) >>> >>> I changed it to say MD/DM. >>> >>>> then you need to add a note that if the array becomes degraded before a >>>> scrub cycle happens previously hidden damage (that would have been >>>> repaired by the scrub) can surface. >>> >>> I'd prefer not to talk about scrubing and such details here. Better >>> leave warning here and point to MD documentation. >> >> I disagree with that, the way you are wording this makes it sound as if >> raid isn't worth it. if you are going to say that raid is risky you need >> to properly specify when it is risky > > Ok, would this help? I don't really want to go to scrubbing details. > > (*) Degraded array or single disk failure "near" the powerfail is > neccessary for this property of RAID arrays to bite.
that sounds reasonable
David Lang
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