[mythtv-users] Hard Drives that Actually Work?
phill_edwards at hotmail.com
Wed Dec 15 23:04:11 UTC 2004
> Asciimonster> Erroneus read data cannot be corrected in any way,
> Asciimonster> so that's all in the game. And that only corrupts a
> Asciimonster> few files while a complete hard disk crash just
> Asciimonster> looses you entire info. And if I understand you
> Asciimonster> correctly, RAID1 *does* protect you againt
> Asciimonster> that. Moreover the CRC checks on hard disk makes it
> Asciimonster> report an error before it get's the chance of
> Asciimonster> reading the wrong info.
>I have heard of a case when a cheap hard disk in a RAID1 setup failed,
>however it didn't report its failure. The hard disk just returned
>random data. Yes, CRC should protect against this, but it
>didn't. Maybe the hard disk didn't properly check the CRC. Or maybe it
>died to such an extent it could no longer control the IDE
>interface. What happened is a mystery. The computer read this random
>data from the faulty hard disk (not just file data, file system meta
>data too) and wrote it to the good hard disk. The result really was
>all information completely lost.
>1. This didn't happen to me, it is my recollection of events told be a
>2. You could argue that it was the fault of the hard disk not
> returning a failure error code - I agree.
I had a RAID mirror set up for a while on my home Internet
gateway/NAT/firewall box. In the end I turned off RAID in favour of setting
up a nightly backup onto the 2nd disk with rsync. That way if I accidentally
deleted/stuffed up something I could get the previous version back from the
backup disk. With RAID I couldn't do that. Sure, I could have backed up my
RAID disks but this ain't exactly a mission critical setup and I'd have to
buy yet more disk. The way I have it now I can lose 1 day's worth of data,
but I could modify the backup regime if that worried me.
I think it's good to question whether RAID is the best solution for a home
setup. Sometimes there's a simpler more useable solution that gives you more
of what you need for most scenarios.
I'll just go and put my flame suit on now...
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