Re: [gentoo-user] Re: SOLVED: Recover from LVM errors? (Was: Re: Help - system reboots while compiling)

[Boyd Stephen Smith Jr.]

On Thursday 29 March 2007, Remy Blank <remy.blank@×××××.com> wrote 
about '[gentoo-user]  Re: SOLVED: Recover from LVM errors? (Was: Re: 
Help - system reboots while compiling)':
> Boyd Stephen Smith Jr. wrote:
> > Surely, a filesystem should not shy
> > away from sanity checks that can be done with little overhead besides
> > CPU time, but adding a checksum to each block might be a little
> > overkill.
>
> As long as performance is OK, I am willing to sacrifice the space for
> the per-block checksum.

Yeah, if It's a CRC32 that's only 4 bytes out of a 4k block.  .1% space 
overhead is paltry compared to the space cost of RAID-3/5/6.

Even if it's something longer with error correction as well as detection, 
like a Hamming code, I imagine it could be *very* useful.  Most 
checksums/checkdigits [e.g. CRC16/CRC32 or using any Crypo hash as a 
checksum] only do error detection, but the theory behind error correction 
has been around nearly as long, it's just more "expensive".  More layers 
of redundancy are generally a good thing.

> BTW, 10 drives? Nice setup!

The machine's hostname is "monster" for a reason. 2x Dual-Core Opteron 
275s, 2x NVidia 7800GTX (overclocked by BFG), 4G RAM, 10x 500G Hitachi's 
in 2x Chenbro 5-in-3 enclosures (in RAID6 = ~4TB usable space), 2x 74G 
Raptors in software RAID-0, Dell 1905FP + Dell 2407WFP, 7.1 sound, SATA 
DVD+/-RW drive, basically everything I could ever need.  Built it myself 
(well, with the help of my geek friends as well) in the 1st half of 2005, 
although I've added some to it since then (drives and monitor).

There's a pic and blog post about it on the drupal installation @ my 
domain, listed in my .sig.

-- 
Boyd Stephen Smith Jr.                     ,= ,-_-. =. 
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