[Novalug] LVM vs Partitions

James Ewing Cottrell 3rd JECottrell3@Comcast.NET
Tue Mar 16 02:03:03 EDT 2010


Bryan J. Smith wrote:
> 
> I mean, people remove hardware and then wonder why LVM is warning
> them.

But gee, all I removed was a *virtual* disk, not a *real* disk :)

I will admit to being a slow adopter of LVM, but just to clear up some 
of my prior rants, they weren't about LVM. LVM is pretty cool, and has 
pretty good documentation written on it.

I also share Bryan Smith's disdain of RAID-5. Every write requires N-2 
reads to fetch the appropriate data to compute the XOR Parity, and 2 
writes, so every disk is hit.

It probably gets even worse with atime, as those superblock (and copies 
of them) updates probably get written to all the disks as well.

Dedicated RAID boxen, and stuff like NetApp probably have their own 
special hardware to aid in the XOR'ing.

JIM



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