That's the setup I have - and HATE it
Posted Jan 8, 2009 18:03 UTC (Thu) by khim
In reply to: Actually RAID/volume management is superlimited when not in filesystem...
Parent article: Btrfs aims for the mainline
Perhaps you want to be able to expand the alloted space, given
over to RAID1, RAID5, RAID10 etc?
I want to forget words
"RAID", "LVM" and related. Forever. I want sane options.
A. Store data cheaply (say... $0.10/GB) but unreliably: single disk failure
- and be ready to redownload/reinstall)
B. Store data reliably but expensively ($.40/GB): up to three disks
can fail without any problems
C. Some intermediate versions: cheap and reliable ($0.12/GB to $0.15/GB),
Ok with single disk failure (if it'll happen OS will of course
restore status quo if possible), but sloooooow (still much faster then
Just like filesystems were invented to make unnecessary manual manageent of
data on a single disk I want something to hide all this RAID/LVM/etc
stuff from me. Will it be btrfs or stack of other technologies - I don't
care as long as I have nice simple option list in "Save As..." dialog.
Couldn't that be done, by using LVM type block devices, used by
the RAID layer which is then exposed to filesystems, so they can
grow/shrink their capacity, as chunks of disk are (de)allocated to
May be. But then - it'll need huge, very complex
schemes to make it work well as whole. This is "microkernel vs monolitic
kernel" discussion all over again.
Call me a cynic if you like but pushing every feature you could
want into 1 layer, the filesystem, which should then become a generic
dynamic disk management system, would appear to become a very complicated
monolithic block of code. If sane implementations would then use generic
layers, then you're really back to where you started.
Why "monolithic block of code"??? I'm perfectly happy with separating of
functions - different filesystems are free to use the same implementation
of RAID, LVM, etc - if their authors decide it's the best way to do things.
Just as long as it's not exposed to userspace (or at least to user).
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