Re: [PATCH 000 of 5] md: Introduction

From: Phillip Susi
Date: Thu Jan 19 2006 - 17:16:29 EST


I'm currently of the opinion that dm needs a raid5 and raid6 module added, then the user land lvm tools fixed to use them, and then you could use dm instead of md. The benefit being that dm pushes things like volume autodetection and management out of the kernel to user space where it belongs. But that's just my opinion...


I'm using dm at home because I have a sata hardware fakeraid raid-0 between two WD 10,000 rpm raptors, and the dmraid utility correctly recognizes that and configures device mapper to use it.


Neil Brown wrote:
Which bits?
Why?

My current opinion is that you should:

Use md for raid1, raid5, raid6 - anything with redundancy.
Use dm for multipath, crypto, linear, LVM, snapshot
Use either for raid0 (I don't think dm has particular advantages
for md or md over dm).

These can be mixed together quite effectively:
You can have dm/lvm over md/raid1 over dm/multipath
with no problems.

If there is functionality missing from any of these recommended
components, then make a noise about it, preferably but not necessarily
with code, and it will quite possibly be fixed.
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