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Re: Advice on hardware server to use for small a dedicated data center

Miles Fidelman wrote: 
> Just to be clear... mdadm is NOT raid - it's an admin program for managing
> linux raid (md) devices.?? And then you need to worry about LVM (logical
> volume manager), and a network file system on top of them.

Just to be clear, you are being pedantic bordering on wrong here. This
is like saying "a hamburger is not ground beef patties, and then you
need to worry about vegetables and condiments".

mdadm is the administrative interface program for the kernel's md
subsystem. It is used generically as a synonym for "the kernel's
md subsystem" because for most people encountering them, they
are inextricably intertwined. 

The kernel's md subsystem manages RAID 0, 1, 4, 5, 6 and 10. It
also has a non-RAID linear mode, a container abstraction, and a
fault-simulation mode.

LVM is completely independent of the md subsystem, and can be
used with or without it. Some people love it. Some avoid it like
the plague -- oops. Some avoid it like rational people avoid the

Various network file systems are also completely independent of
the md subsystem.

ZFS is an integrated data storage system that presents N
filesystem and partition-equivalent views to the kernel. It is
independent of and an alternative to md and lvm. It offers a
semi-integrated NFS and CIFS export facility. Underneath, it
offers storage options including error-detection, compression, mirroring,
striping, RAID-5 and -6 style parity, read caching and write
caching. Only the error detection is mandatory.


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