Re: Advice on hardware server to use for small a dedicated data center
Miles Fidelman wrote:
> On 7/1/20 7:04 AM, Reco wrote:
>
> > On Wed, Jul 01, 2020 at 08:49:09PM +1000, elvis wrote:
> > > On 1/7/20 4:51 am, Dan Ritter wrote:
[attributions snipped]
> > > > > No.. if you want to be pedantic, the proper terminology is "Linux Raid" or
> > > > > "md RAID."?? mdadm is one of several admin programs available
> > > > What are the others, please? (That will work on a modern system,
> > > > say, Debian stable or oldstable or unstable.)
> > > lvm does its own raid now too...
Elvis is correct here, but:
> > ... and it's not the mdraid, but entirely different kernel subsystem.
> > Last time I've checked it, they did not even implemented incremental
> > RAID assembly in LVM, meaning that you won't be able to use such array
> > if a single drive from LVM-based RAID will fail.
> > They've solved this problem in mdraid like 15 years ago.
Reco is also correct: lvm RAID is not mdadm RAID. And to further
confuse things, you can build an mdadm RAID and then put LVM on
top of it, but this is not the RAID that LVM manages.
> > But staying on-topic, I'm too very interested to hear about alternative
> > interfaces to mdraid, which do not involve mdadm. libblockdev2 does not
> > count, it's merely a wrapper.
>
> Sure looks like LVM raid make use of the same underlying md raid software as
> administered mdadm.
It doesn't.
> The info that LVM now includes some direct raid setup tools (that also make
> use of the underlying mdraid system), is new, and possibly useful.
It doesn't.
> Which does raise an interesting question:?? When the Debian installer gives
> the option to set up RAID volumes, does it use mdadm, or do it's own config,
> or use common libraries??? (Kind of arcane, but inquiring minds want to
> know.)
debian-installer calls partman; partman has a module called
partman-md; partman-md installs mdadm.udeb, which is a special
packaging of mdadm, produced by the Debian mdadm maintainers.
-dsr-
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