Rodney D. Myers wrote:
> Linux-Fan wrote:
> > Rodney D. Myers wrote:
> > > Is there a debian specific mail list or online forum to get some
> > > help for a newbie setting up a raid storage device?
> > >
> > > I can find plenty of tips to get started, but things are not doing
> > > the exact thing(s) the online guides are showing.
It is all about using Debian so this mailing list is good. Lots of us
are using raid.
> > Also, if you manually want to create a RAID 1 of two partitions use
> >
> > # mdadm --create /dev/md0 --level=1 --raid-devices=2 \
> > /dev/sda1 /dev/sdb1
>
> Not attempting to install on a raid, but create a raid for storage
Linux-Fan's suggestion is a good one. If you are not using it for the
system then it is easier to get experience building raid yourself as
in the above example. François's suggestions were good too.
This is where I suggest that you think about using LVM in this
combination too. If your disks are large, and today's disks can be
very large, then I suggest setting up LVM on them and allocating
smaller portions at a time to the file system. It is much more
flexible than, say, having a 3T filesystem all in one place.
I would play with the above in order to get experience with raid.
Just setting things up, creating file systems, mounting them, checking
status. Then unmount and wipe clean and then try a different
configuration. Repeat a few times before you put it into service so
that you can understand what is happening.
To use LVM in the above start as suggested to create /dev/md0. Then
set it up for lvm with something like this:
Create a physical volume from the raid. (It places a signature there.)
pvcreate /dev/md0
Create a volume group using the physical volumes just created.
vgcreate vg0 /dev/md0
The status of the above can be seen using the status commands.
This will show summaries of space usage.
pvs
vgs
Allocate 100G to a logical volume to be used for a file system.
lvcreate -L100G -nfirst vg0
Make a file system on it. (/dev/vg0/first is same as /dev/mapper/vg0-first)
mkfs -t ext4 /dev/vg0/first
Mount it.
mkdir /srv/first
mount /dev/vg0/first /srv/first
I am just using "first" as an example. Assuming there will be a
"second". Name them according to your needs. I name mine after the
task. I have "root", "home", "var", "audio", "bak1", and so forth.
I always keep some disk space in reserve. If a partition needs more
space then it can be expanded online on the fly.
Extend a logical volume.
vgs
lvextend -L+25G /dev/vg0/first
resize2fs /dev/vg0/first
As long as you have free space available you can easily expand file
systems. As we recently discussed in this list a few days ago
shrinking a file system is not as simple. The simple advice is avoid
needing to shrink by planning ahead. But expanding one is easy and
reliable.
I advice to play with different configurations while the disks are new
and unused to gain experience. Easy to play now while there isn't
anything on the disks and you can try different things. Then choose a
configuration that works for you and move forward with it in real use.
Bob
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