mdadm usage: creating arrays with helpful names?
How do I create an array with a helpful name? i.e. "/dev/md/storage"?
The mdadm man page hints at this in the discussion of the --auto option in the ASSEMBLE MODE section, but doesn't clearly indicate how it's done.
Must I create the device nodes by hand first using MAKEDEV?
Thanks.
Quoted 7 lines · Richard Michael
How do I create an array with a helpful name? i.e. "
/dev/md/storage"?The mdadm man page hints at this in the discussion of the --auto option in the ASSEMBLE MODE section, but doesn't clearly indicate how it's done.
Must I create the device nodes by hand first using MAKEDEV?
Does this help?
http://linux-raid.osdl.org/index.php/Partitionable
David
A message that is not in the archive (sent off-list or not yet received): 20070627235739.GA30527@server
(back on list for google's benefit ;) and because there are some good questions and I don't know all the answers... )
Oh, and Neil 'cos there may be a bug ...
Quoted 6 lines · Richard Michael
Quoted 2 lines · David Greaves
Thanks. I didn't know this site existed (Googling even just 'mdadm' doesn't yield it in the first 100 results), and it's helpful.
Good ... I got permission to wikify the 'official' linux raid FAQ but it takes time (and motivation!) to update it :) Hopefully it will snowball as people who use it then contribute back <hint> ;)
As it becomes more valuable to people then more links will be created and Google will notice...
Quoted 3 lines
What if don't want a partitioned array? I simply want the name to be nicer than the
/dev/mdXor/dev/md/XXstyle. (p1 still gives me/dev/nicename/dev/nicename0, as your page indicates.)
--auto md
mdadm --create /dev/strawberry --auto md ...
root@ash:/tmp # mdadm --detail /dev/strawberry/dev/strawberry:
Version : 00.90.03
Creation Time : Thu Jun 28 08:25:06 2007
Raid Level : raid4
Quoted 4 lines
Also, when I use "--create
/dev/nicename--auto=p1" (for example), I also see/dev/md_d126created. Why? There is then a/sys/block/md_d126entry (presumably created by the md driver), but no/sys/block/nicenameentry. Why?
Not sure who creates this, mdadm or udev
The code isn't that hard to read and you sound like you'd follow it if you fancied a skim-read...
I too would expect that there should be a /sys/block/nicename - is this a bug Neil?
These options don't see a lot of use - I recently came across a bug in the --auto p<X> option...
Quoted 6 lines
Finally "--stop
/dev/nicename" doesn't remove any of the aforementioned /dev or /sys entries. I don't suppose that it should, but an mdadm command to do this would be helpful. So, how do I remove the oddly named /sys entries? (I removed the /dev entries with rm.) "man mdadm" indicates --stop releases all resources, but it doesn't (and probably shouldn't).
rm !
'--stop' with mdadm does release the 'resources', ie the components you used. It doesn't remove the array. There is no delete - I guess since an rm is just as effective unless you use a nicename...
Quoted 7 lines
[I think there should be a symmetry to the mdadm options "--create/--delete" and "--start/--stop". It's *convenient* --create also starts the array, but this conflates the issue a bit..]
I want to stop and completely remove all trace of the array. (Especially as I'm experimenting with this over loopback, and stuff hanging around irritates the lo driver.)
You're possibly mixing two things up here...
Releasing the resources with a --stop would let you re-use a lo device in another array. You don't _need_ --delete (or rm). However md does write superblocks to the components and *mdadm* warns you that the loopback has a valid superblock..
mdadm: /dev/loop1 appears to be part of a raid array:
level=raid4 devices=6 ctime=Thu Jun 21 09:46:27 2007
[hmm, I can see why you may think it's part of an 'active' array]
You could do mdadm --zero-superblock to clean the component or just say "yes" when mdadm asks you to continue.
see:
# mdadm --create /dev/strawberry --auto md --level=4 -n 6 /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5 /dev/loop6
mdadm: /dev/loop1 appears to be part of a raid array:
level=raid4 devices=6 ctime=Thu Jun 28 08:25:06 2007
<blah>
Continue creating array? yes
mdadm: array /dev/strawberry started.# mdadm --stop /dev/strawberry mdadm: stopped /dev/strawberry
# mdadm --create /dev/strawberry --auto md --level=4 -n 6 /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5 /dev/loop6
mdadm: /dev/loop1 appears to be part of a raid array:
level=raid4 devices=6 ctime=Thu Jun 28 09:07:29 2007
<blah>
Continue creating array? yes
mdadm: array /dev/strawberry started.David
Quoted 2 lines · David Greaves
(back on list for google's benefit ;) and because there are some good questions and I don't know all the answers... )
Thanks, I didn't realize I didn't 'reply-all' to stay on the list.
Quoted 2 lines
Hopefully it will snowball as people who use it then contribute back <hint> ;)
I will, I'm also keeping notes and changes to the man page. :)
Quoted 1 line
--auto md
Ah. Thanks for the example(s).
Quoted 5 lines
Quoted 4 lines
Also, when I use "--create
/dev/nicename--auto=p1" (for example), I also see/dev/md_d126created. Why? There is then a/sys/block/md_d126entry (presumably created by the md driver), but no/sys/block/nicenameentry. Why?Not sure who creates this, mdadm or udev
I'm guessing the kernel's md driver creates it; neither mdmadm nor udev (just as the kernel creates, for example, sd* disk entries in /sys, but udev creates the nice entries in /dev).
Quoted 2 lines
The code isn't that hard to read and you sound like you'd follow it if you fancied a skim-read...
I read it for the --create option to see who created /dev/mdXX. :) I'll take another look.
Thanks David.
Cheers.