ccdconfig and Linux mdadm

[Maciej Suszko]

Warren Block <wblock at wonkity.com> wrote:
> On Fri, 4 Jul 2014, Mark Felder wrote:
> 
> >
> > On Jul 3, 2014, at 15:35, Maciej Suszko <maciej at suszko.eu> wrote:
> >>
> >> 180mb.* files were created under Linux. Again I can say FreeBSD
> >> rocks! ... as usual :D
> >>
> >>
> >
> > Wow, this is excellent. I hope this doesn't get lost to the mailing
> > list archives...
> 
> Agreed!
> 
> I suspect this can also be done with gconcant and gstripe.  If so,
> I'm willing to add it as an example to the gconcat man page.


Indeed, it can :) Here are details what I just have checked:


root at fbsd:~ # gpart show ada{1,3}
=>     1  204799  ada1  MBR  (100M)
       1  204799     1  linux-raid  (100M)

=>     1  204799  ada3  MBR  (100M)
       1  204799     1  linux-raid  (100M)

root at fbsd:~ # file -s /dev/ada{1,3}s1
/dev/ada1s1: data
/dev/ada3s1: data

root at fbsd:~ # gnop create -o 520192 /dev/ada{1,3}s1

root at fbsd:~ # gstripe create -s 512K stripe0 /dev/ada1s1.nop /dev/ada3s1.nop

root at fbsd:~ # file -s /dev/stripe/stripe0 
/dev/stripe/stripe0: ReiserFS V3.6


root at fbsd:~ # mount -t reiserfs -o ro /dev/stripe/stripe0 nobackup
root at fbsd:~ # cd nobackup/ && ls -1
.reiserfs_priv
150mb.MD5
150mb.file

root at fbsd:~ # df -ht reiserfs
Filesystem             Size    Used   Avail Capacity  Mounted on
/dev/stripe/stripe0    199M    182M     17M    92%    /root/nobackup

root at fbsd:~/nobackup # gmd5sum -c 150mb.MD5 
150mb.file: OK


The only "magic" here is to create accurate nop device (this can be
found reading first few KB from device - in case of superblock v1.2).
I'm sure it can be automated. The next step is to create stripe with
the same stripe size as created in Linux.

I suggest someone to do more testing, for example creating md device in
Linux with ext3 filesystem, mounting that in FreeBSD, doing some
writes, checksums and going back to Linux - check all created files
against those sums.

> ccd and ccdconfig are really old, although the ccdconfig man page was 
> updated in October 2013.  The example could go there, but I'd really 
> rather update the more modern tools.

Your welcome to do so :)
-- 
regards, Maciej Suszko.
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