gstripe on 7B4 - was: gmirror on 7B4

John Nielsen john at
Thu Jan 3 07:58:24 PST 2008

Quoting "Chris H." <>:
>> If you want specific advice for a specific scenario you can probably 
>> get it, but you'll have to supply some additional details. For 
>> instance I'm still not sure if this is a new install or an upgrade
> Both:
> I was wondering why gmirror wasn't an option during sysinstall (the
> creation, and installation to).
> Which begged the question - now that it's installed...
>> (even after re-reading the entire thread), or if da3 is the same 
>> size as da0-2. Doing what you describe below will blow away the 
>> existing contents of da3 and the other disks, and/or won't be 
>> allowed if anything on da3 is currently mounted/running. Also you 
>> should stop saying mirror if you mean stripe or JBOD. :)
> Quite right. Again, my bad. I'm sorry this became so convoluted. It seemed
> so clear at first. But as it started a question about gmirror, and my
> almost immediate discovery that gmirror doesn't do RAID0, as I required.
> Turned it into gstripe. I thought I had managed to make the transition
> smoothly. But as you effectively indicated, no dice. Sorry. :(
> Thank you *very* much for your informative, and thoughtful replies -
> and patience. :)
> OK, in the final analysis I've decided (now that it's (7B4) installed...)
> I'll just keep /boot, /root (and presumably /dev) on the already available
> and running install disk (da3).
> Then perform:
> # gstripe label -v -s 131072 bigstripe \
> /dev/da0 /dev/da1 /dev/da2
> # newfs -U /dev/stripe/bigstripe
> # mkdir /bigstripe
> # mount /dev/stripe/bigstripe /bigstripe
> # echo 'geom_stripe_load="YES"' >> /boot/loader.conf
> # echo '/dev/stripe/bigstripe /bigstripe ufs rw 2 2' >> /etc/fstab

Good up to here. Now you still have your running system and existing 
partitions on da3, and a new empty large raid0 volume mounted on 
/bigstripe. Before continuing, you should ask yourself (and perhaps 
tell the rest of us) what exactly do you want to use all of that space 
for? da3 is probably large enough for the OS itself, and while it's not 
redundant at least you have better odds of not losing your OS if a 
drive fails with this setup.

> # cd /var
> # tar cf - . | (cd /bigstripe; tar xvf -
> and repeating the above two lines for
> /bin, /compat, /dist, /entropy, /etc, /lib, /libexec,
> /media, /mnt, /proc, /rescue, /sbin, /sys, /tmp, and /usr

That will get your files moved, but what are you trying to accomplish here?

> moving and remaking /home. Then deleting and re-creating
> the above (/bin, /compat, etc...).

How do you propose to re-create them if they've been moved to a 
different filesystem? At best you can create symlinks to them which 
will usually work, but in this case I don't see a reason to go that 

> Then modify /etc/fstab
> to read /dev/stripe/bigstripe / ufs rw 2 2

And this is the big question mark/red flag. If you get rid of da3 then 
you won't be able to boot, and if you're keeping it anyway then why not 
use it? If you really want to do this you should use dump/restore 
instead of tar above and do the entire root filesystem (by which I mean 
"/" and not just "/root"), then be careful to always update /boot and 
/etc on da3 any time you update the system. Or in other words, you're 
asking for trouble.

> unmount /bigstripe

That should be umount, although you should probably just reboot with 
the new fstab if that's what you really want.

> mount /

Same as above.

> Done. Yes?


> Maybe I'm overestimating the FreeBSD file system. But this
> seems plausible.

FreeBSD can handle it and you're definitely moving in the direction of 
a workable setup here, but you may have gotten a bit carried away. A 
better option might be to just move one mountpoint (such as /var) over 
to the stripe volume by using dump/restore, then update fstab so it 
gets mounted from the new location. If you want to move other 
directories (such as /tmp or /home or even /usr) to the new volume you 
can do so, you'll just need to create symlinks to their new locations.

If this is or was a new install you may want to start over and re-do 
your partitioning with the end goal in mind (so you don't have unused 
space or partitions on da3, for instance).

> Thanks to everyones time, consideration (and patience).



>>> For the record, FSTAB (on da3):
>>> /dev/da3s1b
>>> none (swap)
>>> /dev/da3s1a
>>> /
>>> /dev/da3s1d
>>> /var
>>> Thanks for your response.
>>> Chris
> A *little* history, perhaps helps context...
> ---8<---snip---8<---
>>>>>> OK, my mistake...
>>>>>> Seems for my application (RAID0), *gstripe* is what I should
>>>>>> be using.
>>>>>> Q: But RAID0 provides 0 redundancy. How will you cope with data loss?
>>>>>> A: Complete backups occur twice daily and I (we) use IP RAID0 -
>>>>>> eg; 2 different servers have/provide the same data, and the DNS provides
>>>>>> "round-robin". Thereby spreading the requests roughly equal across
>>>>>> both servers.
>>>>>> So, given my new found knowledge. I felt I should probably ask before
>>>>>> potentially clobbering (breaking) the server I'll be attempting this on.
>>>>>> Will the following accomplish my goal?
>>>>>> Current setup:
>>>>>> /dev indicates the following:
>>>>>> da0, da0c, da0cs1, da0s1, da0s1c
>>>>>> da1, da1c, da1cs1, da1s1, da1s1c
>>>>>> da2, da2c, da2cs1, da2s1, da2s1c
>>>>>> ...and the following, which FreeBSD is installed on:
>>>>>> da3, da3s1, da3s1a, da3s1b, da3s1c, da3s1d
>>>>>> All drives are of same size/make/model.
>>>>>> Given the above, I intend to issue the following:
>>>>>> # gstripe label -v -s 131072 bigstripe \
>>>>>> /dev/da0 /dev/da1 /dev/da2 /dev/da3
>>>>>> # newfs -U /dev/stripe/bigstripe
>>>>>> # mount /dev/stripe/bigstripe /bigstripe
>>>>>> # echo 'geom_stripe_load="YES"' >> /boot/loader.conf
>>>>>> # echo '/dev/stripe/bigstripe /bigstripe ufs rw 2 2' >> /etc/fstab
>>>>> Yes, this should be fine (though you may need to do a "gstripe 
>>>>> load" near the beginning).
>>>>>> Or do/should I issue:
>>>>>> # gconcat label -v extradisks /dev/da0 /dev/da1 /dev/da2
>>>>>> # gstripe label -v bigstripe /dev/da3 /dev/concat/extradisks
>>>>>> # bsdlabel -wB /dev/stripe/bigstripe
>>>>>> # newfs -U /dev/stripe/bigstripe
>>>>>> # mount /dev/stripe/bigstripe /bigstripe
>>>>> No, assuming the disks are (roughly) the same size there's no 
>>>>> reason to use gconcat, and in this case doing so will likely hurt 
>>>>> performance in addition to adding complexity. gconcat is 
>>>>> generally just for JBOD-type scenarios and it sounds like you're 
>>>>> after RAID0 which is what gstripe is for.
>>>>> JN
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