gmirror on 7B4

John Nielsen john at jnielsen.net
Wed Jan 2 08:53:56 PST 2008


Quoting "Chris H." <chris#@1command.com>:

> Quoting "Chris H." <chris#@1command.com>:
>
>> Hello,
>> I seem to remember a similar question being asked in the past. But never
> ---8<---snip---8<---
>> I had originally intended to create a raid mirror on the whole lot of HD's
>> during the install process. But I wasn't presented, nor could I find that
>> option during install. So, due to lack of time, pushed it off till later,
>> and simply installed onto the one HD. Now to my question(s)...
>>
>> Where is the option to create, and install to a gMIRRORED drive-set?
> ---8<---snip---8<---
>> 2) In my cases above, I'm interested in RAID-0 (mirroring for /volume/
>> not redundancy).
>>
>
> 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

> Thank you for all your time and consideration.
>
> Chris
>
> P.S. I know this is a bit noisy. I intend to keep it brief.
> Thank you for your understanding. :)
>
>> -- 
>> panic: kernel trap (ignored)
>>
>>
>>
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>
> -- 
> panic: kernel trap (ignored)
>
>
>
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