gmirror on 7B4

John Nielsen lists at jnielsen.net
Wed Jan 2 08:53:57 PST 2008


I'm not sure I remember everything from earlier in this thread so I 
don't know if it's relevant, BUT you can't boot from a gstripe volume 
(or from a gconcat one AFAIK). Inferring from your fstab example below 
it doesn't sound like you intend to but I just wanted to be sure.

Quoting John Nielsen <john at jnielsen.net>:

> 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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>>
>
>
>




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