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List:       opensolaris-lvm-discuss
Subject:    Re: [lvm-discuss] Creating a STRIPE ( RAID-0 )
From:       "Paul Kraus" <pk1048 () gmail ! com>
Date:       2007-06-02 13:44:54
Message-ID: ddea9cf0706020644w20e4e1dal804b986869cc77fa () mail ! gmail ! com
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On 6/1/07, DeveloperSource <roover20@yahoo.com> wrote:

> I have the following disks:
>
> c7t2d0 c7t3d0 c7t4d0 c7t5d0 c7t8d0 c7t9d0 c8t2d0 c8t3d0 c8t4d0 c8t5d0 c8t8d0 c8t9d0
>
> Now I want to create a STRIPE with these disks first using UFS (SVM) and then Using ZFS.

I assume you mean the following:
1) create SVM/UFS stripe
2) use / test SVM/UFS stripe
3) delete SVM/UFS stripe
4) create ZFS stripe
5) test ZFS stripe

and not:
1) create SVM stripe
2) use SVM stripe for ZFS device

as that is NOT recommended.

> My question is, where should the state data base replicas located for optimal performance. ?
> Can some one list the commands to create STRIPE ( RAID-0 )

        The state database replica is written to when a change is made
to the SVM config and is generally read at boot time to populate the
md kernel module. Since so little i/o is done to the replicas, they
have almost no impact on performance.

        Assuming all 12 disk are identical, I would partition all of
them the same, with a very small (10MB or so) on slice 7 at the very
end of the disk and the remainder in slice 0. Then put metadb replicas
on slice 7 of three disks on controller 7 and three disk on controller
8 (loss of either controller will still give you enough replicas to
run, although you will have to manually delete enough so that you have
a majority and your data will be gone :-) I would probably put a
metadb on each drive (there isn't any real downside to that).

# metadb -a -f /dev/dsk/c7t2d0s7
for the first one, and then
# metadb -a /dev/dsk/c7t3d0s7
for all the rest

        You need to FORCE (-f) the first one as there are no existing
metadb replicas yet,

        Then to create your 12 column stripe (assuming it will be
metadevice d0 and consist of slice 0)
# metainit d0 1 12 c7t2d0s0 c7t3d0s0 c7t4d0s0 c7t5d0s0 c7t8d0s0
c7t9d0s0 c8t2d0s0 c8t3d0s0 c8t4d0s0 c8t5d0s0 c8t8d0s0 c8t9d0s0

        Although it would be better to put (do not include the ")
"d0 1 12 c7t2d0s0 c7t3d0s0 c7t4d0s0 c7t5d0s0 c7t8d0s0 c7t9d0s0
c8t2d0s0 c8t3d0s0 c8t4d0s0 c8t5d0s0 c8t8d0s0 c8t9d0s0"
in /etc/lvm/md.tab and then run
# metainit d0
to create the device

        This gives you and easy way to edit the config before
committing it and an easy way to recreate it if necessary.

        In terms of creating the ZFS stripe, I always use the Java ZFS
Administrator (https://localhost:6789)

-- 
Paul Kraus
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