Summary : Filesystems

Hi All,

       Thanks to Tony Walsh, GreenLand Simon, Andrew Stueve for there quick
replies & help..........
       Below given are the replies.............

My query was ...

----- Original Message -----
From: "Mangesh" <mangesh.v@xaalliance.com>
To: "sunmanager" <sunmanagers@sunmanagers.org>
Sent: Tuesday, April 30, 2002 11:37 AM
Subject: Filesystems


> Hi All,
>
>  I have a E-450 running Solaris 8. It is connected to the two T3 Sun
StorEdge
> ( T3-1 & T3-2 ). RAID 5 has been configured from the  hardware side i.e
T3.
> Both the T3 boxes are mirrored across each other with dual path to the
> server.
>  Now I have 4 filesystems which are layed on the T3-1, which have 7 disks
of
> 73 GB each. Each box having 2 controllers (dual path).
>  I have Veritas Volume manager 3.1.1 & Veritas Cluster 1.3.0.
>
>   I can see the T3-1 box through one controller, as one full chunk of disk
> space ( 7 X 73GB).
>   My vendor wants, that all the filesystems should be mapped to each
physical
> disk of the 7 disks.
>   for eg. if I have 5 filesystems, every filesystem should map to the
> different disk on the T3-1 ( 5 x 73GB ) i.e 5 filesystems, each of 73Gb
each.
>  Is it possible to create 5 filesystems on 5 different physical disk from
the
> T3-1.
>
> Any help or suggestions would be highly appreciated.
> Thanks in advance.
>
>
> Thanks & Regards
> Mangesh
> _______________________________________________
> sunmanagers mailing list
> sunmanagers@sunmanagers.org
> http://www.sunmanagers.org/mailman/listinfo/sunmanagers

Mangesh

The only way you can achieve dual pathing in this setup is to configure the
T3's
as a Partner Pair which you have not mentioned. This means that the 2 bricks
are
connected to each other via Copper Fibre cables across the back of the
arrays.

The T3 will NOT support more than 2 LUNs per tray (or brick) so you are not
able
to map individual disks to an individual LUN as you appear to want to do. If
you
want that kind of limitation then you need to have bought a D1000 (or
possibly an
A1000) so that individual drives are visible to the OS. A T3 has hardware
RAID
capabilities and therefore only presents the LUN to the OS (not drives) and
as
there is a logical limit of 2 LUNs per brick, you can only get 4 LUNs out of
this
configuration.

As there must be 9 drives of the same size in each T3 for a total of 18
drives,
what relevance do the 7 drives have to the 4 file systems you have?

In summary, it is NOT possible to create 5 physically separate filesystems
on 5
physically separate disk drives on any T3. Your best options are to define 1
or 2
LUNs per array in a Partner Pair configuration and then use VxVM to slice
them up
the way you want.

Regards Tony Walsh.

I hope this helps.


Mangesh,

I'm a little confused here: Setting up RAID 5 on each T3 and then RAID 1
between the two sounds a bit excessive, especially when each T3 is highly
redundant (dual power supplies etc). You seem to be using 14 disks to
protect the data held by 6 disks (an 8 disk overhead).

Personally I see RAID 5 as a poorman's mirror: It protects only against a
single disk failure, but is cheaper than full mirroring because less disks
are needed.

You already have plenty of disks, so I'd remove RAID 5 and simply mirror
between the two T3s. This will be more efficient both in terms of available
disk space and in terms of read/writes. It also maintains the ability to
keep runnning if you loose 1 of your T3s, or a combination of disks from
each (as long one disk from each mirror is maintained).

Hope this helps,

Simon


Your 'vendor' should go jump in a lake.  Your 'vendor' shouldn't get
involved in the filesystem locations.  Your 'vendor' is an idiot.

If you have mirrored T3 arrays, then your disk performance should be
outstanding.  Any write contention that the idiot is worried about is a
non-issue.  T3s have hardware the accelorates RAID5 to the point that
it's performance is as good as RAID0.  Mirroring the two T3s does take a
small performance hit on writes, but you more than make up for it in
reads.

The way you have things setup is great.  Tell your idiot vendor to do
his job and stop worrying about yours.  You set it up good.

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Thanks again

Regards
Mangesh.
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