How should I config striping of 32 disks?

[Jeong Jin-wook]

System:SD32
hpux:11.11
disk:EMC 13G*32LUN
fc card*6
application:oracle 9i
customer will use lvol for db file system.

I will create vg01 with 32LUN and make 4 lvols with 104G.
I think 8LUN are needed for 1 lvol.
Customer wants striping to improve performance.
What is the best way to stripe?
(stripes(-i) and stripe size(-I)?)

[Keith Bryson]

Hi Jeong

I would create the VG first with the first 8 LUNS, then use lvcreate -L {LVOL_SIZE} -i 8 -I {STRIPE_SIZE} /dev/{VG_NAME}. Your LVOL_SIZE will be the total of [LUN physical extents * VG physical extent size] for all 8 LUNS added together (get your calculator out!). STRIPE_SIZE is dictated by Oracle. I seem to remember 64 being adequate.

Then add the next 8 LUNS, repeat the lvcreate etc.

Keith

[Keith Bryson]

To detail further (my response was hard-going!!):

Create the VG with the 8 LUNS.
Do 'vgdisplay -v /dev/{VG_NAME}'
Make a note of "PE Size (MBytes)" and "Total PE" for each listed Physical volume (LUN).

Multiply these 2 figures, note the answer.
Do that for each LUN.
Add all 8 answers together.

Use the final figure in the lvcreate:
lvcreate -L {FINAL_FIGURE} -i 8 -I 64 /dev/{VGNAME}

Good luck! Keith

[Devender Khatana]

Hi,

We have similar setup but with HP storage instead. We are using Veritas Volume Manager3.5. Here we have created volumes using a strip size of 4096 & 32 Columns. This is also used for production DB Server. The LUN size is also 13 GB only. But we are using Oracle 8i alongwith SAP R/3.

HTH,
Devender

[Victor BERRIDGE]

Hi,
A pity not 36 LUNs, or can you get that extra?
Why?
Having 6 FC HBAs it would have been for best load balancing to stripe across the 6 (or multiple) and of course the best would be having at each time disks from different arrays (6 disks per array)X 6 or (3 /array)X12 etc...

My 2 cents
All the best
Victor

[Victor BERRIDGE]

Definitely if performances is what you are after I would add 4 extra LUNS, and stripe on all 36 disks spread on you 6 HBAs I=64.
This avoids you to think about striping on which disks for which lvol and leaves you after your 4 lvols created with 50 GB spare to finely extend to need.

All the best
Victor

[Keith Bryson]

When you finally get the LVs configured, don't forget to use vgextend to add the alternate paths (I assume you see the same LUN through different FC controllers). Then use 'pvchange -s /dev/dsk/{device}' to force alternate access to different paths for each LUN (vgdisplay -v {VG} will show the primary and alternate physical volume paths). That will help performance too, as you aren't hitting the same controller.

Keith

[Jeff Schussele]

Uhhmmmm....the real question should be...
Do you *really* want to put *all* 32 LUNs in a single VG?
EVEN if this is for Oracle DB space, there's NO rule that says they have to all be in the same VG.
I've had HW and SW problems that have whacked an entire VG. I'd hate to have to wait for 416 GB to restore from tape.

My $0.02,
Jeff

[Victor BERRIDGE]

I agree with you Jeff, I would have created 6VG with 6 LUN each (each LUN from a different EMC array or whatever they call it) but that doesnt let you make a lvol of 104GB...
But like you I got once a few fs corruption with file systems of > 100GB and restoration is terribly long compared to smaller sized...


All the best
Victor