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HPUX 11.0: LVM Stripping Across Multiple Disks

 
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LG Porter
Frequent Advisor

HPUX 11.0: LVM Stripping Across Multiple Disks

I have a K580 server running HPUX 11.0 Presently I have a configured named vg03 containing 7 disks(c0t1d0, c0t2d0, c0t3d0, c1t0d0, c1t3d0, c2t0d0, c2t1d0, each disk is 8683 megs, Seagate ST39173WC). The PE Size (Mbytes) is 4 Megs for vg03. There is already one logical volume defined in the volume group(vg03)being used called lvol1 using only one of the disk (c1t0d0). I need to create a 48GB file system across the remaining 6 six disks.

Question: What is the correct command syntax or method for stripping across the remaining 6 six using the default strip size of 8kB? Can stripping be directed at a specific set of disks that are not being used in a volume group that already has logical volumes defined? Thanks
5 REPLIES 5
Stefan Farrelly
Honored Contributor
Solution

Re: HPUX 11.0: LVM Stripping Across Multiple Disks

The command would be;

lvcreate -L 48000 -i 6 -I 8 /dev/vg03

You will need all 6 remaining disks in vg03 to have the same number of free extents, and even then 48GB may be too big, you may need to reduce it slightly. lvcreate will automatically look for 6 disks in vg03 with enough space to divide 48GB evenly over them, if not the command wont run.
Im from Palmerston North, New Zealand, but somehow ended up in London...
Sundar_7
Honored Contributor

Re: HPUX 11.0: LVM Stripping Across Multiple Disks

Hi,

Lvcreate the LV with 0 bytes and then use lvextend..Lvextend will allow u to specify the disks.

But remmeber, with LVM and Mirror-UX/DX , only extend based mirrors are possible.

If u create a LV with -i option, as far as I know, you cant mirror it.

-- Sundar.
Learn What to do ,How to do and more importantly When to do ?
Dietmar Konermann
Honored Contributor

Re: HPUX 11.0: LVM Stripping Across Multiple Disks

# lvcreate -i 6 -I 8 vg03
# lvextend -L $((48*1024)) /dev/vg03/lvol2 /dev/dsk/c0t1d0 /dev/dsk/c0t2d0 /dev/dsk/c0t3d0 /dev/dsk/c1t3d0 /dev/dsk/c2t0d0 /dev/dsk/c2t1d0

Best regards...
Dietmar.
"Logic is the beginning of wisdom; not the end." -- Spock (Star Trek VI: The Undiscovered Country)
GK_5
Regular Advisor

Re: HPUX 11.0: LVM Stripping Across Multiple Disks

lvcreate -n lvol2 -L 48000 -i 6 -I 8 /dev/vg03

Should do it. Remember, when you do striping without mirroring or RAID5, you loose file system when you loose any of the disk.

-GK-
IT is great!
Todd McDaniel_1
Honored Contributor

Re: HPUX 11.0: LVM Stripping Across Multiple Disks

Just a few things to consider here.

I agree with GK. without mirroring of somekind you are doomed... unless you take frequent backups...

On my systems with striped disks, I have them on EMC symm frames where they are H/W mirrored... so any single disk failures are irrelevant.

I would strongly recommending striping and mirroring... If you can afford it I would get 6 more disks and create striped mirrored LVol...


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If your desire is to have a performance gain by striping you will get that, however, you will be vulnerable to a single disk out of 6 biting you in the backside...

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Also, since these are internal disks, you arent going to have the latency that you would have with disks that are attached. So, I doubt that you will see much of a performance gain with this configuration especially since they are internal disks and will be using the host cache and not an external cache like a DB would have on external disks in a EMC or HP/Compaq frame.

Unix, the other white meat.