topic Re: stripe size option on lvextend in Operating System - HP-UX

stripe size option on lvextend

TOMAS BERNABEU — Wed, 24 Apr 2002 13:32:22 GMT

what's the -I option (stripe size) ??
size stripe by disk or on the all disk ??

Re: stripe size option on lvextend

Uday_S_Ankolekar — Wed, 24 Apr 2002 13:37:01 GMT

Hi,
A logical volume (LV) can be set up to be 'striped' across multiple
disks, although the default condition is unstriped. When you stripe a
LV across multiple disks, each stripe can consist of as many or few
extents as you wish. The stripe size you choose will depend on the
contents of your LV and how the data is accessed

-USA..

Re: stripe size option on lvextend

Craig Rants — Wed, 24 Apr 2002 13:37:43 GMT

Tomas,
The lvextend command refers to a logical volume, so the striping will only take place on the the logical volume level. Thus it is possible to have a stripe on a disk, two disks, where the logical volume exists, thats were the stripe size applies.

GL,
C

Re: stripe size option on lvextend

S.K. Chan — Wed, 24 Apr 2002 13:40:58 GMT

You mean "-l" option ? That's size of extent specified in #extents vs "-L" which is size specified in MBs. Both applies to size of stripe if you choose to stripe.

Re: stripe size option on lvextend

TOMAS BERNABEU — Wed, 24 Apr 2002 13:41:29 GMT

example :

lvcreate -i 4 -I 64 .....

64 k by disk or 16+16+16+16 ??????

Re: stripe size option on lvextend

John Palmer — Wed, 24 Apr 2002 13:44:33 GMT

In your example, 64k on each disk.

Regards,
John

Re: stripe size option on lvextend

S.K. Chan — Wed, 24 Apr 2002 13:45:19 GMT

lvcreate then not lvextend ..

that would be 64K by disk

Re: stripe size option on lvextend

MANOJ SRIVASTAVA — Wed, 24 Apr 2002 13:45:25 GMT

Hi Tomas

Stripe is essentially a set of PE's which can be acroso different Physical disks which constitute a single volume group , ie if you have like 4 disks in a volume grouip you can cretae a logical volume which extednds across these four disks ie striped across , this make the response better as you can have same volume group acrss diffetn controllers. So in case you give a -I 4 option the lvol will start with the first disk and then use the second and so on.

Manoj Srivastava

Re: stripe size option on lvextend

MANOJ SRIVASTAVA — Wed, 24 Apr 2002 13:49:33 GMT

Tomas

Sorry for the typo it should read -i 4 , and the stripe size can be in multiples of PE , in you case yes 64K per disk .

Manoj Srivastava

Re: stripe size option on lvextend

Bill Slaughter — Wed, 24 Apr 2002 14:43:29 GMT

I am trying to get the best performance for my Oracle Database (Oracle Apps 10.7).

For a given physical I/O how much will LVM read in if we use the different strip sizes?

What is mean is:

1) Oracle app is reading a bock of data.

2a) LVM 64k stripe is used
2b) LVM 128K stripe size is used
2c) LVM "Distributed" 4MB PE size

Is LVM reading from disk any different amount based upon the stripe/distributed size?

Thanks