Migrating Linear LVM to Striped LVM
Hi all,
How are you all? I am just sharing my experience for an issue I have faced recently, hope I will get some good advice.
Recently I found some of our systems i/o is high. after gathering information, i got i am using Linear LVM it is so straight forward for writing data. I did not use Striped LVM for parallel data writing. My questions is,
- How I can implement Striped LVM?
- As I have already implemented Linear LVM, is it possible to migrate Linear LVM to Striped LVM without down time?
Please suggest if I am wrong.
Shyfur
Responses
Hello,
I'm sorry that you weren't able to get a response until now. I will try to address your questions, but if you'd like help with specific steps or analysis of the I/O performance problems, feel free to open a support case and we can gather information to look at it with more focus.
How I can implement Striped LVM?
You can create a striped logical volume by specifying -i (number of stripes) and -I (stripe size) in lvcreate. For example:
# lvcreate -L 10G -n lv1 -i 4 -I 64 myVG /dev/mapper/mpathb /dev/mapper/mpathc /dev/mapper/mpathd /dev/mapper/mpathe
That would create a 10 GiB volume with 4 stripes over the specified devices (which can be left out if you want lvm to decide where to put them), each consisting of 64KiB. Have a look at the lvcreate(8) man page for more information.
As I have already implemented Linear LVM, is it possible to migrate Linear LVM to Striped LVM without down time?
Unfortunately not. Only newly allocated space in a logical volume can be striped. You would need to back up your data and then recreate the volume with the proper striping, or create a new striped volume and move the data over to it.
Let us know if you have any questions.
Regards,
John Ruemker, RHCA
Senior Software Maintenance Engineer
Global Support Services
Red Hat, Inc.
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