[linux-lvm] Thin Pool Performance

[shankha <shankhabanerjee@gmail.com>]

Hi,
Please allow me to describe our setup.

1) 8 SSDS with a raid5 on top of it. Let us call the raid device : dev_raid5
2) We create a Volume Group on dev_raid5
3) We create a thin pool occupying 100% of the volume group.

We performed some experiments.

Our random write operations dropped  by half and there was significant
reduction for
other operations(sequential read, sequential write, random reads) as
well compared to native raid5

If you wish I can share the data with you.

We then changed our configuration from one POOL to 4 POOLS and were able to
get back to 80% of the performance (compared to native raid5).

To us it seems that the lvm metadata operations are the bottleneck.

Do you have any suggestions on how to get back the performance with lvm ?

LVM version:     2.02.130(2)-RHEL7 (2015-12-01)
Library version: 1.02.107-RHEL7 (2015-12-01)

Thanks