[linux-lvm] raid & its stripes
peljasz at yahoo.co.uk
Wed Sep 13 13:53:58 UTC 2017
hi boys, girls
man page reads: -i ...This is equal to the number of
physical volumes to scatter the logical volume data....
I wonder, when I do not use -i while creating an LV with 10
$ lvcreate -n raid0.A --type raid0 -I 16 -l 97%pv
a dbench would show:
$ dbench -t 60 20
Throughput 112.309 MB/sec 20 clients 20 procs
Yet when I say: this many stripes:
$ lvcreate -n raid0.A --type raid0 -I 16 -i 10 -l 97%pv
Throughput 83.2822 MB/sec 20 clients 20 procs
And though the results would vary, xfs, a dbench for LV with
no -i as an argument(which LVM chooses then to be 2) would
always look better.
And I thought, as in the manual, always make stripes to go
to all phy devices.
Question - is there some "little" magic LVM does? And if yes
then how/what it is?
many thanks, L.
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