On 14/09/17 15:58, Brassow Jonathan wrote:
Seems strange on the surface. Would you mind posting the layout of each? ‘lvs -a -o +devices’
brassow
here is for LV created without -i, both times with & without
I supplied all ten(all that VG has) pvs as arguments to
lvcreate.
$ lvs -a -o +devices,stripes,stripe_size chenbro0.1
LV VG Attr LSize Pool
Origin Data% Meta% Move Log Cpy%Sync Convert
Devices #Str Stripe
raid0.A chenbro0.1 rwi-aor--- 21.18t
raid0.A_rimage_0(0),raid0.A_rimage_1(0) 2 16.00k
[raid0.A_rimage_0] chenbro0.1 iwi-aor--- 10.59t
/dev/sdak(0) 1 0
[raid0.A_rimage_0] chenbro0.1 iwi-aor--- 10.59t
/dev/sdam(0) 1 0
[raid0.A_rimage_0] chenbro0.1 iwi-aor--- 10.59t
/dev/sdao(0) 1 0
[raid0.A_rimage_0] chenbro0.1 iwi-aor--- 10.59t
/dev/sdaq(0) 1 0
[raid0.A_rimage_0] chenbro0.1 iwi-aor--- 10.59t
/dev/sdas(0) 1 0
[raid0.A_rimage_0] chenbro0.1 iwi-aor--- 10.59t
/dev/sdau(0) 1 0
[raid0.A_rimage_1] chenbro0.1 iwi-aor--- 10.59t
/dev/sdal(0) 1 0
[raid0.A_rimage_1] chenbro0.1 iwi-aor--- 10.59t
/dev/sdan(0) 1 0
[raid0.A_rimage_1] chenbro0.1 iwi-aor--- 10.59t
/dev/sdap(0) 1 0
[raid0.A_rimage_1] chenbro0.1 iwi-aor--- 10.59t
/dev/sdar(0) 1 0
[raid0.A_rimage_1] chenbro0.1 iwi-aor--- 10.59t
/dev/sdat(0) 1 0
[raid0.A_rimage_1] chenbro0.1 iwi-aor--- 10.59t
/dev/sdav(0) 1 0
I cannot remove this LV for a while thus will not be able to
recreate with -i for now, sorry.
On Sep 13, 2017, at 8:53 AM, lejeczek <peljasz@yahoo.co.uk> wrote:
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 phy devs.
$ 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 max_latency=719.409 ms
Yet when I say: this many stripes:
$ lvcreate -n raid0.A --type raid0 -I 16 -i 10 -l 97%pv
dbench:
...
Throughput 83.2822 MB/sec 20 clients 20 procs max_latency=816.027 ms
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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read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
.
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