On 03/10/2015 12:55 PM, konstantin wrote:
19.02.2015 18:02, Heinz Mauelshagen пишет:
dm-mirror (i.e. "lvcreate --type mirror" or respective "dmsetup create
--table ...",
which is not the recommended raid1 layout any more) provides read
round-robin since long time.
You'd need an ancient kernel not to have it supported.
"raid1"/"raid10" (the recommended targets) , i.e. the md-raid based
mappings accessible via the dm-raid target
do read optimizations as well. Use "lvcreate --type raid1/raid10 ..." or
a respective dm table to set
those up. The former ("raid1") is the default in modern distributions
and configurable via setting
'mirror_segtype_default = "raid1"' in /etc/lvm/lvm.conf.
Heinz
On 02/19/2015 08:23 AM, konstantin wrote:
What version of the kernel should I use to get a round-robin read
implementation on LV raid1?
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I'm create raid1 lv with "lvcreate --type raid1 -m1 -L5G -n r1lv r1vg"
on vg with two physical devices:
lvs -a -o +devices
LV VG Attr LSize Pool Origin Data% Move Log
Copy% Convert Devices
r1lv r1vg rwi-a-m- 5.00g 100.00
r1lv_rimage_0(0),r1lv_rimage_1(0)
[r1lv_rimage_0] r1vg iwi-aor- 5.00g /dev/sda(1)
[r1lv_rimage_1] r1vg iwi-aor- 5.00g /dev/sdb(1)
[r1lv_rmeta_0] r1vg ewi-aor- 4.00m /dev/sda(0)
[r1lv_rmeta_1] r1vg ewi-aor- 4.00m /dev/sdb(0)
but, reading is only one of the devices (i see nmon live disk
utilization). There are solutions to ensure reading from the two devices?
How do you test?
Do you read from multiple threads?
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