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?
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WBR
Konstantin V. Krotov
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