From mboxrd@z Thu Jan  1 00:00:00 1970
From: Heinz Mauelshagen <heinzm@redhat.com>
Subject: Re: raid1 round-robin scheduler
Date: Thu, 19 Feb 2015 16:02:20 +0100
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References: <54E58F6A.9040108@clodo.ru>
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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?
>