archive mirror
 help / color / mirror / Atom feed
From: Zdenek Kabelac <>
To: LVM general discussion and development <>,
	Gang He <>
Subject: Re: [linux-lvm] About --mirrorlog mirrored option in the latest lvm2
Date: Wed, 31 Oct 2018 11:08:34 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Dne 31. 10. 18 v 8:18 Gang He napsal(a):
> Hello List,
> As you know, in the past versions(e.g. v2.02.120), lvcreate supports creating a mirror type LV with "--mirrorlog mirrored" option,
> But in the latest versions(e.g. v2.02.180), lvm2 says "mirrored is a persistent log that is itself mirrored, but should be avoided. Instead, use the raid1 type for log redundancy."
> Then,  my questions are as below,
> 1)The latest lvm2 does not allow creating this kind of LV, or just not recommended?
> In my test environment, it looks that LVM2 can not create this kind of LV.
> tb0307-nd1:/ # lvcreate --type mirror -m1 --mirrorlog mirrored -L 2G -n mirr-lv cluster-vg2
>    Log type, "mirrored", is unavailable to cluster mirrors.
> 2)If we can not create this kind of LV, how can we migrate these existing LVs after we upgrade LVM2 to the latest version (e.g. v2.02.180)?
> e.g. we need to convert this kind of LV to "RAID1 type LV, I want to know if there is a suggested guide for this scenario.


In general -  users should be creating '--type raid1'   mirrors - user get 
this type automatically when asks for a mirrored LV for long time already.
(lvcreate -m1)  (and old --type mirror only when explicitly set with --type 

Mirrored log type had several mostly unfixable design issues - thus it's 
support is marked as deprecated - you still can activate it - but you cannot 
create it as a new device anymore.

In practices users should convert type 'raid1' types  (via lvconvert) - since 
its support for log per leg is believed to be better approach and it's also 

The only remaining place where the old mirror does not have yet replacement is 
clustered mirror with cmirrord - so only here user should keep running old 
mirror type (but it's believed users are shifting to other technologies giving 
better performance i.e. gluster)


  reply	other threads:[~2018-10-31 10:08 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-31  7:18 [linux-lvm] About --mirrorlog mirrored option in the latest lvm2 Gang He
2018-10-31 10:08 ` Zdenek Kabelac [this message]
2018-10-31  8:28 Gang He

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).