Bug 199580

Summary:	Mirror device placement needs to be easier
Product:	Red Hat Enterprise Linux 5	Reporter:	Dean Jansa <djansa>
Component:	lvm2	Assignee:	Jonathan Earl Brassow <jbrassow>
Status:	CLOSED WONTFIX	QA Contact:	Corey Marthaler <cmarthal>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	5.4	CC:	agk, dwysocha, fweyns, heinzm, jbrassow, joe.thornber, mbroz, prockai, richard.f.dawson, robert.lawton
Target Milestone:	---	Keywords:	Documentation
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2010-05-19 14:17:04 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Dean Jansa 2006-07-20 15:37:56 UTC

Description of problem:

Using 3 pvs in a vg, attempt to create single leg mirror.  The logs and legs
are place on different devices each time the cmdline is run.

The user must be able to derterministicaly lay out a mirror.

[root@taft-04 ~]# lvcreate -m 1 -n mirror -L 2G vg /dev/sd[b,d]1 /dev/sdc1
  Logical volume "mirror" created
[root@taft-04 ~]# lvs -a -o +devices
  LV                VG   Attr   LSize Origin Snap%  Move Log         Copy%  Devices
  mirror            vg   mwi-a- 2.00G                    mirror_mlog  13.48
mirror_mimage_0(0),mirror_mimage_1(0)
 [mirror_mimage_0] vg   iwi-ao 2.00G                                      
/dev/sdd1(0)
 [mirror_mimage_1] vg   iwi-ao 2.00G                                      
/dev/sdb1(0)
 [mirror_mlog]     vg   lwi-ao 4.00M                                      
/dev/sdc1(0)
[root@taft-04 ~]# lvremove /dev/vg/mirror
Do you really want to remove active logical volume "mirror"? [y/n]: y
 Logical volume "mirror" successfully removed

[root@taft-04 ~]# lvcreate -m 1 -n mirror -L 2G vg /dev/sd[b,c]1 /dev/sdd1
 Logical volume "mirror" created
[root@taft-04 ~]# lvs -a -o +devices
 LV                VG   Attr   LSize Origin Snap%  Move Log         Copy%  Devices
 mirror            vg   mwi-a- 2.00G                    mirror_mlog  11.33
mirror_mimage_0(0),mirror_mimage_1(0)
 [mirror_mimage_0] vg   iwi-ao 2.00G                                      
/dev/sdd1(0)
 [mirror_mimage_1] vg   iwi-ao 2.00G                                      
/dev/sdb1(0)
 [mirror_mlog]     vg   lwi-ao 4.00M                                      
/dev/sdc1(0)

[root@taft-04 ~]# lvremove /dev/vg/mirror
Do you really want to remove active logical volume "mirror"? [y/n]: y
 Logical volume "mirror" successfully removed
[root@taft-04 ~]# lvcreate -m 1 -n mirror -L 2G vg /dev/sd[c,d]1 /dev/sdb1
 Logical volume "mirror" created
[root@taft-04 ~]# lvs -a -o +devices
 LV                VG   Attr   LSize Origin Snap%  Move Log         Copy%  Devices
 mirror            vg   mwi-a- 2.00G                    mirror_mlog  17.38
mirror_mimage_0(0),mirror_mimage_1(0)
 [mirror_mimage_0] vg   iwi-ao 2.00G                                      
/dev/sdd1(0)
 [mirror_mimage_1] vg   iwi-ao 2.00G                                      
/dev/sdc1(0)
 [mirror_mlog]     vg   lwi-ao 4.00M                                      
/dev/sdb1(0)

Comment 2 Kiersten (Kerri) Anderson 2006-09-06 20:06:18 UTC

Defect fix requires a change to lvm2 in base rhel release.  Moving this to the
RHEL product and updating to lvm2 component.  Will also update the tags for the
proposed release.

Comment 3 Kiersten (Kerri) Anderson 2006-09-06 20:08:46 UTC

Devel ACK

Comment 7 Jonathan Earl Brassow 2006-12-12 17:35:27 UTC

This does not require any kernel changes.

In fact, if the user is willing to take the time, you _can_ have deterministic
mirror creation.  What we want is the following:

lvcreate -m 1 -L 500M -n lv vg /dev/sda1 /dev/sdb1 /dev/sdc1

Where the trailing three arguments would represent the first mirror device, the
second mirror device, and the log.  You can, however, acheive this if you also
specify the extent count as follows:

lvcreate -m 1 -L 500M -n lv vg /dev/sda1:0-500 /dev/sdb1:0-499 /dev/sdc1:0

Comment 10 Jonathan Earl Brassow 2007-02-21 19:07:15 UTC

A simple approach suggested by agk is to do a two phased create.

# Create linear device
lvcreate -L <size> -n LV VG <1st set of devices>
# Upconvert to mirror
lvconvert -m1 VG/LV <2nd set of devices>

I've tested this and it works nicely.

Comment 11 Jonathan Earl Brassow 2007-02-21 20:26:30 UTC

Marking as modified given the above method for device placement.

Comment 12 Rob Kenna 2007-04-10 18:58:14 UTC

Removed Cluster flag since this is in RHEL proper; though needed for cluster mirror.

Comment 13 Rob Kenna 2007-04-12 14:15:07 UTC

Moved to 4.6 proposed.  pm-ack provided and other flags cleared.

Comment 14 Jonathan Earl Brassow 2007-04-16 17:17:04 UTC

This isn't going to make 4.6.  Still needs to be addressed though.

modified -> assigned

Comment 16 Michael Hideo 2007-06-06 04:46:36 UTC

Adding 'cc ecs-dev-list for tracking

Comment 17 Jonathan Earl Brassow 2007-07-27 16:09:10 UTC

*** Bug 234314 has been marked as a duplicate of this bug. ***

Comment 18 Michael Hideo 2007-10-23 02:51:59 UTC

Removing automation notification

Comment 19 Milan Broz 2010-05-18 08:59:18 UTC

Moving to RHEL5, is it only documentation or still some code changes?
Anyway, for RHEL4 are planned only approved fixes currently.

Comment 20 Jonathan Earl Brassow 2010-05-19 14:17:04 UTC

Won't fix in rhel5.  The solution will either have to be:
1) specifying the devices at the end of the command and specifically denoting the log devices via a trailing ':x' (e.g. /dev/sdd1:0)
2) create a linear device and follow-up with an lvconvert - specifying which devices to use at each step