RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Bug 997613 - no longer able to create snapshot smaller then 3 chunks
Summary: no longer able to create snapshot smaller then 3 chunks
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: lvm2
Version: 7.0
Hardware: x86_64
OS: Linux
unspecified
low
Target Milestone: rc
: ---
Assignee: LVM and device-mapper development team
QA Contact: Cluster QE
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2013-08-15 19:17 UTC by Corey Marthaler
Modified: 2021-09-08 20:23 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2013-08-19 07:17:02 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Corey Marthaler 2013-08-15 19:17:30 UTC 
Description of problem:
The following test case no longer passes due to the new 3 chunk snapshot minimum. Is this expected going forward? Should all "small snap" test cases now be changed to be at least 3 chunks?

SCENARIO - [create_snap_on_1Kextent_vg]
Create a small snap on a VG with an extent size of only 1K
Recreating VG with smaller (1K) extent size
vgcreate -s 1K snapper /dev/vdg1
Creating small origin and snap
lvcreate -l 10 -n origin snapper
qalvm-01: lvcreate -l 10 -n small_snap1 -s /dev/snapper/origin
  Unable to create a snapshot smaller than 3 chunks (12 extents, 12.00 KiB).

[root@qalvm-01 ~]# lvcreate -l 10 -n small_snap1 -s /dev/snapper/origin
  Unable to create a snapshot smaller than 3 chunks (12 extents, 12.00 KiB).
[root@qalvm-01 ~]# lvcreate -l 11 -n small_snap1 -s /dev/snapper/origin
  Unable to create a snapshot smaller than 3 chunks (12 extents, 12.00 KiB).
[root@qalvm-01 ~]# lvcreate -l 12 -n small_snap1 -s /dev/snapper/origin
  Logical volume "small_snap1" created


Version-Release number of selected component (if applicable):
3.10.0-0.rc5.61.el7.x86_64
lvm2-2.02.101-0.122.el7    BUILT: Wed Aug 14 08:27:33 CDT 2013
lvm2-libs-2.02.101-0.122.el7    BUILT: Wed Aug 14 08:27:33 CDT 2013
lvm2-cluster-2.02.101-0.122.el7    BUILT: Wed Aug 14 08:27:33 CDT 2013
device-mapper-1.02.80-0.122.el7    BUILT: Wed Aug 14 08:27:33 CDT 2013
device-mapper-libs-1.02.80-0.122.el7    BUILT: Wed Aug 14 08:27:33 CDT 2013
device-mapper-event-1.02.80-0.122.el7    BUILT: Wed Aug 14 08:27:33 CDT 2013
device-mapper-event-libs-1.02.80-0.122.el7    BUILT: Wed Aug 14 08:27:33 CDT 2013
cmirror-2.02.101-0.122.el7    BUILT: Wed Aug 14 08:27:33 CDT 2013
Comment 1 Marian Csontos 2013-08-19 07:17:02 UTC 
Added by Upstream commit 59962d8d3e1c402da02f7bf1b09978f570fd09d5:

    snapshot: require 3 chunks for creation
    
    There is no point in creation of 2chunks snapshot,
    since the snapshot is invalidated immeditelly with the first write
    as there is no free chunk for COW blocks
    (2 chunks are used by the snap header and the 1st. metadata chunk).
    
    Enhance error message about the lowest usable size.

Update STS please.
Comment 2 Marian Csontos 2013-08-19 07:36:11 UTC 
Added by Upstream commit 59962d8d3e1c402da02f7bf1b09978f570fd09d5:

    snapshot: require 3 chunks for creation
    
    There is no point in creation of 2chunks snapshot,
    since the snapshot is invalidated immeditelly with the first write
    as there is no free chunk for COW blocks
    (2 chunks are used by the snap header and the 1st. metadata chunk).
    
    Enhance error message about the lowest usable size.

Update STS please.
Comment 3 Marian Csontos 2013-08-19 07:38:46 UTC 
Ignore duplicate comment #2. Seems like the change collided with itself...
Note You need to log in before you can comment on or make changes to this bug.