Thinly provisioned LVM volumes offer more scalable snapshots than the
original LVM snapshots. Thinly provisioned snapshots use a single
shared pool of storage (aka thin-pool) so there is no need to require
the user to have configured "lvcreate_size_args" in the
yum-fs-snapshot.conf for them.
When inspecting an LVM volume we now record the LVM "segtype" in the
volume dict. is_thin_volume() was introduced to simplify checking
whether an LVM volume is thinly provisioned or not.
Signed-off-by: Mike Snitzer <msnitzer@fedoraproject.org>
---
docs/yum-fs-snapshot.conf.5 | 3 ++-
plugins/fs-snapshot/fs-snapshot.py | 32 ++++++++++++++++++++------------
2 files changed, 22 insertions(+), 13 deletions(-)
diff --git a/docs/yum-fs-snapshot.conf.5 b/docs/yum-fs-snapshot.conf.5
index a4b4f02..dc5c0c1 100644
--- a/docs/yum-fs-snapshot.conf.5
+++ b/docs/yum-fs-snapshot.conf.5
@@ -28,7 +28,8 @@ created for filesystems built on LVM logical volumes.
.IP lvcreate_size_args
This is the space delimited lvcreate argument list that is used to
specify the size of the snapshot LV. Valid lvcreate size options are -l
-or -L. If not specified then LVM snapshots will not be created.
+or -L. If not specified then LVM snapshots will not be created for
+volumes that are not thinly provisioned.
.SH AUTHOR
.RS
Josef Bacik <josef@toxicpanda.com>
diff --git a/plugins/fs-snapshot/fs-snapshot.py b/plugins/fs-snapshot/fs-snapshot.py
index 2a7c65d..7483c2d 100644
--- a/plugins/fs-snapshot/fs-snapshot.py
+++ b/plugins/fs-snapshot/fs-snapshot.py
@@ -62,6 +62,9 @@ def kernel_supports_dm_snapshot_merge():
dm_snapshot_merge_checked = 1
return dm_snapshot_merge_support
+def is_thin_volume(volume):
+ return volume["segtype"] == "thin"
+
def inspect_volume_lvm(conduit, volume):
"""
If volume is an LVM logical volume:
@@ -92,12 +95,14 @@ def inspect_volume_lvm(conduit, volume):
# Check if device is managed by lvm
# - FIXME filter out snapshot (and other) LVs; for now just rely
# on 'lvcreate' to prevent snapshots of unsupported LV types
- p = Popen(["/sbin/lvs", device], stdout=PIPE, stderr=PIPE)
+ p = Popen(["/sbin/lvs", "--noheadings", "-o", "segtype", device], stdout=PIPE, stderr=PIPE)
err = p.wait()
if not err:
+ volume["segtype"] = p.communicate()[0].strip()
+
# FIXME allow creating snapshot LVs even if kernel doesn't
# support snapshot-merge based system rollback? make configurable?
- if not kernel_supports_dm_snapshot_merge():
+ if not is_thin_volume(volume) and not kernel_supports_dm_snapshot_merge():
conduit.error(1, "fs-snapshot: skipping volume: %s, "
"kernel doesn't support snapshot-merge" % device)
return 0
@@ -223,16 +228,18 @@ def _create_lvm_snapshot(conduit, snapshot_tag, volume):
has enough free space to accommodate a snapshot LV.
- Also assumes user has configured 'lvcreate_size_args'.
"""
- lvcreate_size_args = conduit.confString('lvm', 'lvcreate_size_args',
- default=None)
- if not lvcreate_size_args:
- conduit.error(1, "fs-snapshot: 'lvcreate_size_args' was not provided "
- "in the '[lvm]' section of the config file")
- return 1
+ if not is_thin_volume(volume):
+ lvcreate_size_args = conduit.confString('lvm', 'lvcreate_size_args',
+ default=None)
- if not lvcreate_size_args.startswith("-L") and not lvcreate_size_args.startswith("-l"):
- conduit.error(1, "fs-snapshot: 'lvcreate_size_args' did not use -L or -l")
- return 1
+ if not lvcreate_size_args:
+ conduit.error(1, "fs-snapshot: 'lvcreate_size_args' was not provided "
+ "in the '[lvm]' section of the config file")
+ return 1
+
+ if not lvcreate_size_args.startswith("-L") and not lvcreate_size_args.startswith("-l"):
+ conduit.error(1, "fs-snapshot: 'lvcreate_size_args' did not use -L or -l")
+ return 1
device = volume["device"]
if device.count('/') != 3:
@@ -259,7 +266,8 @@ def _create_lvm_snapshot(conduit, snapshot_tag, volume):
(mntpnt, device, snap_lvname))
# Create snapshot LV
lvcreate_cmd = ["/sbin/lvcreate", "-s", "-n", snap_lvname]
- lvcreate_cmd.extend(lvcreate_size_args.split())
+ if not is_thin_volume(volume):
+ lvcreate_cmd.extend(lvcreate_size_args.split())
lvcreate_cmd.append(device)
p = Popen(lvcreate_cmd, stdout=PIPE, stderr=PIPE)
err = p.wait()
--
1.8.1
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