From 38256320e6ea5afafa750302d43c90e7f0a852fe Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Mon, 13 Jul 2009 14:52:50 +0200
Subject: [PATCH] Use full-stripe size in LVM growth
LVM has issues when growing stripped volumes, so it's best to specify
the growth in exact multiples of the full stripe size (as precise as
possible). For this we need to do a couple of changes:
- in LVM Attach(), we query additionally the VG extent size and the LV
stripe count; since this makes lvs return a (possibly) multi-line
output, we now split it into lines and only take the last one
- in LVM Grow(), we round up the increase in multiples of the full
stripe size
The patch also sets the correct target size in DRBD growth.
Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Olivier Tharan <olive@google.com>
---
lib/bdev.py | 49 +++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 41 insertions(+), 8 deletions(-)
diff --git a/lib/bdev.py b/lib/bdev.py
index 006e5e3cf..e5ae92225 100644
--- a/lib/bdev.py
+++ b/lib/bdev.py
@@ -299,7 +299,7 @@ class LogicalVolume(BlockDev):
self._vg_name, self._lv_name = unique_id
self.dev_path = "/dev/%s/%s" % (self._vg_name, self._lv_name)
self._degraded = True
- self.major = self.minor = None
+ self.major = self.minor = self.pe_size = self.stripe_count = None
self.Attach()
@classmethod
@@ -411,19 +411,30 @@ class LogicalVolume(BlockDev):
"""
self.attached = False
result = utils.RunCmd(["lvs", "--noheadings", "--separator=,",
- "-olv_attr,lv_kernel_major,lv_kernel_minor",
- self.dev_path])
+ "--units=m", "--nosuffix",
+ "-olv_attr,lv_kernel_major,lv_kernel_minor,"
+ "vg_extent_size,stripes", self.dev_path])
if result.failed:
logging.error("Can't find LV %s: %s, %s",
self.dev_path, result.fail_reason, result.output)
return False
- out = result.stdout.strip().rstrip(',')
+ # the output can (and will) have multiple lines for multi-segment
+ # LVs, as the 'stripes' parameter is a segment one, so we take
+ # only the last entry, which is the one we're interested in; note
+ # that with LVM2 anyway the 'stripes' value must be constant
+ # across segments, so this is a no-op actually
+ out = result.stdout.splitlines()
+ if not out: # totally empty result? splitlines() returns at least
+ # one line for any non-empty string
+ logging.error("Can't parse LVS output, no lines? Got '%s'", str(out))
+ return False
+ out = out[-1].strip().rstrip(',')
out = out.split(",")
- if len(out) != 3:
- logging.error("Can't parse LVS output, len(%s) != 3", str(out))
+ if len(out) != 5:
+ logging.error("Can't parse LVS output, len(%s) != 5", str(out))
return False
- status, major, minor = out[:3]
+ status, major, minor, pe_size, stripes = out
if len(status) != 6:
logging.error("lvs lv_attr is not 6 characters (%s)", status)
return False
@@ -434,8 +445,22 @@ class LogicalVolume(BlockDev):
except ValueError, err:
logging.error("lvs major/minor cannot be parsed: %s", str(err))
+ try:
+ pe_size = int(float(pe_size))
+ except (TypeError, ValueError), err:
+ logging.error("Can't parse vg extent size: %s", err)
+ return False
+
+ try:
+ stripes = int(stripes)
+ except (TypeError, ValueError), err:
+ logging.error("Can't parse the number of stripes: %s", err)
+ return False
+
self.major = major
self.minor = minor
+ self.pe_size = pe_size
+ self.stripe_count = stripes
self._degraded = status[0] == 'v' # virtual volume, i.e. doesn't backing
# storage
self.attached = True
@@ -554,6 +579,13 @@ class LogicalVolume(BlockDev):
"""Grow the logical volume.
"""
+ if self.pe_size is None or self.stripe_count is None:
+ if not self.Attach():
+ _ThrowError("Can't attach to LV during Grow()")
+ full_stripe_size = self.pe_size * self.stripe_count
+ rest = amount % full_stripe_size
+ if rest != 0:
+ amount += full_stripe_size - rest
# we try multiple algorithms since the 'best' ones might not have
# space available in the right place, but later ones might (since
# they have less constraints); also note that only recent LVM
@@ -1609,7 +1641,8 @@ class DRBD8(BaseDRBD):
if len(self._children) != 2 or None in self._children:
_ThrowError("drbd%d: cannot grow diskless device", self.minor)
self._children[0].Grow(amount)
- result = utils.RunCmd(["drbdsetup", self.dev_path, "resize"])
+ result = utils.RunCmd(["drbdsetup", self.dev_path, "resize", "-s",
+ "%dm" % (self.size + amount)])
if result.failed:
_ThrowError("drbd%d: resize failed: %s", self.minor, result.output)
--
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