Of course it would be preferable to leave this in the admin's hand via
system-wide LVM configuration. This would also give Tom the flexibility
for his setup. However, I don't know a way to achieve striping in LVM
without using the -i option. raid_stripe_all_devices=1 does not achieve
that result, cf. https://serverfault.com/questions/849088
If someone knows how to configure striping in LVM, then I'll be happy to
write a few lines for the Proxmox documentation or wiki. If not, using
-i seems to be the only way to achieve striping.
Basically, we are discussing to change the current behaviour from "use 1
stripe" to "use <number of pvs> stripes". The latter option seems to
make a lot more sense to me, although I can see that there are special
setups requiring exactly one stripe.
I see three options:
1) We find a way to configure that using LVM; I'll contribute documentation
2) We add a "-stripes" option to pct create, with options
0 ==> old behaviour (no -i)
n>0 ==> n stripes
auto ==> number of pvs
3) Like 2), but define it as an option of the PVE storage
(/etc/pve/storage.cfg)
Option 3) would probably be beyond my humble Perl coding skills, but I
would happily contribute to 1) or 2)
What do you think?
Martin
Am 27.07.2017 um 11:54 schrieb Wolfgang Bumiller:
LVM seems to do a sane thing by default here, and can be configured to
do what you're doing via lvm.conf AFAICT.
From lvcreate(1):
| In order to stripe across all PVs of the VG if the -i argument is
| omitted, set raid_stripe_all_devices=1 in the allocation section of
| lvm.conf (5)
And the default behavior:
| RAID 0 will stripe across 2 devices, RAID 4/5 across 3 PVs, RAID 6
| across 5 PVs and RAID 10 across 4 PVs in the volume group if the -i
| argument is omitted.
I'd argue this should be left to the user to configure via lvm.conf
then.
In any case, two comments on the patch itself:
You should disable line-wrapping in your mail client when sending
patches as it cannot be applied via `git am` currently.
And I think I'd prefer adding the "pv_count" option to `lvm_vgs()`
instead of adding a separate function for it.
On Wed, Jul 26, 2017 at 08:47:03PM +0200, Martin Lablans wrote:
Signed-off-by: Martin Lablans <c...@martin.lablans.de>
---
PVE/Storage/LVMPlugin.pm | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/PVE/Storage/LVMPlugin.pm b/PVE/Storage/LVMPlugin.pm
index 9633e4c..cfb18e4 100644
--- a/PVE/Storage/LVMPlugin.pm
+++ b/PVE/Storage/LVMPlugin.pm
@@ -285,13 +285,30 @@ sub alloc_image {
$name = lvm_find_free_diskname(lvm_list_volumes($vg), $vg, $storeid,
$vmid)
if !$name;
- my $cmd = ['/sbin/lvcreate', '-aly', '--addtag', "pve-vm-$vmid",
'--size', "${size}k", '--name', $name, $vg];
+ my $num_pvs = lvm_find_number_of_pv($vg);
+
+ my $cmd = ['/sbin/lvcreate', '-aly', '-i', $num_pvs, '--addtag',
"pve-vm-$vmid", '--size', "${size}k", '--name', $name, $vg];
run_command($cmd, errmsg => "lvcreate '$vg/pve-vm-$vmid' error");
return $name;
}
+sub lvm_find_number_of_pv {
+ my ($vg) = @_;
+
+ my $cmd = ['/sbin/vgs', $vg, '--noheadings', '--unbuffered',
'--nosuffix', '--options', 'pv_count'];
+
+ my $ret;
+
+ run_command($cmd, errmsg => "lvm_find_number_of_pv: Cannot determine
number of PVs for VG $vg", outfunc => sub {
+ my $line = shift;
+ $ret = trim($line);
+ });
+
+ return $ret;
+}
+
sub free_image {
my ($class, $storeid, $scfg, $volname, $isBase) = @_;
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