--- Begin Message ---
Current cstream implementation is pretty slow, even without throttling.
use blkdiscard --zeroout instead when storage support it,
which is a few magnitudes faster.
Another benefit is that blkdiscard is skipping already zeroed block, so for
empty
temp images like snapshot, is pretty fast.
blkdiscard don't have throttling like cstream, but we can tune the step size
of zeroes pushed to the storage.
I'm using 32MB stepsize by default , like ovirt, where it seem to be the best
balance between speed and load.
https://github.com/oVirt/vdsm/commit/79f1d79058aad863ca4b6672d4a5ce2be8e48986
but it can be reduce with "saferemove_stepsize" option.
stepsize is also autoreduce to sysfs write_zeroes_max_bytes, which is the
maximum
zeroing batch supported by the storage
test with a 100G volume (empty):
time /usr/bin/cstream -i /dev/zero -o /dev/test/vm-100-disk-0.qcow2 -T 10 -v 1
-b 1048576
13561233408 B 12.6 GB 10.00 s 1356062979 B/s 1.26 GB/s
26021462016 B 24.2 GB 20.00 s 1301029969 B/s 1.21 GB/s
38585499648 B 35.9 GB 30.00 s 1286135343 B/s 1.20 GB/s
50998542336 B 47.5 GB 40.00 s 1274925312 B/s 1.19 GB/s
63702765568 B 59.3 GB 50.00 s 1274009877 B/s 1.19 GB/s
76721885184 B 71.5 GB 60.00 s 1278640698 B/s 1.19 GB/s
89126539264 B 83.0 GB 70.00 s 1273178488 B/s 1.19 GB/s
101666459648 B 94.7 GB 80.00 s 1270779024 B/s 1.18 GB/s
107390959616 B 100.0 GB 84.39 s 1272531142 B/s 1.19 GB/s
write: No space left on device
real 1m24.394s
user 0m0.171s
sys 1m24.052s
time blkdiscard --zeroout /dev/test/vm-100-disk-0.qcow2 -v
/dev/test/vm-100-disk-0.qcow2: Zero-filled 107390959616 bytes from the offset 0
real 0m3.641s
user 0m0.001s
sys 0m3.433s
test with a 100G volume with random data:
time blkdiscard --zeroout /dev/test/vm-100-disk-0.qcow2 -v
/dev/test/vm-112-disk-1: Zero-filled 4764729344 bytes from the offset 0
/dev/test/vm-112-disk-1: Zero-filled 4664066048 bytes from the offset 4764729344
/dev/test/vm-112-disk-1: Zero-filled 4831838208 bytes from the offset 9428795392
/dev/test/vm-112-disk-1: Zero-filled 4831838208 bytes from the offset
14260633600
/dev/test/vm-112-disk-1: Zero-filled 4831838208 bytes from the offset
19092471808
/dev/test/vm-112-disk-1: Zero-filled 4865392640 bytes from the offset
23924310016
/dev/test/vm-112-disk-1: Zero-filled 4596957184 bytes from the offset
28789702656
/dev/test/vm-112-disk-1: Zero-filled 4731174912 bytes from the offset
33386659840
/dev/test/vm-112-disk-1: Zero-filled 4294967296 bytes from the offset
38117834752
/dev/test/vm-112-disk-1: Zero-filled 4664066048 bytes from the offset
42412802048
/dev/test/vm-112-disk-1: Zero-filled 4697620480 bytes from the offset
47076868096
/dev/test/vm-112-disk-1: Zero-filled 4664066048 bytes from the offset
51774488576
/dev/test/vm-112-disk-1: Zero-filled 4261412864 bytes from the offset
56438554624
/dev/test/vm-112-disk-1: Zero-filled 4362076160 bytes from the offset
60699967488
/dev/test/vm-112-disk-1: Zero-filled 4127195136 bytes from the offset
65062043648
/dev/test/vm-112-disk-1: Zero-filled 4328521728 bytes from the offset
69189238784
/dev/test/vm-112-disk-1: Zero-filled 4731174912 bytes from the offset
73517760512
/dev/test/vm-112-disk-1: Zero-filled 4026531840 bytes from the offset
78248935424
/dev/test/vm-112-disk-1: Zero-filled 4194304000 bytes from the offset
82275467264
/dev/test/vm-112-disk-1: Zero-filled 4664066048 bytes from the offset
86469771264
/dev/test/vm-112-disk-1: Zero-filled 4395630592 bytes from the offset
91133837312
/dev/test/vm-112-disk-1: Zero-filled 3623878656 bytes from the offset
95529467904
/dev/test/vm-112-disk-1: Zero-filled 4462739456 bytes from the offset
99153346560
/dev/test/vm-112-disk-1: Zero-filled 3758096384 bytes from the offset
103616086016
real 0m23.969s
user 0m0.030s
sys 0m0.144s
Signed-off-by: Alexandre Derumier <[email protected]>
---
src/PVE/Storage/LVMPlugin.pm | 76 ++++++++++++++++++++++++++++++------
1 file changed, 65 insertions(+), 11 deletions(-)
diff --git a/src/PVE/Storage/LVMPlugin.pm b/src/PVE/Storage/LVMPlugin.pm
index 0416c9e..1eeeec0 100644
--- a/src/PVE/Storage/LVMPlugin.pm
+++ b/src/PVE/Storage/LVMPlugin.pm
@@ -3,10 +3,11 @@ package PVE::Storage::LVMPlugin;
use strict;
use warnings;
+use Cwd 'abs_path';
use File::Basename;
use IO::File;
-use PVE::Tools qw(run_command trim);
+use PVE::Tools qw(run_command file_read_firstline trim);
use PVE::Storage::Plugin;
use PVE::JSONSchema qw(get_standard_option);
@@ -284,23 +285,40 @@ my sub free_lvm_volumes {
my $vg = $scfg->{vgname};
- # we need to zero out LVM data for security reasons
- # and to allow thin provisioning
- my $zero_out_worker = sub {
- # wipe throughput up to 10MB/s by default; may be overwritten with
saferemove_throughput
- my $throughput = '-10485760';
- if ($scfg->{saferemove_throughput}) {
- $throughput = $scfg->{saferemove_throughput};
+ my $secure_delete_cmd = sub {
+ my ($lvmpath) = @_;
+
+ my $stepsize = $scfg->{'saferemove-stepsize'} // 32;
+ $stepsize = $stepsize * 1024 * 1024;
+
+ my $bdev = abs_path($lvmpath);
+
+ my $sysdir = undef;
+ if ($bdev && $bdev =~ m|^/dev/(dm-\d+)|) {
+ $sysdir = "/sys/block/$1";
+ } else {
+ warn "skip secure delete. lvm volume don't seem to be activated\n";
+ return;
}
- for my $name (@$volnames) {
- print "zero-out data on image $name (/dev/$vg/del-$name)\n";
+
+ my $write_zeroes_max_bytes =
+ file_read_firstline("$sysdir/queue/write_zeroes_max_bytes") // 0;
+ ($write_zeroes_max_bytes) = $write_zeroes_max_bytes =~ m/^(\d+)$/;
#untaint
+
+ if ($write_zeroes_max_bytes == 0) {
+ # if storage don't support write zeroes, we fallback to cstream
+ # wipe throughput up to 10MB/s by default; may be overwritten with
saferemove_throughput
+ my $throughput = '-10485760';
+ if ($scfg->{saferemove_throughput}) {
+ $throughput = $scfg->{saferemove_throughput};
+ }
my $cmd = [
'/usr/bin/cstream',
'-i',
'/dev/zero',
'-o',
- "/dev/$vg/del-$name",
+ $lvmpath,
'-T',
'10',
'-v',
@@ -318,6 +336,34 @@ my sub free_lvm_volumes {
};
warn $@ if $@;
+ } else {
+
+ # if the storage support write_zeroes but stepsize is too big,
+ # reduce the stepsize to the max possible
+ if ($write_zeroes_max_bytes > 0 && $stepsize >
$write_zeroes_max_bytes) {
+ warn "reduce stepsize to the maximum supported by the storage:"
+ . "$write_zeroes_max_bytes bytes\n";
+
+ $stepsize = $write_zeroes_max_bytes;
+ }
+
+ my $cmd =
+ ['/usr/sbin/blkdiscard', $lvmpath, '-v', '--zeroout',
'--step', "${stepsize}"];
+
+ eval { run_command($cmd); };
+ warn $@ if $@;
+ }
+ };
+
+ # we need to zero out LVM data for security reasons
+ # and to allow thin provisioning
+ my $zero_out_worker = sub {
+ for my $name (@$volnames) {
+ my $lvmpath = "/dev/$vg/del-$name";
+ print "zero-out data on image $name ($lvmpath)\n";
+
+ $secure_delete_cmd->($lvmpath);
+
$class->cluster_lock_storage(
$storeid,
$scfg->{shared},
@@ -376,6 +422,13 @@ sub properties {
description => "Zero-out data when removing LVs.",
type => 'boolean',
},
+ 'saferemove-stepsize' => {
+ description => "Wipe step size in MiB."
+ . "It will be capped to the maximum storage support.",
+ default => 32,
+ enum => [qw(1 2 4 8 16 32)],
+ type => 'integer',
+ },
saferemove_throughput => {
description => "Wipe throughput (cstream -t parameter value).",
type => 'string',
@@ -394,6 +447,7 @@ sub options {
shared => { optional => 1 },
disable => { optional => 1 },
saferemove => { optional => 1 },
+ 'saferemove-stepsize' => { optional => 1 },
saferemove_throughput => { optional => 1 },
content => { optional => 1 },
base => { fixed => 1, optional => 1 },
--
2.47.3
--- End Message ---
