Re: [pve-devel] [PATCH qemu-server] fix #3324: clone disk: use larger blocksize for EFI disk when possible

[Fabian Ebner <f.ebner@proxmox.com>]

Am 01.03.21 um 11:13 schrieb Stefan Reiter:
> On 3/1/21 11:06 AM, Fabian Ebner wrote:
>> Am 01.03.21 um 10:54 schrieb Stefan Reiter:
>>> On 3/1/21 10:42 AM, Fabian Ebner wrote:
>>>> Moving to Ceph is very slow when bs=1. Instead, use the biggest 
>>>> possible power
>>>> of two <= 1024. At the moment our EFI image sizes are multiples of 
>>>> 1024, so
>>>> just using 1024 wouldn't be a problem, but this feels more 
>>>> future-proof.
>>>>
>>>> Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
>>>> ---
>>>>
>>>> I did not see an way for 'qemu-img dd' to use a larger blocksize 
>>>> while still
>>>> specifying the exact total size if it is not a multiple of the 
>>>> blocksize.
>>>>
>>>
>>> Could it make sense to just set the block size equal to the image 
>>> size with count=1 ? Since the images will always be very small anyway...
>>>
>>
>> Note that AAVMF_VARS.fd is 64 MiB. Are blocksizes that big a good idea?
>>
> 
> That'd be too much, but the VARS file shouldn't be copied anyway? Only 
> the efidisk attached to the VM?
> 

AFAICT that's the file used for the EFI disk.

>>>>   PVE/QemuServer.pm | 10 +++++++++-
>>>>   1 file changed, 9 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
>>>> index f401baf..e579cdf 100644
>>>> --- a/PVE/QemuServer.pm
>>>> +++ b/PVE/QemuServer.pm
>>>> @@ -6991,7 +6991,15 @@ sub clone_disk {
>>>>           # that is given by the OVMF_VARS.fd
>>>>           my $src_path = PVE::Storage::path($storecfg, $drive->{file});
>>>>           my $dst_path = PVE::Storage::path($storecfg, $newvolid);
>>>> -        run_command(['qemu-img', 'dd', '-n', '-O', $dst_format, 
>>>> "bs=1", "count=$size",
>>>> +
>>>> +        # Ceph doesn't like too small blocksize, see bug #3324
>>>> +        my $bs = 1;
>>>> +        while ($bs < $size && $bs < 1024 && $size % $bs == 0) {
>>>> +            $bs *= 2;
>>>> +        }
>>>> +        my $count = $size / $bs;
>>>> +
>>>> +        run_command(['qemu-img', 'dd', '-n', '-O', $dst_format, 
>>>> "bs=$bs", "count=$count",
>>>>               "if=$src_path", "of=$dst_path"]);
>>>>           } else {
>>>>           qemu_img_convert($drive->{file}, $newvolid, $size, 
>>>> $snapname, $sparseinit);
>>>>