[PATCH manager] ui: qemu: add detect zeroes disk option

[PATCH manager] ui: qemu: add detect zeroes disk option

[Lukas Sichert]

When discard is enabled, qemu-server defaults to `detect-zeroes=unmap`.
This can have a significant performance impact for zero writes on some
setups, while users might still want to keep guest discard/TRIM support
enabled.

Allow configuring the option independently so discard can stay enabled
while zero detection is disabled. Persist the checkbox state explicitly,
as the backend treats an absent value as the default-enabled behavior.

Signed-off-by: Lukas Sichert <l.sichert@proxmox.com>
---
 www/manager6/qemu/HDEdit.js | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/www/manager6/qemu/HDEdit.js b/www/manager6/qemu/HDEdit.js
index 1bb2bfda..d1d1b0fa 100644
--- a/www/manager6/qemu/HDEdit.js
+++ b/www/manager6/qemu/HDEdit.js
@@ -96,6 +96,7 @@ Ext.define('PVE.qemu.HDInputPanel', {
         PVE.Utils.propertyStringSet(me.drive, values.readOnly, 'ro', 'on');
         PVE.Utils.propertyStringSet(me.drive, values.cache, 'cache');
         PVE.Utils.propertyStringSet(me.drive, values.aio, 'aio');
+        me.drive.detect_zeroes = values.detect_zeroes ? 1 : 0;
 
         ['mbps_rd', 'mbps_wr', 'iops_rd', 'iops_wr'].forEach((name) => {
             let burst_name = `${name}_max`;
@@ -152,6 +153,7 @@ Ext.define('PVE.qemu.HDInputPanel', {
         values.diskformat = drive.format || 'raw';
         values.cache = drive.cache || '__default__';
         values.discard = drive.discard === 'on';
+        values.detect_zeroes = PVE.Parser.parseBoolean(drive.detect_zeroes, 1);
         values.ssd = PVE.Parser.parseBoolean(drive.ssd);
         values.iothread = PVE.Parser.parseBoolean(drive.iothread);
         values.readOnly = PVE.Parser.parseBoolean(drive.ro);
@@ -317,6 +319,12 @@ Ext.define('PVE.qemu.HDInputPanel', {
                 reference: 'discard',
                 name: 'discard',
             },
+            {
+                xtype: 'proxmoxcheckbox',
+                fieldLabel: gettext('Detect zeroes'),
+                reference: 'detect_zeroes',
+                name: 'detect_zeroes',
+            },
             {
                 xtype: 'proxmoxcheckbox',
                 name: 'iothread',
-- 
2.47.3

Re: [PATCH manager] ui: qemu: add detect zeroes disk option

[Fabian Grünbichler]

if I am not mistaken, this is a fix for
https://bugzilla.proxmox.com/show_bug.cgi?id=4503 ?

On June 8, 2026 10:36 am, Lukas Sichert wrote:
> When discard is enabled, qemu-server defaults to `detect-zeroes=unmap`.
> This can have a significant performance impact for zero writes on some
> setups, while users might still want to keep guest discard/TRIM support
> enabled.
> 
> Allow configuring the option independently so discard can stay enabled
> while zero detection is disabled. Persist the checkbox state explicitly,
> as the backend treats an absent value as the default-enabled behavior.
> 
> Signed-off-by: Lukas Sichert <l.sichert@proxmox.com>
> ---
>  www/manager6/qemu/HDEdit.js | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/www/manager6/qemu/HDEdit.js b/www/manager6/qemu/HDEdit.js
> index 1bb2bfda..d1d1b0fa 100644
> --- a/www/manager6/qemu/HDEdit.js
> +++ b/www/manager6/qemu/HDEdit.js
> @@ -96,6 +96,7 @@ Ext.define('PVE.qemu.HDInputPanel', {
>          PVE.Utils.propertyStringSet(me.drive, values.readOnly, 'ro', 'on');
>          PVE.Utils.propertyStringSet(me.drive, values.cache, 'cache');
>          PVE.Utils.propertyStringSet(me.drive, values.aio, 'aio');
> +        me.drive.detect_zeroes = values.detect_zeroes ? 1 : 0;

this should probably have a comment why this line is deviating from the
ones above (to not lose an explicit false value that clashes with the
implicit true default value of the backend).

>  
>          ['mbps_rd', 'mbps_wr', 'iops_rd', 'iops_wr'].forEach((name) => {
>              let burst_name = `${name}_max`;
> @@ -152,6 +153,7 @@ Ext.define('PVE.qemu.HDInputPanel', {
>          values.diskformat = drive.format || 'raw';
>          values.cache = drive.cache || '__default__';
>          values.discard = drive.discard === 'on';
> +        values.detect_zeroes = PVE.Parser.parseBoolean(drive.detect_zeroes, 1);
>          values.ssd = PVE.Parser.parseBoolean(drive.ssd);
>          values.iothread = PVE.Parser.parseBoolean(drive.iothread);
>          values.readOnly = PVE.Parser.parseBoolean(drive.ro);
> @@ -317,6 +319,12 @@ Ext.define('PVE.qemu.HDInputPanel', {
>                  reference: 'discard',
>                  name: 'discard',
>              },
> +            {
> +                xtype: 'proxmoxcheckbox',
> +                fieldLabel: gettext('Detect zeroes'),
> +                reference: 'detect_zeroes',
> +                name: 'detect_zeroes',
> +            },
>              {
>                  xtype: 'proxmoxcheckbox',
>                  name: 'iothread',
> -- 
> 2.47.3
> 
> 
> 
> 
> 
> 

Re: [PATCH manager] ui: qemu: add detect zeroes disk option

[Lukas Sichert]

On 2026-06-16 15:01, Fabian Grünbichler <f.gruenbichler@proxmox.com> wrote:

> if I am not mistaken, this is a fix for
> https://bugzilla.proxmox.com/show_bug.cgi?id=4503 ?

Yes, I have also corrected this in a v2 already [1], but I forgot to send a
superseded-by. Sorry for the confusion.

[1] https://lore.proxmox.com/all/20260610131827.11092-1-l.sichert@proxmox.com/

>
> On June 8, 2026 10:36 am, Lukas Sichert wrote:
>> When discard is enabled, qemu-server defaults to `detect-zeroes=unmap`.
>> This can have a significant performance impact for zero writes on some
>> setups, while users might still want to keep guest discard/TRIM support
>> enabled.
>> 
>> Allow configuring the option independently so discard can stay enabled
>> while zero detection is disabled. Persist the checkbox state explicitly,
>> as the backend treats an absent value as the default-enabled behavior.
>> 
>> Signed-off-by: Lukas Sichert <l.sichert@proxmox.com>
>> ---
>>  www/manager6/qemu/HDEdit.js | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>> 
>> diff --git a/www/manager6/qemu/HDEdit.js b/www/manager6/qemu/HDEdit.js
>> index 1bb2bfda..d1d1b0fa 100644
>> --- a/www/manager6/qemu/HDEdit.js
>> +++ b/www/manager6/qemu/HDEdit.js
>> @@ -96,6 +96,7 @@ Ext.define('PVE.qemu.HDInputPanel', {
>>          PVE.Utils.propertyStringSet(me.drive, values.readOnly, 'ro', 'on');
>>          PVE.Utils.propertyStringSet(me.drive, values.cache, 'cache');
>>          PVE.Utils.propertyStringSet(me.drive, values.aio, 'aio');
>> +        me.drive.detect_zeroes = values.detect_zeroes ? 1 : 0;
>
> this should probably have a comment why this line is deviating from the
> ones above (to not lose an explicit false value that clashes with the
> implicit true default value of the backend.

Thanks for looking over this. I will fix it in a v3.

>
>>  
>>          ['mbps_rd', 'mbps_wr', 'iops_rd', 'iops_wr'].forEach((name) => {
>>              let burst_name = `${name}_max`;
>> @@ -152,6 +153,7 @@ Ext.define('PVE.qemu.HDInputPanel', {
>>          values.diskformat = drive.format || 'raw';
>>          values.cache = drive.cache || '__default__';
>>          values.discard = drive.discard === 'on';
>> +        values.detect_zeroes = PVE.Parser.parseBoolean(drive.detect_zeroes, 1);
>>          values.ssd = PVE.Parser.parseBoolean(drive.ssd);
>>          values.iothread = PVE.Parser.parseBoolean(drive.iothread);
>>          values.readOnly = PVE.Parser.parseBoolean(drive.ro);
>> @@ -317,6 +319,12 @@ Ext.define('PVE.qemu.HDInputPanel', {
>>                  reference: 'discard',
>>                  name: 'discard',
>>              },
>> +            {
>> +                xtype: 'proxmoxcheckbox',
>> +                fieldLabel: gettext('Detect zeroes'),
>> +                reference: 'detect_zeroes',
>> +                name: 'detect_zeroes',
>> +            },
>>              {
>>                  xtype: 'proxmoxcheckbox',
>>                  name: 'iothread',
>> -- 
>> 2.47.3
>> 
>> 
>> 
>> 
>> 
>> 

superseded: [PATCH manager] ui: qemu: add detect zeroes disk option

[Lukas Sichert]

superseded-by v2:
https://lore.proxmox.com/all/20260610131827.11092-1-l.sichert@proxmox.com/