[libvirt-users] Make discard='unmap' the default?
Is it possible to make discard='unmap' the default for virtio-scsi disks? (Related, is it possible to make virtio-scsi the default disk type, rather than virtio-blk?) Thanks! -- ======================================================================== Ian Pilcher arequipeno@gmail.com -------- "I grew up before Mark Zuckerberg invented friendship" -------- ========================================================================
On Thu, May 31, 2018 at 02:34:15PM -0500, Ian Pilcher wrote:
Is it possible to make discard='unmap' the default for virtio-scsi disks? (Related, is it possible to make virtio-scsi the default disk type, rather than virtio-blk?)
This is really a question for whatever management tool you're using with libvirt, since it is essentially defining an opinionated usage policy. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On 06/01/2018 05:19 AM, Daniel P. Berrangé wrote:
On Thu, May 31, 2018 at 02:34:15PM -0500, Ian Pilcher wrote:
Is it possible to make discard='unmap' the default for virtio-scsi disks? (Related, is it possible to make virtio-scsi the default disk type, rather than virtio-blk?)
This is really a question for whatever management tool you're using with libvirt, since it is essentially defining an opinionated usage policy.
I'm using virt-manager. I was under the impression that it gets its "hypervisor default" device types from libvirt. -- ======================================================================== Ian Pilcher arequipeno@gmail.com -------- "I grew up before Mark Zuckerberg invented friendship" -------- ========================================================================
On Fri, Jun 01, 2018 at 07:54:32AM -0500, Ian Pilcher wrote:
On 06/01/2018 05:19 AM, Daniel P. Berrangé wrote:
On Thu, May 31, 2018 at 02:34:15PM -0500, Ian Pilcher wrote:
Is it possible to make discard='unmap' the default for virtio-scsi disks? (Related, is it possible to make virtio-scsi the default disk type, rather than virtio-blk?)
This is really a question for whatever management tool you're using with libvirt, since it is essentially defining an opinionated usage policy.
I'm using virt-manager. I was under the impression that it gets its "hypervisor default" device types from libvirt.
Yes, it inherits some defaults to libvirt and/or QEMU. If those are not suitable for some reason, then virt-manager needs to override it. The decision about whether to enable discard or not is a policy decision that doesn't have a single perfect answer. So changing it in libvirt might make it better for you, but worse for someone else. Libvirt does not want to get into such debates, so leaves such decisions for the app above to make, where there may well be more global context/knowledge allowing a better choice. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On 06/01/2018 08:14 AM, Daniel P. Berrangé wrote:
Yes, it inherits some defaults to libvirt and/or QEMU. If those are not suitable for some reason, then virt-manager needs to override it. The decision about whether to enable discard or not is a policy decision that doesn't have a single perfect answer. So changing it in libvirt might make it better for you, but worse for someone else. Libvirt does not want to get into such debates, so leaves such decisions for the app above to make, where there may well be more global context/knowledge allowing a better choice.
To be clear, I'm not suggesting that the "default defaults" be changed, I would just like to change the default on my personal system. It sounds like you're saying that libvirt expects virt-manager to override these settings (if it wants to), but virt-manager doesn't provide any way to do so, since it just uses the defaults from libvirt/ QEMU. -- ======================================================================== Ian Pilcher arequipeno@gmail.com -------- "I grew up before Mark Zuckerberg invented friendship" -------- ========================================================================
On Fri, Jun 01, 2018 at 08:37:30AM -0500, Ian Pilcher wrote:
On 06/01/2018 08:14 AM, Daniel P. Berrangé wrote:
Yes, it inherits some defaults to libvirt and/or QEMU. If those are not suitable for some reason, then virt-manager needs to override it. The decision about whether to enable discard or not is a policy decision that doesn't have a single perfect answer. So changing it in libvirt might make it better for you, but worse for someone else. Libvirt does not want to get into such debates, so leaves such decisions for the app above to make, where there may well be more global context/knowledge allowing a better choice.
To be clear, I'm not suggesting that the "default defaults" be changed, I would just like to change the default on my personal system.
It sounds like you're saying that libvirt expects virt-manager to override these settings (if it wants to), but virt-manager doesn't provide any way to do so, since it just uses the defaults from libvirt/ QEMU.
Yes, exactly. IOW, perhaps file an RFE against virt-manager Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On Fri, Jun 01, 2018 at 02:47:38PM +0100, Daniel P. Berrangé wrote:
On Fri, Jun 01, 2018 at 08:37:30AM -0500, Ian Pilcher wrote:
On 06/01/2018 08:14 AM, Daniel P. Berrangé wrote:
Yes, it inherits some defaults to libvirt and/or QEMU. If those are not suitable for some reason, then virt-manager needs to override it. The decision about whether to enable discard or not is a policy decision that doesn't have a single perfect answer. So changing it in libvirt might make it better for you, but worse for someone else. Libvirt does not want to get into such debates, so leaves such decisions for the app above to make, where there may well be more global context/knowledge allowing a better choice.
To be clear, I'm not suggesting that the "default defaults" be changed, I would just like to change the default on my personal system.
It sounds like you're saying that libvirt expects virt-manager to override these settings (if it wants to), but virt-manager doesn't provide any way to do so, since it just uses the defaults from libvirt/ QEMU.
Yes, exactly. IOW, perhaps file an RFE against virt-manager
There is a way how to set few defaults (Edit->Preferences->New VM) but this one is not there. Creating RFE sounds reasonable. Pavel
participants (3)
-
Daniel P. Berrangé -
Ian Pilcher -
Pavel Hrdina