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From "Wido den Hollander (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CLOUDSTACK-8104) Add TRIM/Discard support to Qemu
Date Mon, 22 Dec 2014 15:22:13 GMT

     [ https://issues.apache.org/jira/browse/CLOUDSTACK-8104?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Wido den Hollander updated CLOUDSTACK-8104:
-------------------------------------------
    Description: 
Thinly provisioned volumes on storage devices continue to grow because the storage device
has no idea of which blocks are in use.

For SSDs the TRIM/Discard feature was invented to give free/unused blocks back to the flash
device, but this can also be used for Qemu.

Ceph's RBD for example supports trimming so that volumes can shrink again when blocks are
no longer in use.

This is supported since Qemu 1.5, but since 1.6 it also works for QCOW2 images.

It however requires the new virtio-scsi to work optimal, so it requires some changes.

For more information see:
* http://wiki.qemu.org/ChangeLog/1.5#Block_devices
* http://wiki.qemu.org/ChangeLog/1.6#Block_devices
* http://ceph.com/docs/master/rbd/qemu-rbd/#enabling-discard-trim
* http://wiki.qemu.org/Features/VirtioSCSI

  was:
Thinly provisioned volumes on storage devices continue to grow because the storage device
has no idea of which blocks are in use.

For SSDs the TRIM/Discard feature was invented to give free/unused blocks back to the flash
device, but this can also be used for Qemu.

Ceph's RBD for example supports trimming so that volumes can shrink again when blocks are
no longer in use.

This is supported since Qemu 1.5, but since 1.6 it also works for QCOW2 images.

It however requires the new virtio-scsi to work optimal, so it requires some changes.

For more information see:
* http://wiki.qemu.org/ChangeLog/1.5#Block_devices
* http://wiki.qemu.org/ChangeLog/1.6#Block_devices
* http://ceph.com/docs/master/rbd/qemu-rbd/#enabling-discard-trim


> Add TRIM/Discard support to Qemu
> --------------------------------
>
>                 Key: CLOUDSTACK-8104
>                 URL: https://issues.apache.org/jira/browse/CLOUDSTACK-8104
>             Project: CloudStack
>          Issue Type: New Feature
>      Security Level: Public(Anyone can view this level - this is the default.) 
>          Components: KVM
>            Reporter: Wido den Hollander
>            Assignee: Wido den Hollander
>            Priority: Minor
>
> Thinly provisioned volumes on storage devices continue to grow because the storage device
has no idea of which blocks are in use.
> For SSDs the TRIM/Discard feature was invented to give free/unused blocks back to the
flash device, but this can also be used for Qemu.
> Ceph's RBD for example supports trimming so that volumes can shrink again when blocks
are no longer in use.
> This is supported since Qemu 1.5, but since 1.6 it also works for QCOW2 images.
> It however requires the new virtio-scsi to work optimal, so it requires some changes.
> For more information see:
> * http://wiki.qemu.org/ChangeLog/1.5#Block_devices
> * http://wiki.qemu.org/ChangeLog/1.6#Block_devices
> * http://ceph.com/docs/master/rbd/qemu-rbd/#enabling-discard-trim
> * http://wiki.qemu.org/Features/VirtioSCSI



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