From 3dbe1daabf486120ee4611bfde1b81cf4504bcac Mon Sep 17 00:00:00 2001 From: Thomas Lamprecht Date: Wed, 6 Nov 2019 18:39:02 +0100 Subject: [PATCH] qm: add sub-headings to hard disk section and references Signed-off-by: Thomas Lamprecht --- qm.adoc | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/qm.adoc b/qm.adoc index 429cff6..2acf6b8 100644 --- a/qm.adoc +++ b/qm.adoc @@ -150,6 +150,9 @@ one want's to pass through PCIe hardware. Hard Disk ~~~~~~~~~ +[[qm_hard_disk_bus]] +Bus/Controller +^^^^^^^^^^^^^^ Qemu can emulate a number of storage controllers: * the *IDE* controller, has a design which goes back to the 1984 PC/AT disk @@ -182,6 +185,10 @@ is an older type of paravirtualized controller. It has been superseded by the VirtIO SCSI Controller, in terms of features. [thumbnail="screenshot/gui-create-vm-hard-disk.png"] + +[[qm_hard_disk_formats]] +Image Format +^^^^^^^^^^^^ On each controller you attach a number of emulated hard disks, which are backed by a file or a block device residing in the configured storage. The choice of a storage type will determine the format of the hard disk image. Storages which @@ -200,6 +207,9 @@ either the *raw disk image format* or the *QEMU image format*. * the *VMware image format* only makes sense if you intend to import/export the disk image to other hypervisors. +[[qm_hard_disk_cache]] +Cache Mode +^^^^^^^^^^ Setting the *Cache* mode of the hard drive will impact how the host system will notify the guest systems of block write completions. The *No cache* default means that the guest system will be notified that a write is complete when each @@ -215,6 +225,9 @@ As of {pve} 5.0, replication requires the disk images to be on a storage of type `zfspool`, so adding a disk image to other storages when the VM has replication configured requires to skip replication for this disk image. +[[qm_hard_disk_discard]] +Trim/Discard +^^^^^^^^^^^^ If your storage supports _thin provisioning_ (see the storage chapter in the {pve} guide), you can activate the *Discard* option on a drive. With *Discard* set and a _TRIM_-enabled guest OS footnote:[TRIM, UNMAP, and discard @@ -232,7 +245,10 @@ that drive. There is no requirement that the underlying storage actually be backed by SSDs; this feature can be used with physical media of any type. Note that *SSD emulation* is not supported on *VirtIO Block* drives. -.IO Thread + +[[qm_hard_disk_iothread]] +IO Thread +^^^^^^^^^ The option *IO Thread* can only be used when using a disk with the *VirtIO* controller, or with the *SCSI* controller, when the emulated controller type is *VirtIO SCSI single*. -- 2.39.2