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Re: [qemu-web PATCH v3] Add virtio-blk and virtio-scsi configuration pos

From: Thomas Huth
Subject: Re: [qemu-web PATCH v3] Add virtio-blk and virtio-scsi configuration post
Date: Thu, 21 Jan 2021 12:47:08 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0

On 19/01/2021 15.15, Stefan Hajnoczi wrote:
The second post in the storage series covers virtio-blk and virtio-scsi.
It compares the two and offers recommendations that users and tools
using QEMU can use as a starting point. Graphs are included comparing
the performance of various options.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
  * Mention guest drivers for other operation systems [Thomas]
  * Reorder virtio-blk/virtio-scsi key points [Thomas]
  * Mention that virtio-blk is limited to disk emulation and doesn't
    handle CD-ROM drivers, for example [Thomas]
  * Mention default storage controllers for non-x86 [danpb]
  * Remove statement about read-only ISO virtio-blk devices, both Rich
    Jones and Daniel Berrange commented about this at different times so
    I decided to drop it completely [danpb]
  * Clarify PCI slot limits and multi-function discussion for virtio-blk
  * Mention multiple virtio-scsi devices for NUMA tuning and that
    emulated LUNs can be HDDs or CD-ROMs [danpb]
  ...021-01-19-virtio-blk-scsi-configuration.md | 117 ++++++++++++++++++
  screenshots/2020-09-15-scsi-devices.svg       |   1 +
  screenshots/2020-09-15-virtio-blk-vs-scsi.svg |   1 +
  3 files changed, 119 insertions(+)
  create mode 100644 _posts/2021-01-19-virtio-blk-scsi-configuration.md
  create mode 100644 screenshots/2020-09-15-scsi-devices.svg
  create mode 100644 screenshots/2020-09-15-virtio-blk-vs-scsi.svg

diff --git a/_posts/2021-01-19-virtio-blk-scsi-configuration.md 
new file mode 100644
index 0000000..a9c7a35
--- /dev/null
+++ b/_posts/2021-01-19-virtio-blk-scsi-configuration.md
@@ -0,0 +1,117 @@
+Virtual machines that require access to many disks can hit limits based on
+availability of PCI slots, which are under contention with other devices
+exposed to the guest, such as NICs. For example a typical i440fx machine type
+default configuration allows for about 28 disks. It is possible to use
+multi-function devices to pack multiple virtio-blk devies into a single PCI


I've replaced "devies" with "devices" and pushed it to the repo now.


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