Bug 1040714 - [Doc] Domain OS can't boot up from specified disk when existing more than 8 multifunction "virtio-blk-pci" disks in that domain.
Summary: [Doc] Domain OS can't boot up from specified disk when existing more than 8 m...
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: doc-Virtualization_Deployment_and_Administration_Guide
Version: 7.0
Hardware: x86_64
OS: Linux
medium
medium
Target Milestone: rc
: ---
Assignee: Charlie
QA Contact:
URL:
Whiteboard:
Depends On: 1034072
Blocks:
TreeView+ depends on / blocked
 
Reported: 2013-12-12 00:29 UTC by Tahlia Richardson
Modified: 2019-03-06 01:23 UTC (History)
20 users (show)

Fixed In Version:
Doc Type: Known Issue
Doc Text:
The SeaBIOS application runs in real mode for compatibility with BIOS interfaces. This limits the amount of memory available. As a consequpci holeence, SeaBIOS is only able to handle a limited number of disks. Currently, the supported number of disks is: virtio-scsi — 64 virtio-blk — 4 ahci/sata — 24 (4 controllers with all 6 ports connected) usb-storage — 4 As a workaround for this problem, when attaching a large number of disks to your virtual machine, make sure that your system disk has a small pci slot number, so SeaBIOS sees it first when scanning the pci bus. It is also recommended to use the virtio-scsi device instead of virtio-blk as the per-disk memory overhead is smaller.
Clone Of: 1034072
Environment:
Last Closed: 2015-03-06 03:27:07 UTC
Target Upstream Version:

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Comment 4 Gerd Hoffmann 2014-03-31 10:36:05 UTC 
Updated doc text field.

Extra note: the real solution for this problem is to use UEFI instead, so we are no longer constrained by BIOS interfaces defined decades ago.

We don't support UEFI (yet), so I think we should wait with write that into the docs until UEFI is supported or at least in tech-preview.  Laszlo, agree?
Comment 5 Laszlo Ersek 2014-03-31 10:50:07 UTC 
(In reply to Gerd Hoffmann from comment #4)
> Updated doc text field.
> 
> Extra note: the real solution for this problem is to use UEFI instead, so we
> are no longer constrained by BIOS interfaces defined decades ago.

Seems reasonable.

> We don't support UEFI (yet), so I think we should wait with write that into
> the docs until UEFI is supported or at least in tech-preview.  Laszlo, agree?

Yes, I agree. We shouldn't promise in 7.0 that we'll promise in 7.1 that we'll support OVMF for real starting with 7.2.

I also fixed a misplaced comma in the Doc Text.
Comment 13 Gerd Hoffmann 2015-02-23 14:23:24 UTC 
looks good to me.
Comment 14 Dayle Parker 2015-03-06 03:20:18 UTC 
Thanks for reviewing, Gerd.
Comment 15 Dayle Parker 2015-03-06 03:27:07 UTC 
This change is now available in the released RHEL7.1 documentation at https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/.

Closing as CURRENTRELEASE.
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