| Summary: | [Doc] Domain OS can't boot up from specified disk when existing more than 8 multifunction "virtio-blk-pci" disks in that domain. | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 7 | Reporter: | Tahlia Richardson <trichard> |
| Component: | doc-Virtualization_Deployment_and_Administration_Guide | Assignee: | Charlie <cboyle> |
| Status: | CLOSED CURRENTRELEASE | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 7.0 | CC: | ajia, dyuan, flang, hhuang, honzhang, jiahu, juzhang, knoel, kraxel, lersek, lnovich, mzhan, pbonzini, rlandman, trichard, virt-bugs, virt-docs, virt-maint, xuhan, yruseva |
| Target Milestone: | rc | Keywords: | Documentation, Triaged |
| Target Release: | --- | ||
| Hardware: | x86_64 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| 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.
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Story Points: | --- |
| Clone Of: | 1034072 | Environment: | |
| Last Closed: | 2015-03-06 03:27:07 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Bug Depends On: | 1034072 | ||
| Bug Blocks: | |||
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Comment 4
Gerd Hoffmann
2014-03-31 10:36:05 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. looks good to me. Thanks for reviewing, Gerd. 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. |