Bug 510486
Summary: | mdadm should prefere multipath devices before raw devices | ||
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Product: | [Fedora] Fedora | Reporter: | Tomasz Torcz <tomek> |
Component: | mdadm | Assignee: | Doug Ledford <dledford> |
Status: | CLOSED INSUFFICIENT_DATA | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
Severity: | medium | Docs Contact: | |
Priority: | low | ||
Version: | 11 | CC: | dledford, notting |
Target Milestone: | --- | ||
Target Release: | --- | ||
Hardware: | All | ||
OS: | Linux | ||
Whiteboard: | |||
Fixed In Version: | Doc Type: | Bug Fix | |
Doc Text: | Story Points: | --- | |
Clone Of: | Environment: | ||
Last Closed: | 2010-02-25 12:55:30 UTC | Type: | --- |
Regression: | --- | Mount Type: | --- |
Documentation: | --- | CRM: | |
Verified Versions: | Category: | --- | |
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
Cloudforms Team: | --- | Target Upstream Version: | |
Embargoed: |
Description
Tomasz Torcz
2009-07-09 13:11:14 UTC
This is not likely something that can be solved in mdadm (at least not entirely). There are two problems: 1) mdadm device assembly is done before multipath device assembly in rc.sysinit. This means that the md assembly will always grab one of the multipath devices before devmapper can get it. 2) mdadm is assembling devices incrementally these days, and that means it isn't looking at all available devices and then deciding what to assemble, it's only looking at one specific device, the one udev tells it to look at, and then deciding whether or not to assemble. As such, it's not possible to make mdadm do "when given the choice between sda, sde, or dm-1, choose dm-1 first". So, mainly due to #2 above, I think the only way you are going to be able to use dm-multipath and md raid over dm-multipath is to edit your /etc/mdadm.conf file and change the DEVICE option from partitions to /dev/dm*, at which point mdadm should refuse to create a raid array from the /dev/sd?? devices even when udev calls mdadm's incremental assembly on them, and should instead only perform the assembly when the multipath devices come on line. I'm adding Bill Nottingham to the Cc list on this so he can confirm my suspicion, but if I'm right and the workaround fixes your issue, then that's likely the best that can be done in mdadm at least, it would need anaconda changes so that anaconda knew to modify mdadm.conf to ignore multipath constituent devices on install to make this happen automatically. Please let us know if the workaround does in fact work. I'm soryy, I don't have that hardware anymore, so I cannot test. Your workaround seems plausible. |