Wrong read balance when a drive is write-mostly
Bug #1446786 reported by
Dmitry Maslennikov
This bug affects 1 person
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Expired
|
Medium
|
Unassigned | ||
Precise |
Expired
|
Medium
|
Unassigned |
Bug Description
This bug related to `mdadm` `--write-mostly` option. When we create SSD for read operation, but want to use HDD to mirror SSD content we can create RAID-1 with SSD and 'write-mostly' HDD disk.
In Ubuntu kernel there is a bug, which lead to havy read from both SSD and HDD drives. More over if we add HDD as regular disk and SSD as a 'write-mostly' replica most read operations will go to SSD drive (which is clear from sources and we have prove it in our setup).
In upstream kernel sources this was already fixed:
https:/
Could you backport this functionality? - This patch looks safe to apply as is.
Changed in linux (Ubuntu): | |
importance: | Undecided → Medium |
tags: | added: precise |
Changed in linux (Ubuntu): | |
status: | Incomplete → Triaged |
tags: | added: bot-stop-nagging kernel-da-key |
Changed in linux (Ubuntu): | |
status: | In Progress → Incomplete |
Changed in linux (Ubuntu Precise): | |
status: | In Progress → Incomplete |
Changed in linux (Ubuntu): | |
assignee: | Joseph Salisbury (jsalisbury) → nobody |
Changed in linux (Ubuntu Precise): | |
assignee: | Joseph Salisbury (jsalisbury) → nobody |
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Forget to add that we use Ubuntu 12.04