在 2025/9/15 8:33, Xiao Ni 写道:
Hi Nan
On Thu, Sep 11, 2025 at 3:41 PM <linan666@xxxxxxxxxxxxxxx> wrote:
From: Li Nan <linan122@xxxxxxxxxx>
Previously, raid array used the maximum logical_block_size (LBS) of
all member disks. Adding a larger LBS during disk at runtime could
unexpectedly increase RAID's LBS, risking corruption of existing
partitions.
Could you describe more about the problem? It's better to give some
test steps that can be used to reproduce this problem.
Thanks for your review. I will add reproducer in the next version.
Simply restricting larger-LBS disks is inflexible. In some scenarios,
only disks with 512 LBS are available currently, but later, disks with
4k LBS may be added to the array.
Making LBS configurable is the best way to solve this scenario.
After this patch, the raid will:
- stores LBS in disk metadata.
- add a read-write sysfs 'mdX/logical_block_size'.
Future mdadm should support setting LBS via metadata field during RAID
creation and the new sysfs. Though the kernel allows runtime LBS changes,
users should avoid modifying it after creating partitions or filesystems
to prevent compatibility issues.
Because it only allows setting when creating an array. Can this be
done automatically in kernel space?
Best Regards
Xiao
The kernel defaults LBS to the max among all rdevs. When creating RAID
with mdadm, if mdadm doesn't set LBS explicitly, how does the kernel
learn the intended value?
Gunaghao previously submitted a patch related to mdadm:
https://lore.kernel.org/all/3a9fa346-1041-400d-b954-2119c1ea001c@xxxxxxxxxx/
--
Thanks,
Nan
