Hello,
On 11/19/20 10:21 AM, Jorge Fábregas wrote:
> On 11/18/20 12:45 PM, heming.zhao@xxxxxxxx wrote:
>> The events is related with (struct mddev) mddev->events.
>> you can search it in kernel source code.
>
> Thank you Heming. I was expecting more of a general view since I'm a
> new user. Sorry I wasn't clear.
>
very general overview: if array status/superblock is changed, event will increase.
> What sort of events cause the Event counter to increase? If it's mainly
> whenever the superblock is updated then my question is: What sort of
> events cause the superblock to be updated? I can imagine detection of
> failed disk, read errors, array checks, commands by user/admin,
> assembly-reassembly etc? If an array operates fine for months - without
> user intervention, will the Event counter increase at all?
>
the status/event is the content of struct mdp_superblock_1:
__le64 ctime; /* lo 40 bits are seconds, top 24 are microseconds or 0*/
__le32 level; /* -4 (multipath), -1 (linear), 0,1,4,5 */
__le32 layout; /* only for raid5 and raid10 currently */
__le64 size; /* used size of component devices, in 512byte sectors */
__le32 chunksize; /* in 512byte sectors */
__le32 raid_disks;
... ...
__le64 reshape_position; /* next address in array-space for reshape */
__le32 delta_disks; /* change in number of raid_disks */
__le32 new_layout; /* new layout */
... ...
__le32 dev_number; /* permanent identifier of this device - not role in raid */
... ...
__le16 dev_roles[0]; /* role in array, or 0xffff for a spare, or 0xfffe for faulty */
I am not very familiar with md, and can't enumerate all the cases. For your writing:
failed disk - dev_roles[X]
read errors - may change: dev_roles[X], recovery_offset
array checks - normally won't change, except disk fail is detected
commands by user - depend on special cmd
If an array operates fine for months - without user intervention - won't change
at last, please read the code.
Thanks.
