* Events Counter - How it increments @ 2020-11-10 14:24 Jorge Fábregas 2020-11-17 15:50 ` Jorge Fábregas 2020-11-18 16:45 ` heming.zhao 0 siblings, 2 replies; 6+ messages in thread From: Jorge Fábregas @ 2020-11-10 14:24 UTC (permalink / raw) To: linux-raid Hi everyone, I'm new to Linux RAID. I've searched for a clear explanation on this but couldn't find it. How does the "Events" counter (as shown with mdadm --examine) gets incremented? On what sort of events? I was initially confused about the "Events" (thinking on the different events as reported by mdadm --monitor) but I see this is another thing. I've seen explanations about it incrementing after performing writes but I've done some test writes and I don't see the counters changing at all on my RAID1 arrays. I've also seen explanations that it increments whenever there are changes to the superblock? Thank you. -- Jorge ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Events Counter - How it increments 2020-11-10 14:24 Events Counter - How it increments Jorge Fábregas @ 2020-11-17 15:50 ` Jorge Fábregas 2020-11-18 16:45 ` heming.zhao 1 sibling, 0 replies; 6+ messages in thread From: Jorge Fábregas @ 2020-11-17 15:50 UTC (permalink / raw) To: linux-raid On 11/10/20 10:24 AM, Jorge Fábregas wrote: > How does the "Events" counter (as shown with mdadm --examine) gets > incremented? On what sort of events? Anyone? :) Thank you. -- Jorge ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Events Counter - How it increments 2020-11-10 14:24 Events Counter - How it increments Jorge Fábregas 2020-11-17 15:50 ` Jorge Fábregas @ 2020-11-18 16:45 ` heming.zhao 2020-11-19 2:21 ` Jorge Fábregas 1 sibling, 1 reply; 6+ messages in thread From: heming.zhao @ 2020-11-18 16:45 UTC (permalink / raw) To: Jorge Fábregas, linux-raid On 11/10/20 10:24 PM, Jorge Fábregas wrote: > Hi everyone, > > I'm new to Linux RAID. I've searched for a clear explanation on this but > couldn't find it. > > How does the "Events" counter (as shown with mdadm --examine) gets > incremented? On what sort of events? > > I was initially confused about the "Events" (thinking on the different > events as reported by mdadm --monitor) but I see this is another thing. > I've seen explanations about it incrementing after performing writes but > I've done some test writes and I don't see the counters changing at all > on my RAID1 arrays. I've also seen explanations that it increments > whenever there are changes to the superblock? > > Thank you. > The events is related with (struct mddev) mddev->events. you can search it in kernel source code. and the 'events' is also recorded in md metadata area, with struct: ``` struct mdp_superblock_1 { ... ... __le64 events; /* incremented when superblock updated */ ... ... }; ``` ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Events Counter - How it increments 2020-11-18 16:45 ` heming.zhao @ 2020-11-19 2:21 ` Jorge Fábregas 2020-11-19 11:27 ` heming.zhao 0 siblings, 1 reply; 6+ messages in thread From: Jorge Fábregas @ 2020-11-19 2:21 UTC (permalink / raw) To: linux-raid On 11/18/20 12:45 PM, heming.zhao@suse.com 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. 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? Thanks. -- Jorge ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Events Counter - How it increments 2020-11-19 2:21 ` Jorge Fábregas @ 2020-11-19 11:27 ` heming.zhao 2020-11-19 11:46 ` Jorge Fábregas 0 siblings, 1 reply; 6+ messages in thread From: heming.zhao @ 2020-11-19 11:27 UTC (permalink / raw) To: Jorge Fábregas, linux-raid Hello, On 11/19/20 10:21 AM, Jorge Fábregas wrote: > On 11/18/20 12:45 PM, heming.zhao@suse.com 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. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Events Counter - How it increments 2020-11-19 11:27 ` heming.zhao @ 2020-11-19 11:46 ` Jorge Fábregas 0 siblings, 0 replies; 6+ messages in thread From: Jorge Fábregas @ 2020-11-19 11:46 UTC (permalink / raw) To: linux-raid On 11/19/20 7:27 AM, heming.zhao@suse.com wrote: > 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 Thanks Heming for the breakdown. That was helpful. -- - Jorge ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-11-19 11:46 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-11-10 14:24 Events Counter - How it increments Jorge Fábregas 2020-11-17 15:50 ` Jorge Fábregas 2020-11-18 16:45 ` heming.zhao 2020-11-19 2:21 ` Jorge Fábregas 2020-11-19 11:27 ` heming.zhao 2020-11-19 11:46 ` Jorge Fábregas
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