On Tue, Jun 06, 2017 at 01:57:27PM +1000, NeilBrown wrote:
quoted
The first bitmap line shows 3 pages totallying 12KB, so each page
contains 4KB, or 2048 chunks per page.
Did the above say that I had 6144 chunks that needed to be synced?
No. It said that of the 44 pages of space that might be needed to store
16-bit counters that each represent 1 bitmap-chunk, only 3 of those
pages would contain non-zero counters, so only 3 had been allocated.
There could be as few as 3 chunks that need to be recovered, or there
could be as many a 3*2048 chunks, or any number in between.
Ah, I see. I wasn't clear about that part, thanks.
Had you run "mdadm --examine-bitmap /dev/sdk1" before the re-add, it
would have told you how many bits were set at that time.
Noted for next time, thanks.
quoted
The part I'm not too clear about is 44 pages of intent isn't enough to
cover all my data.
44 pages means 90112 16 bit counters, one for each 64M on each device.
90112 * 64M = 5632 GiB or 5905GB.
That is the size of each device.
Ah, so it's not based on the 512k chunk size, I see.
One bit in the bitmap (one counter in the internal bitmap) corresponds
to "a set of data the might be out of sync" which, in your case, is a
64MB wide stripe across all devices.
I got that part now, just now where the 64MB came from, or how I ended
up with 44 pages of intent maps if it's not based on my chunk size.
Thanks,
Marc
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Microsoft is to operating systems ....
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Home page: http://marc.merlins.org/ | PGP 1024R/763BE901