Hi, if "MAX AVAIL" displays the wrong data, the bug is just made more visible through the dashboard, as the calculation is correct. To get the right percentage you have to divide the used space through the total, and the total can only consist of two states used and not used space, so both states will be added together to get the total. Or in short: used / (avail + used) Just looked into the C++ code - Max avail will be calculated the following way: avail_res = avail / raw_used_rate ( https://github.com/ceph/ceph/blob/nautilus/src/mon/PGMap.cc#L905) raw_used_rate *= (sum.num_object_copies - sum.num_objects_degraded) / sum.num_object_copies (https://github.com/ceph/ceph/blob/nautilus/src/mon/PGMap.cc#L892) Am Dienstag, den 17.12.2019, 07:07 +0100 schrieb ceph@elchaka.de:
I have observed this in the ceph nautilus dashboard too - and Think it is a Display Bug... but sometimes it Shows tue right values
Which nautilus u use?
Am 10. Dezember 2019 14:31:05 MEZ schrieb "David Majchrzak, ODERLAND Webbhotell AB" <david@oderland.se>:
Hi!
While browsing /#/pool in nautilus ceph dashboard I noticed it said 93% used on the single pool we have (3x replica).
ceph df detal however shows 81% used on the pool and 67% raw useage.
# ceph df detail RAW STORAGE: CLASS SIZE AVAIL USED RAW USED %RAW USED ssd 478 TiB 153 TiB 324 TiB 325 TiB 67.96 TOTAL 478 TiB 153 TiB 324 TiB 325 TiB 67.96
POOLS: POOL ID STORED OBJECTS USED %USED
MAX AVAIL QUOTA OBJECTS QUOTA BYTES DIRTY USED COMPR UNDER COMPR echo 3 108 TiB 29.49M 324 TiB 81.61 24 TiB N/A N/A 29.49M 0 B 0 B
I manually calculated the used percentage to get "avail" in your case it seems to be 73 TiB. That means the the total space available for your pool would be 397 TiB. I'm not sure why that is, but it's what the math behind those calculations say. (Found a thread regarding that on the new mailing list (ceph- users@ceph.io) -> https://lists.ceph.io/hyperkitty/list/ceph-users@ceph.io/thread/NH2LMMX5KVRW... ) 0.8161 = used (324) / total => total = 397 Than I looked at the remaining calculations: raw_used_rate *= (sum.num_object_copies - sum.num_objects_degraded) / sum.num_object_copies and avail_res = avail / raw_used_rate First I looked up the init value for "raw_used_rate" for replicated pools. It's their size so we can put in 3 here and for "avail_res" is 24. So I first calculated the final "raw_used_rate" which is 3.042. That means that you have around 4.2% degraded pg's in your pool.
I know we're looking at the most full OSD (210PGs, 79% used, 1.17 VAR) and count max avail from that. But where's the 93% full from in dashboard?
As said above the calculation is right but the data is wrong... As it uses the real data that can be put in the selected pool, but it uses everywhere else sizes that consider all pool replicas. I created an issue to fix this https://tracker.ceph.com/issues/43384
My guess is that is comes from calculating:
1 - Max Avail / (Used + Max avail) = 0.93
Kind Regards,
David Majchrzak
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Hope I could clarify some things and thanks for your feedback :) BTW this problem currently still exists as there wasn't any change to these mentioned lines after the nautilus release. Stephan