Hi there. I have configured a POOL with a 8+2 erasure code. My target by space usage and OSD configuration, would be 128 PG, but since each configure PG will be using 10 actual "PGs", I have created the pool with only 8 PG (80 real PG). Since I can increase PGs but not decreasing it, this decision seems sensible. Some questions: 1. Documentation insists everywhere that the PG could should be a power of two. Would be nice to know the consequences of not following this recommendation. Would be nice to know too if being "close" to a power of two is better than be far away and if it is better to be close but below or close but a little bit more. If ideal value is 128 but I only can be 120 or 130, what should I choose?. 120 or 130?. Why? 2. As I understand, the PG count that should be "power of two" is "8", in this case (real 80 PG underneath). Good. In this case, the next step would be 16 (160 real PG). I would rather prefer to increase it to 12 or 13 (120/130 real PGs). Would it be reasonable?. What are the consequences of increasing PG to 12 or 13 instead of choosing 16 (the next power of two). 3. Is there any negative effect for CRUSH of using erasure code 8+2 instead of 6+2 or 14+2 (power of two)?. I have 25 OSDs, so requiring 16 for a single operation seems a bad idea, even more when my OSD capacities are very spread (from 150 GB to 1TB) and filling a small OSD would block writes in the entire pool. 4. Since I have created a erasure coded pool with 8 PG, I am getting warnings of "x pools have many more objects per pg than average". The data I am copying is coming from a legacy pool with PG=512. New pool PG is 8. That is creating ~30.000 objects per PG, far above average (616 objects). What can I do?. Moving to 16 or 32 PGs is not going to improve the situation, but will consume PGs (32*10). Advice?. 5. I understand the advice of having <300 PGs per OSD because memory usage, but I am wondering about the impact of the number of objects in each PG. I wonder if memory and resource wise, having 100 PG with 10.000 objects each is far more demanding than 1000 PGs with 50 objects each. Since I have PGs with 300 objects and PGs with 30.000 objects, I wonder about the memory impact of each. What is the actual memory hungry factor in a OSD, PGs or objects per PG?. Thanks for your time and knowledge :). -- Jesús Cea Avión _/_/ _/_/_/ _/_/_/ jcea@xxxxxxx - http://www.jcea.es/ _/_/ _/_/ _/_/ _/_/ _/_/ Twitter: @jcea _/_/ _/_/ _/_/_/_/_/ jabber / xmpp:jcea@xxxxxxxxxx _/_/ _/_/ _/_/ _/_/ _/_/ "Things are not so easy" _/_/ _/_/ _/_/ _/_/ _/_/ _/_/ "My name is Dump, Core Dump" _/_/_/ _/_/_/ _/_/ _/_/ "El amor es poner tu felicidad en la felicidad de otro" - Leibniz
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