[Including ceph-users alias] 2015-08-03 16:01 GMT+08:00 乔建峰 <[email protected]>:
> Hi Cephers, > > Currently, I'm experiencing an issue which suffers me a lot, so I'm > writing to ask for your comments/help/suggestions. More details are > provided bellow. > > Issue: > I set up a cluster having 24 OSDs and created one pool with 1024 placement > groups on it for a small startup company. The number 1024 was calculated > per the equation (OSDs * 100)/pool size. The cluster have been running > quite well for a long time. But recently, our monitoring system always > complains that some disks' usage exceed 85%. I log into the system and find > out that some disks' usage are really very high, but some are not(less than > 60%). Each time when the issue happens, I have to manually re-balance the > distribution. This is a short-term solution, I'm not willing to do it all > the time. > > Two long-term solutions come in my mind, > 1) Ask the customers to expand their clusters by adding more OSDs. But I > think they will ask me to explain the reason of the imbalance data > distribution. We've already done some analysis on the environment, we > learned that the most imbalance part in the CRUSH is the mapping between > object and pg. The biggest pg has 613 objects, while the smallest pg only > has 226 objects. > > 2) Increase the number of placement groups. It can be of great help for > statistically uniform data distribution, but it can also incur significant > data movement as PGs are effective being split. I just cannot do it in our > customers' environment before we 100% understand the consequence. So anyone > did this under a production environment? How much does this operation > affect the performance of Clients? > > Any comments/help/suggestions will be highly appreciated. > > -- > Best Regards > Jevon > -- Best Regards Jevon
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