Aleksey Gutikov wrote a detailed response to a similar question last year, maybe this will help? http://lists.ceph.com/pipermail/ceph-users-ceph.com/2019-July/036318.html I haven't done much looking into this, but for your question, I believe the two option that control the size of objects on disk are the "rgw_obj_stripe_size", and the k value of the EC pool. rgw_obj_stripe_size (4MB) is the maximum size of a rados object that the RGW will create, so an S3 object larger than 4MB will be split into 4MB rados objects. An S3 object smaller than 4MB will not be padded as far as I know, and will exist as a single rados object of the same size as the S3 object. There is also a rgw_max_chunk_size parameter, but I'm not completely sure how it relates. I think S3 objects are striped and then chunked, so rgw_max_chunk_size = rgw_obj_stripe_size = 4MB results in 4MB rados objects. The K value of the EC pool defines the number of shards into which the rados object is split. In this case a k=10 will result in the shards on disk being 400KB ( 4MB / 10 ) or smaller. Cheers, Tom > -----Original Message----- > From: Biswajeet Patra <biswajeet.patra@xxxxxxxxxxxx> > Sent: 11 May 2020 12:51 > To: ceph-users@xxxxxxx > Cc: Priya Sehgal <priya.sehgal@xxxxxxxxxxxx> > Subject: Erasure coded pool queries > > Hi, > I have created an erasure coded pool and the below default parameters > related to stripe sizes are present. > "osd_pool_erasure_code_stripe_width": "4096" --> 4KB > "rgw_obj_stripe_size": "4194304" --> 4MB Let say the k+m values are 10+5 > for the erasure pool, and we upload an object of let say, size <4MB & another > object of size >4MB. How will ceph break the object into chunks and store it & > how many stripes will be created? > > Regards, > Biswajeet > > -- > > > > *-----------------------------------------------------------------------------------------* > > > *This email and any files transmitted with it are confidential and intended > solely for the use of the individual or entity to whom they are addressed. If > you have received this email in error, please notify the system manager. This > message contains confidential information and is intended only for the > individual named. If you are not the named addressee, you should not > disseminate, distribute or copy this email. Please notify the sender > immediately by email if you have received this email by mistake and delete > this email from your system. If you are not the intended recipient, you are > notified that disclosing, copying, distributing or taking any action in reliance on > the contents of this information is strictly prohibited.***** > > **** > > *Any views or opinions presented in this email are solely those of the author > and do not necessarily represent those of the organization. Any information > on shares, debentures or similar instruments, recommended product pricing, > valuations and the like are for information purposes only. It is not meant to be > an instruction or recommendation, as the case may be, to buy or to sell > securities, products, services nor an offer to buy or sell securities, products or > services unless specifically stated to be so on behalf of the Flipkart group. > Employees of the Flipkart group of companies are expressly required not to > make defamatory statements and not to infringe or authorise any > infringement of copyright or any other legal right by email communications. > Any such communication is contrary to organizational policy and outside the > scope of the employment of the individual concerned. The organization will > not accept any liability in respect of such communication, and the employee > responsible will be personally liable for any damages or other liability > arising.***** > > **** > > *Our organization accepts no liability for the content of this email, or for the > consequences of any actions taken on the basis of the > information *provided,* unless that information is subsequently confirmed in > writing. If you are not the intended recipient, you are notified that disclosing, > copying, distributing or taking any action in reliance on the contents of this > information is strictly > prohibited.* > > > _-----------------------------------------------------------------------------------------_ > > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to > ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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