I might be wrong but the object size is 4M in ceph so this might be the case also. But yeah, on the lower level of data storing I'm not familiar. Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@xxxxxxxxx --------------------------------------------------- -----Original Message----- From: Pawel S <pejotes@xxxxxxxxx> Sent: Tuesday, March 2, 2021 1:34 AM To: ceph-users@xxxxxxx Subject: [Suspicious newsletter] RBD clone on Bluestore Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________ hello! I'm trying to understand how Bluestore cooperates with RBD image clones, so my test is simple 1. create an image (2G) and fill with data 2. create a snapshot 3. protect it 4. create a clone of the image 5. write a small portion of data (4K) to clone 6. check how it changed and if just 4K are used to prove CoW allocated new extent instead of copying out snapped data. Unfortunately it occurs that at least rbd du reports that 4M was changed and the clone consumes 4M of data instead of expected 4K... ''' rbd du rbd/clone1 NAME PROVISIONED USED clone1 2 GiB 4 MiB ''' How can I trace/prove Bluestore CoW really works in this case, and prevent copying the rest of the 4M stripe like Filestore did ? p.s tested on Luminous/Octopus, ssd devices, min_alloc_size: 16k, block_size: 4k best regards! -- Pawel S. _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx ________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses. _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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