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(a)agoda.com
---------------------------------------------------
-----Original Message-----
From: Pawel S <pejotes(a)gmail.com>
Sent: Tuesday, March 2, 2021 1:34 AM
To: ceph-users(a)ceph.io
Subject: [Suspicious newsletter] [ceph-users] 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(a)ceph.io To unsubscribe send an email to
ceph-users-leave(a)ceph.io
________________________________
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.