Hello, I am not an expert in CEPH.
However, iSCSI is the transport protocols to connect an initiator to a target. On the client side, iSCSI traffic coming from target is broken down and the SCSI commands are handed to the client. When writing data, the iSCSI initiator encoded the command and data and transports it to the iSCSI target where the target breaks down the iSCSI portion to get the client SCSI command, I.e. a WRITE10, and processes that request. So things like CEPH are above the iSCSI layer. This is why CEPH can work with Fibre Channel, SAS, SCSI, iSCSI, etc... https://docs.ceph.com/docs/mimic/glossary/#term-ceph-osd-daemon OSD A physical or logical storage unit (*e.g.*, LUN). Sometimes, Ceph users use the term “OSD” to refer to Ceph OSD Daemon <https://docs.ceph.com/docs/mimic/glossary/#term-ceph-osd-daemon>, though the proper term is “Ceph OSD”. So iSCSI will provide the physical LUN that CEPH will use. This is good otherwise for every protocol of storage you want to use, you would have to have a specific driver for CEPH. This is a pretty good intro to iSCSI https://blog.calsoftinc.com/2017/03/iscsi-introduction-steps-configure-iscsi-initiator-target.html Regards, Don On Fri, Jan 24, 2020 at 4:50 PM Bobby <[email protected]> wrote: > Hi, > > I have some questions regarding iSCSI and Ceph RBD. If I have understood > correctly, the RBD backstore module > on target side can translate SCSI IO into Ceph OSD requests. The iSCSI > target driver with rbd.ko can expose Ceph cluster > on iSCSI protocol. If correct, then that all is happening on target side. > > My confusion is what is happening on client side? > > Meaning, does linux mainline kernel code called "rbd" has any role with > Open-iSCSI initiator on client side? To put it more simple, > is there any common ground for both protocols (iSCSI and rbd) in the linux > kernel of the client side? > > Thanks :-) > > -- > You received this message because you are subscribed to the Google Groups > "open-iscsi" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/open-iscsi/dc5e17db-5e78-49ff-be38-a17706428655%40googlegroups.com > <https://groups.google.com/d/msgid/open-iscsi/dc5e17db-5e78-49ff-be38-a17706428655%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/open-iscsi/CAK3e-EYmEN1ETc_Ru0xcuaKUisDSV0B2%3Ded2Kx9Wk2rksAXnQg%40mail.gmail.com.
