baiyao...@cmss.chinamobile.com Bcc: Subject: COMPARE_AND_WRITE support for rbd driver Reply-To: baiyao...@cmss.chinamobile.com
Hey guys, I noticed that COMPARE_AND_WRITE had been supported by CEPH/librbd since v12.1.1. And in my company, we use this COMPARE_AND_WRITE support in CEPH with the ISCSI protocol. More precisely, we use tgt and CEPH with this COMPARE_AND_WRITE support as the SCSI target and export it to the remote hosts. And then VMs on remote hosts can use these SCSI targets through ISCSI initiator support in QEMU directly or as local SCSI disks. But unfortunately, there're some issues with this tgt case. So i think maybe we could also add this COMPARE_AND_WRITE support into the rbd driver in QEMU so we can leave the ISCSI/tgt alone and use this COMPARE_AND_WRITE support with the scsi-disk <--> virtio-scsi <--> rbd driver path. This can also apply to the WRITESAME support in CEPH/librbd. So is it suitable for doing this? I want to hear suggestions from you genius guys. Appreciate it.
