Signed-off-by: Hitoshi Mitake <mitake.hitoshi@xxxxxxxxxxxxx> --- doc/README.sheepdog | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 doc/README.sheepdog diff --git a/doc/README.sheepdog b/doc/README.sheepdog new file mode 100644 index 0000000..64452fe --- /dev/null +++ b/doc/README.sheepdog @@ -0,0 +1,100 @@ +Sheepdog is a distributed storage system for QEMU, iSCSI clients and +RESTful services. It provides highly available block level storage +volumes that can be attached to QEMU-based virtual machines. The +volumes can also be attached to other virtual machines and operating +systems run on baremetal hardware if they support iSCSI +protocol. Sheepdog scales to several hundreds nodes, and supports +advanced volume management features such as snapshot, cloning, and +thin provisioning. Stuff like volumes, snapshots, QEMU's vm-state +(from live snapshot), even ISO files can be stored in the Sheepdog +cluster. + +With tgt, sheepdog's virtual disks can be used by iSCSI +initiators. Below is a brief description of setup. + +1. Install and launch tgt + +$ git clone https://github.com/fujita/tgt.git +$ cd tgt +$ make +# make install +2. Create a sheepdog VDI + +There is no special procedures in this step. + +$ dog vdi create tgt0 100G +Of course you can use existing VDIs as iSCSI logical units. + +3. Setup iSCSI target provided by tgt + +One logical unit corresponds to one VDI of sheepdog. In this step, we +create iSCSI target and logical unit which can be seen by iSCSI +initiator. + +# tgtd +# tgtadm --op new --mode target --tid 1 --lld iscsi --targetname iqn.2013-10.org.sheepdog-project +# tgtadm --op new --mode lu --tid 1 --lun 2 --bstype sheepdog --backing-store unix:/sheep_store/sock:tgt0 +# tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL + +The most important parameter is --backing-store which is required by +tgtadm when we create the logical unit in the target (the third line +of the above commands). With this parameter, we tell the tgtd +process how to connect to the sheep process, which VDI we use as the +logical unit, which snapshot ID of the VDI we use. The form of the +--backing-store option is like this: + + unix:path_of_unix_domain_socket:vdi + unix:path_of_unix_domain_socket:vdi:tag + unix:path_of_unix_domain_socket:vdi:snapid + tcp:host:port:vdi + tcp:host:port:vdi:tag + tcp:host:port:vdi:snapid + +We use a special case of the first one in the above command +sequence. It means "connect to sheep process via unix domain socket +protocol, path of unix domain socket is /sheep_store/sock, use VDI +named tgt0 as a backing store of newly created logical unit". + +You can also specify sheep which is running on remote host via +TCP. But if tgtd process is running on a same host of sheep process, +there is no benefit of using TCP. Unix domain socket can provide +faster connection than TCP. + +You can also specify tag or ID of snapshots via suffix of the +--backing-store option. + +4. Setup iSCSI session (example of the open-iscsi initiator on Linux) + +After setting up iSCSI target, you can use the VDIs from any virtual +machines and operating systems which supports iSCSI initiator. Many of +popular hypervisors and operating systems support it (e.g. VMware ESX +Family, Linux, Windows, etc). In this example, the way of Linux + +open-iscsi is described. + +At first, you have to install open-iscsi ( http://www.open-iscsi.org/ +) and launch it. Major linux distros provide their open-iscsi +package. Below is a way of installation in Debian and Ubuntu based +systems. + +# apt-get install open-iscsi +# /etc/init.d/open-iscsi start + +Next, we need to let iscsid discover and login to the target we've +already created in the above sequence. If the initiator is running +on different host from the target, you have to change the IP +addresses in the below commands. + +# iscsiadm -m discovery -t st -p 127.0.0.1 +# iscsiadm -m node --targetname iqn.2013-10.org.sheepdog-project --portal 127.0.0.1:3260 --login + +New device files, e.g. /dev/sdb, will be created on your system after +login completion. Now your system can use the speepdog VDIs like +ordinal HDDs. + +ToDo + +Currently, iSCSI multipath is not supported by sheepdog. It will be +implemented in v0.9.0. + +The latest version of this guide can be found here: +https://github.com/sheepdog/sheepdog/wiki/General-protocol-support-%28iSCSI-and-NBD%29 -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
