About me: My name is Solène Rapenne. I like learning and sharing my knowledge related to IT stuff. Hobbies: '(BSD OpenBSD h+ Lisp cmdline gaming internet-stuff Crossbow). I love percent and lambda characters. OpenBSD developer solene@.

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OpenBSD and iSCSI part2: the initiator (client)

Written by Solène, on 21 February 2019.
Tags: #unix #openbsd #iscsi

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This is the second article of the serie about iSCSI. In this one, you will learn how to connect to an iSCSI target using OpenBSD base daemon iscsid.

The configuration file of iscsid doesn’t exist by default, its location is /etc/iscsi.conf. It can be easily written using the following:


target "disk1" {
    initiatoraddr $myaddress
    targetaddr $target1
    targetname "iqn.1994-04.org.netbsd.iscsi-target:target0"

While most lines are really obvious, it is mandatory to have the line initiatoraddr, many thanks to cwen@ for pointing this out when I was stuck on it.

The targetname value will depend of the iSCSI target server. If you use netbsd-iscsi-target, then you only need to care about the last part, aka target0 and replace it by the name of your target (which is target0 for the default one).

Then we can enable the daemon and start it:

# rcctl enable iscsid
# rcctl start iscsid

In your dmesg, you should see a line like:

sd4 at scsibus0 targ 1 lun 0: <NetBSD, NetBSD iSCSI, 0> SCSI3 0/direct fixed t10.NetBSD_0x5c6cf1b69fc3b38a

If you use netbsd-iscsi-target, the whole line should be identic except for the sd4 part which can change, depending of your hardware.

If you don’t see it, you may need to reload iscsid configuration file with iscsictl reload.

Warning: iSCSI is a bit of pain to debug, if it doesn’t work, double check the IPs in /etc/iscsi.conf, check your PF rules on the initiator and the target. You should be at least able to telnet into the target IP port 3260.

Once you found your new sd device, you can format it and mount it as a regular disk device:

# newfs /dev/rsd4c
# mount /dev/sd4c /mnt

iSCSI is far mor efficient and faster than NFS but it has a total different purpose. I’m using it on my powerpc machines to build packages on it. This reduce their old IDE disks usage while giving better response time and equivalent speed.

OpenBSD and iSCSI part1: the target (server)

Written by Solène, on 21 February 2019.
Tags: #unix #openbsd #iscsi

Comments on Mastodon

This is the first article of a series about iSCSI.

iSCSI is a protocol designed for sharing a block device across network as if it was a local disk. This doesn’t permit using that disk from multiples places at once though. In this article, we will learn how to create an iSCSI target, which is the “server” part of iSCSI, the target is the system holding the disk and making it available to others on the network.

OpenBSD does not have an target server in base, we will have to use net/netbsd-iscsi-target for this. The setup is really simple.

First, we obviously need to install the package and we will activate the daemon so it start automatically at boot, but don’t start it yet:

# pkg_add netbsd-iscsi-target
# rcctl enable iscsi_target

The configurations files are in /etc/iscsi/ folder, it contains files auths and targets. The default configuration files are the same. By looking at the source code, it seems that auths is used there but it seems to have no use at all. We will just overwrite it everytime we modify targets to keep them in sync.

Default /etc/iscsi/targets (with comments stripped):

extent0         /tmp/iscsi-target0      0       100MB
target0         rw      extent0

The first line defines the file holding our disk in the second field, and the last field defines the size of it. When iscsi-target will be started, it will create files as required with the size defined here.

The second line defines permissions, in that case, the extent0 disk can be used read/write by the net For this example, I will only change the netmask to suit my network, then I copy targets over auths.

Let’s start the daemon:

# rcctl start iscsi_target
# rcctl check iscsi_target

If you want to restrict ports using PF, you only have to allows the TCP port 3260 from the network that will connect to the target. The according line would looks like this:

pass in proto tcp to port 3260