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--- soc:2009:pravin:journal:bkodebianiscsi [2009/07/18 10:53]
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+++ soc:2009:pravin:journal:bkodebianiscsi [2009/09/25 19:37] (current)
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@@ Line 106: / Line 106: @@
 $ ls mpoint
 doc  isolinux  live  md5sum.txt
+</code>
+As Now I know that my target is working correctly, I am free to try out booting from this target 8-)
+===== Configuring initramfs as initiator =====
+I need to add all the tools, configuration files and kernel modules to initramfs so that I can use them from there to connect.
+  * ** Step 1 **, __Kernel Modules__ : on checking the contents of ''/etc/init.d/open-iscsi'' it seems that following kernel modules are to be inserted
+<code>
+modprobe iscsi_tcp
+modprobe ib_iser
+</code>
+  * These modules are already in debian initramfs, so no need to worry about that :)
+  * ** Step 2 ** __Tools needed__ : Again ''/etc/init.d/open-iscsi'' tells us that it uses ''/sbin/iscsid'' and ''/sbin/iscsiadm''\\
+but there are more iscsi related tools in /sbin
+<code>
+$ ls /sbin/iscsi*
+/sbin/iscsiadm  /sbin/iscsid  /sbin/iscsi_discovery  /sbin/iscsi-iname  /sbin/iscsistart
+</code>
+To avoid any missing dependencies, better to add all above tools to initramfs.
+  * ** Step 3 ** __Configuration Files__ : From man page of iscsiadm and iscsid, we can guess that following configuration files will be needed
+<code>
+/etc/iscsi/iscsid.conf
+/etc/iscsi/initiatorname.iscsi
+</code>
+===== Testing new initramfs =====
+The HTTPFS code has been commented out so that initramfs will give me rescue shell, which can be used to start the iscsi initiator.\\
+Following commands were executed once the rescue shell is provided.
+<code>
+modprobe iscsi_tcp
+modprobe ib_iser
+mkdir /var/run
+/sbin/iscsid
+iscsiadm -m discovery -t st -p 192.168.0.1
+</code>
+and no node is shown :(\\
+I tried to run iscsid in debug mode with following command
+<code>
+/sbin/iscsid -d 8 -f
+iscsid : sysfs_init: sysfs_path='/sys'
+[...]
+[...]
+iscsid: reaped pid 994, reap_count now 0
+</code>
+and also ran ''iscsiadm'' in debug mode with following output
+<code>
+(initramfs) iscsiadm -d 8 -m discovery -t st -p 192.168.0.1
+iscsiadm: ip 192.168.0.1, port 3260, tgpt -1
+iscsiadm: Max file limits 1024 1024
+</code>
+This output is definitely very less compare to the output of same command executed on my laptop.\\
+**Note:** __This was executed over qeum.__ I am not sure if qemu has created any problem.
+===== Debugging the problem =====
+To make sure debien in virtual environment can use iscsi with the tools, and configuration files used inside initramfs\\
+  - I booted debian live CD with virtualbox
+  - inserted kernel modules just as above
+  - Copied configuration files into live cd.
+  - Copied tools into live cd
+  - Executed above commands from inside live CD
+  - The ''iscsiadm -m discovery'' command did gave output.
+<code>
+# iscsiadm -m discovery -t st -p 192.168.0.1
+.168.0.1:3260,1 iqn.2001-04.com.example:storage.lun1
+</code>
+So, the tools do work. but may be they are able to use other files, tools and modules which are not present in initrd.\\
+How to find those dependencies?
+===== Debugging v2 =====
+Finally, added the ''strace'' to initramfs, and now trying find what is the problem because of which iscsiadm is dying\\
+<code>
+socket(PF_FILE, SOCK_STREAM, 0)         = 3
+connect(3, {sa_family=AF_FILE, path=@"ISCSIADM_ABSTRACT_NAMESPACE"...}, 110) = 0
+write(3, "\n\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 5244) = -1 EPIPE (Broken pipe)
+</code>
+This is what killing the iscsiadm imatuarly.
+==== Checking the code of open-iscsi ====
+With help of stephana, the likely problem is located at following location
+<code>
+stefanha: http://git.kernel.org/?p=linux/kernel/git/mnc/open-iscsi.git;a=blob;f=usr/mgmt_ipc.c;h=e784bcac019a84522e62beff1b49b1ca62e37f5a;hb=HEAD
+(07/19/2009 04:34:21 PM) stefanha: less1: Perhaps you're hitting this:
+(07/19/2009 04:34:27 PM) stefanha: http://git.kernel.org/?p=linux/kernel/git/mnc/open-iscsi.git;a=blob;f=usr/mgmt_ipc.c;h=e784bcac019a84522e62beff1b49b1ca62e37f5a;hb=HEAD#l549
+(07/19/2009 04:34:31 PM) stefanha: if (!mgmt_peeruser(fd, user) || strncmp(user, "root", PEERUSER_MAX)) {
+(07/19/2009 04:34:43 PM) stefanha: write(2) will return EPIPE if the UNIX domain socket was closed.
+(07/19/2009 04:35:17 PM) stefanha: mgmt_peeruser() is defined here: http://git.kernel.org/?p=linux/kernel/git/mnc/open-iscsi.git;a=blob;f=usr/mgmt_ipc.c;h=e784bcac019a84522e62beff1b49b1ca62e37f5a;hb=HEAD#l342
+(07/19/2009 04:38:15 PM) less1: stefanha: is it checking if I have root privilages? I am not sure if I understand which peeruser credential is it refering.
+(07/19/2009 04:40:08 PM) stefanha: Your user name must be "root".
+(07/19/2009 04:40:25 PM) stefanha: Otherwise iscsid will not accept commands from the UNIX domain socket.
+</code>
+=== Possible solution : hacking open-iscsi ===
+modified the ''iscsiadm'' code so that, it will not fail when username is not ''root''.\\
+With is modification, the discovery part is working, but now there is error at login part. Following is the error.
+<code>
+connection2:0: Could not create connection due to crc32c loading error.  Make sure the crc32c module is build as module into the kernel.
+</code>
+The first attempt will be to download the kernel module from Live CD of debian after booting it from CD.\\
+--- Doing it
+===== Working Solution =====
+There was need for two extra kernel modules
+  - libcrc32c.ko
+  - crc32c.ko
+Fetched these modules from live-CD and added them.\\
+There as also need for small sleep after ''iscsiadm --login'' as ''/dev/sda'' was taking little time to appear.\\
+This was handled by adding ''sleep 2''\\
+Two new parameters were introduced
+  - ''iscsifs=<IP:PORT>''  iscsi server IP and port number
+  - ''target=<targetname>'' the iscsi target name of the disk (entire name is not needed, some part which can uniquely identify apart from other disks exported at same machine)
+===== Remote ISCSI =====
+Following are the errors that I get when connecting to remote iscsi
+<code>
+Connection1:0: ping timeout of 5 secs expired, last rx 307737, last ping 308987, now 310237
+Connection1:0: detected conn error (1011)
+SQUASHFS error : Unable to read page, block 0x1b392
+Bus error
+</code>
+Most of these errors are related to timing, and I believe that
+these errors are there because of delays in accessing required data.
+===== Target behaviour =====
+sometimes, you may get following error when logging in with iscsiadm
+<code>
+iscsiadm -m node --targetname "${targetname}" --portal "${ISCSIFS}" --login
+records not found!.
+</code>
+this is because the ${ISCSIFS} is not IP but dnsname.
+Dnsname may work with ''iscsiadm -m discovery -t st -p "${ISCSIFS}" ''
+but it may verywell fail when same dnsname is given to login.
+[[http://groups.google.com/group/open-iscsi/browse_thread/thread/c556508505ecc461|mailing list discussion]]
+==== Solution ====
+Dont use ''--portal "${ISCSIFS}"'' option, use
+<code>
+iscsiadm -m node --targetname "${targetname}" --login
 </code>

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