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soc:2009:pravin:journal:bkodebianiscsi [2009/07/18 11:25]
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soc:2009:pravin:journal:bkodebianiscsi [2009/09/25 19:37] (current)
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   - Executed above commands from inside live CD   - Executed above commands from inside live CD
   - The ''​iscsiadm -m discovery''​ command did gave output.   - The ''​iscsiadm -m discovery''​ command did gave output.
 +<​code>​
 +# iscsiadm -m discovery -t st -p 192.168.0.1
 +192.168.0.1:​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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