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--- unix:linux:iscsi_tricks_and_techniques [2016/09/06 19:57] – external edit 127.0.0.1
+++ unix:linux:iscsi_tricks_and_techniques [2025/11/27 17:15] (current) – [Resizing your target] rodolico
@@ Line 22: / Line 22: @@
 ===== Tricks and Techniques =====
+==== Script to update all targets ====
+For some reason, I'm occasionally a little out of sync between what my target offers and what my initiator knows about. The following script will not //remove// anything, but it will add every target offered by the iscsi target.
+Add one or more entries into @servers, and it will scan the targets in question, then compare against what our initiator knows, then add any new entries.
+<code perl addAlliSCSIS.pl>
+#! /usr/bin/env perl
+use strict;
+use warnings;
+# change following to be a list of 1 or more iSCSI targets to be queried
+my @servers = ( '10.10.10.10','10.10.10.9' );
+my %targets;
+foreach my $server ( @servers ) {
+   print "\n" . '-'x40 . "\nGetting targets on server $server\n" . '-'x40 . "\n";
+   my @list = `iscsiadm -m discovery -t st -p $server`;
+   chomp @list;
+   # @list contains lines of type
+   # 10.19.209.2:3260,1 iqn.2014-11.net.dailydata.castor:simon0
+   # split them apart and add them to the hash
+   foreach my $entry ( @list ) {
+      my ( $portal, $targetName ) = split( ' ', $entry );
+      # $portal has some extra info after a comma, so clean it up
+      $portal =~ m/^([0-9:.]+)/;
+      $portal = $1;
+      # some targets return multiple IP's for a given name, so
+      # only add them if they are in this IP
+      $targets{ $targetName } = $portal if $portal =~ m/^$server/;
+      print "$targetName\t$targets{ $targetName }\n";
+   }
+}
+print "\n" . '-'x40 . "\nGetting active sessions\n". '-'x40 . "\n";
+# now, get active sessions so we can filter them
+my @activeSessions = `iscsiadm -m session`;
+chomp @activeSessions;
+foreach my $session ( @activeSessions ) {
+   $session =~ m/^.*[^0-9:.]([0-9,:.]+).*(iqn\S*)/;
+   my ( $portal,$targetName ) = ( $1,$2 );
+   print "$portal\t$targetName";
+   if ( exists( $targets{$targetName} ) ) {
+      print "\tNOT updating\n";
+      delete $targets{ $targetName };
+   } else {
+      print "Needs to be added\n";
+   }
+}
+# check if we have any new entries and bail if not
+if ( scalar keys %targets ) {
+   # We have new entries, so run them;
+   foreach my $targetName ( sort keys %targets ) {
+      my $portal = $targets{$targetName};
+      print "Adding $targetName\n";
+      `iscsiadm -m node --targetname '$targetName' --portal '$portal' --login`;
+   }
+} else {
+   print "No new entries\n";
+}
+# print `ls /dev/disk/by-path/`;
+</code>
+==== Fixing bolluxed machine ====
+Ok, your initiator is in a really bad shape, or you did something on the target you shouldn't have, and you want to basically reinitialize everything. But, you don't want to shut everything down. This was the procedure I used to do so. I migrated all of my Xen devices onto a different machine, then ran the following on the machine I wanted to reinitialize:
+<code bash>
+/etc/init.d/open-iscsi stop
+rm -fR /etc/iscsi/send_targets/* /etc/iscsi/nodes/*
+/etc/init.d/open-iscsi start
+/media/xen-store/scripts/addAlliSCIS.pl
+</code>
+**Note**: This is on an old Debian Wheezy machine, so start/stop commands are different after that.
+The first line stops the initiator. The second line removes all remembered connections from the initiators cache, then we start the initiator again.
+At this point, we don't "know" any targets, so we use the script (above) to grab all targets available on the iscsi target. YEAH, we're done.
 ==== Viewing targets exported from a target device, from the target device ====
@@ Line 37: / Line 121: @@
 </code>
-Edit /etc/iet/ietd.conf and add the following lines
+Edit /etc/iet/ietd.conf (Linux) or /etc/ctl.conf (BSD) and add the following lines
 <code>
@@ Line 45: / Line 129: @@
 </code>
 Restart iet
-<code bash>  /etc/init.d/iscsitarget restart</code>
+<code bash>/etc/init.d/iscsitarget restart # Linux
+service ctld reload # FreeBSD
+</code>
 ==== Adding new target to initiator ====
@@ Line 77: / Line 163: @@
 Ok, you messed up and the target is too small. If you are using LVM2 partitions for your exports (good idea), simply take it offline on the initiators, then add space on the target. Now (and I'm not sure this is required), restart iscsi on the target.
-When you modify a target on the iSCSI target, it is not automatically updated on the initiator. You could simply restart openiscsi or, if you just want to get the new size of one target, log out and the log in again from the initiator.
+However, I generally use a FreeBSD target (with ZFS on it, setting the targets to Volumes). Following assumes you are using FreeBSD ZFS Volumes for your target, and Devuan (Debian) on your initiator.
+<WRAP center round alert 60%>
+Warning: Do not allow anything to access the target during this process. You can probably get by with just shutting down anything which accesses it. Or, for the paranoid amongs us, logout of the target from your initiator, do the work, then log back in.
+</WRAP>
+=== On FreeBSD target ===
 <code bash>
-# log out, then back into target
+# set the new size on the target (assumed to be /storage/iscsi/target in example(
-iscsiadm -m node --target='name of target' --portal "ip:port" --logout\\ iscsiadm -m node --target='name of target' --portal "ip:port" --login
+zfs set quota=<newsize> storage/iscsi/target
+# let ctld know about the change. reload may work instead of restart
+service ctld restart
 </code>
-The size of the target should now be updated (hint, //fdisk -l /dev/disk/bypath/somename// is your friend)
+=== On initiator ===
+You now need to rescan the target from the initiators. The first example rescans everything, which may not be what you want.
+<code bash>
+# probably not the best, since it rescans everything.
+# see next code block.
+iscsiadm -m session --rescan
+</code>
+Better to only scan the one you actually changed. This assumes the target has the substring //thing1// in it.
+<code bash>
+# find the Session ID of the target in question.
+# NOTE: that you can just do iscsiadm -m session for the whole
+# list and manually find the SID (number surrounded by square brackets)
+iscsiadm -m session -P 0 | grep thing1 | cut -d'[' -f2 | cut -d']' -f 1
+# now, rescan only that SID (that one target)
+iscsiadm --mode session --sid=15 --rescan
+# use any tool you like to check the new size. I use fdisk -l, which will
+# return the size on the first line
+fdisk -l /dev/disk/by-path/ip-.....
+</code>
+At this point, your size it set correctly (we hope). Now, you need to resize the file system which is different depending on which file system it is. For virtuals, I generally boot from the gparted live CD (https://gparted.org/download.php) to avoid any problems.
 ==== Remove a target ====
@@ Line 92: / Line 211: @@
 # first, log out of the session
 iscsiadm -m node --target='name of target' --portal "ip:port" --logout
-# now, do a discovery and delete the entry from your local database
+# now, do a remove it from the session
-iscsiadm -m discovery --target='name of target' --portal "ip:port" -o delete
+iscsiadm -m node --target='name of target' --portal "ip:port" -o delete
 </code>