Differences

This shows you the differences between two versions of the page.

--- unix:iscsi:advanced [2026/02/02 01:44] – removed - external edit (Unknown date) 127.0.0.1
+++ unix:iscsi:advanced [2026/02/02 01:44] (current) – ↷ Page moved from unix:advanced to unix:iscsi:advanced rodolico
@@ Line 1: / Line 1: @@
+====== Advanced iSCSI Procedures ======
+This article covers non-trivial iSCSI procedures that require careful execution to avoid data loss or service disruption.
+===== Resizing an iSCSI Target =====
+==== Overview ====
+When an iSCSI target needs to be expanded, the process varies depending on the underlying storage technology. This guide covers both LVM2 and ZFS-based targets.
+==== General Approach (LVM2) ====
+For LVM2-backed exports:
+  - Unmount and disconnect the target on all initiators
+  - Expand the logical volume on the target server
+  - Restart the iSCSI target service (recommended for consistency)
+  - Reconnect initiators and resize the filesystem
+==== ZFS-Based Targets (FreeBSD) ====
+The following procedure assumes:
+  * **Target:** FreeBSD with ZFS volumes (zvols)
+  * **Initiator:** Debian/Devuan-based Linux systems
+<WRAP center round alert 60%>
+**⚠ Warning:** Ensure no applications or services are accessing the target volume during this process. Options:
+  * **Minimum:** Stop all services using the target
+  * **Recommended:** Logout from the target on all initiators before making changes
+</WRAP>
+=== Step 1: Expand the ZFS Volume (Target Server) ===
+<code bash>
+# Set the new size on the ZFS volume
+# Example: storage/iscsi/target is the zvol path
+# newsize format: 500G, 2T, etc.
+zfs set volsize=500G storage/iscsi/target
+# Notify ctld of the configuration change
+# 'reload' may work instead of 'restart' if supported
+service ctld restart
+</code>
+=== Step 2: Rescan from Initiator (Linux) ===
+After expanding the target, initiators must rescan to detect the new size.
+**Option A: Rescan all sessions (not recommended for production)**
+<code bash>
+# Rescans ALL iSCSI sessions - use with caution in production
+iscsiadm -m session --rescan
+</code>
+**Option B: Rescan specific target only (recommended)**
+<code bash>
+# Method 1: Find the Session ID (SID) for your specific target
+# Replace 'thing1' with a unique substring from your target name
+SID=$(iscsiadm -m session -P 0 | grep thing1 | cut -d'[' -f2 | cut -d']' -f1)
+# Rescan only that specific session
+iscsiadm --mode session --sid=$SID --rescan
+# Alternatively, manually find SID and run directly:
+# iscsiadm -m session          # Lists all sessions with SIDs
+# iscsiadm --mode session --sid=15 --rescan
+# Verify the new size has been detected
+fdisk -l /dev/disk/by-path/ip-<target-ip>:3260-iscsi-<iqn>-lun-<num>
+# Or use lsblk for a cleaner view
+lsblk /dev/disk/by-path/ip-<target-ip>*
+</code>
+=== Step 3: Resize the Filesystem ===
+After the initiator recognizes the new size, expand the filesystem:
+**For ext4:**
+<code bash>
+resize2fs /dev/sdX
+</code>
+**For XFS:**
+<code bash>
+xfs_growfs /mount/point
+</code>
+**For LVM:**
+<code bash>
+pvresize /dev/sdX
+lvextend -l +100%FREE /dev/vg_name/lv_name
+resize2fs /dev/vg_name/lv_name  # for ext4
+</code>
+**For virtual machines:** Consider booting from [[https://gparted.org/download.php|GParted Live CD]] to safely resize partitions without mounting them.
+===== Removing an iSCSI Target =====
+==== Overview ====
+Removing an iSCSI target requires cleanup on both the target server and all initiators. The initiator maintains a local database of discovered targets that must be explicitly cleaned.
+<WRAP center round important 60%>
+**Critical:** Always logout from the target BEFORE removing it from the database. Failure to do so may cause issues.
+</WRAP>
+==== Procedure: Remove a Single Target ====
+<code bash>
+# Step 1: Logout from the iSCSI session
+# Replace with your actual target IQN and portal address
+iscsiadm -m node \
+  --target='iqn.2005-03.org.example:storage.target1' \
+  --portal "192.168.1.100:3260" \
+  --logout
+# Step 2: Remove the target from the local database
+iscsiadm -m node \
+  --target='iqn.2005-03.org.example:storage.target1' \
+  --portal "192.168.1.100:3260" \
+  -o delete
+# Verify removal
+iscsiadm -m node
+</code>
+==== Procedure: Remove All Targets (Complete Cleanup) ====
+When decommissioning an entire iSCSI infrastructure or target server:
+=== Method 1: Service Shutdown and Manual Cleanup ===
+<code bash>
+# Stop the iSCSI initiator service
+# sysV (Devuan, other good Linux systems)
+service start iscsiadm
+service stop open-iscis # or iscsid on some systems
+# systemd (RedHat, other Linux systems which have drunk the Kool-aid)
+systemctl stop iscsiadm
+systemctl stop open-iscsi    # or iscsid on some systems
+# Remove iSCSI configuration databases
+# Debian/Ubuntu location:
+rm -rf /etc/iscsi/send_targets/*
+rm -rf /etc/iscsi/nodes/*
+# RHEL/CentOS/Rocky location:
+rm -rf /var/lib/iscsi/send_targets/*
+rm -rf /var/lib/iscsi/nodes/*
+# Restart the service
+service start open-iscis # sysV
+systemctl start open-iscsi # systemd
+</code>
+=== Method 2: Programmatic Logout ===
+<code bash>
+# Logout from all active sessions
+iscsiadm -m node --logoutall=all
+# Remove all node records
+iscsiadm -m node -o delete
+# Verify all targets are removed
+iscsiadm -m node
+</code>
+==== Distribution-Specific Notes ====
+^ Distribution ^ Configuration Path ^
+| Debian/Ubuntu/Devuan | ''/etc/iscsi/nodes/'' and ''/etc/iscsi/send_targets/'' |
+| RHEL/CentOS/Rocky/Fedora | ''/var/lib/iscsi/nodes/'' and ''/var/lib/iscsi/send_targets/'' |
+| SUSE | ''/var/lib/iscsi/nodes/'' and ''/var/lib/iscsi/send_targets/'' |
+===== Additional Resources =====
+  * [[https://linux.die.net/man/8/iscsiadm|iscsiadm man page]]
+  * [[https://docs.freebsd.org/en/books/handbook/network-iscsi/|FreeBSD iSCSI Handbook]]
+  * [[https://groups.google.com/forum/#!topic/open-iscsi/7x28lO6-Rho|Open-iSCSI Google Group Discussion]]
+===== Best Practices =====
+  * Always test resize operations in a non-production environment first
+  * Maintain backups before performing any resize operations
+  * Document your target IQNs and portal addresses
+  * Use ''by-path'' device naming for consistency across reboots
+  * Monitor initiator logs (''/var/log/syslog'' or ''journalctl'') during operations
+----
+//Last updated: February 2, 2026//