--- name: BlockStorage-identify_LUNs title: Identifying Logical Unit Number IDs (LUN IDs) description: Learn how to look up the logical unit number (LUN) ID of attached Block Storage for Classic volumes on your compute host. last-updated: 2026-08-06 --- > ## Documentation Index > The table of contents for this documentation set is at https://cloud.ibm.com/docs/BlockStorage?format=markdown > The index for all IBM Cloud docs is at: https://cloud.ibm.com/docs/llms.txt > Use these files to discover more information as needed. # Identifying Logical Unit Number IDs (LUN IDs) {: #identifyLUN} Learn how to look up the logical unit number (LUN) ID of attached Block Storage for Classic volumes on your compute host. {: shortdesc} In Storage Area Networks (SAN), a Logical Unit Number (LUN) is a unique identifier that is assigned to a logical block of storage. LUNs allow servers to identify, access, and manage specific virtual partitions or physical hard disks across a network. Various reasons exist for why you would want to look up the LUN ID of the attached storage volumes on the Compute host. For example, you can have multiple storage devices that are mounted on the same host with the same volume sizes. You want to detach and decommission one of them. However, you are not sure how to correlate what you see on your Linux® host with what you see in the IBM Cloud console. Another example is when you have multiple Block Storage for Classic volumes that are attached to an ESXi server. You want to expand the volume size of one of the LUNs, and you need to know the correct LUN ID of the storage to do that. ## Viewing the LUN ID in Linux® {: #identifyLUNLin} {: support} 1. In the command line, run `multipath -ll` and look at the output. ```sh root@server:~# multipath -l 3600a098038303845372b4a5232346e35 dm-0 NETAPP ,LUN C-Mode size=12T features='4 queue_if_no_path pg_init_retries 50 retain_attached_hw_handle' hwhandler='1 alua' wp=rw -+- policy='round-robin 0' prio=50 status=active - `1:0:0:0 sdc 8:32 active ready running` 3600a098038304471562b4c4743384332 dm-1 NETAPP ,LUN C-Mode size=12T features='4 queue_if_no_path pg_init_retries 50 retain_attached_hw_handle' hwhandler='1 alua' wp=rw -+- policy='round-robin 0' prio=10 status=active `- 3:0:0:1 sdd 8:48 active ready running` ``` {: screen} Note "1:0:0:0" and "3:0:0:1". The last digits in each of these fields "1:0:0:0" and "3:0:0:1", the "0" and "1" are the iscsi LUN ID numbers of your block storage devices. 2. Enter the following CLI commands: `ibmcloud sl block volume-list` and `ibmcloud sl block volume-detail` to compare their outputs to the information that you collected in Step 1. ```sh $ ibmcloud sl block volume-list id username datacenter storage_type capacity_gb bytes_used lunId 20973781 IBM02SEL1575811-1 dal09 endurance_block_storage 100 - 3 22030583 IBM02SEL1575811-3 dal12 endurance_block_storage 20 - 0 23976093 IBM02SEL1575811-4 dal12 performance_block_storage 80 - 1 24024217 IBM02SEL1575811-5 seo01 performance_block_storage 2000 - 2 ``` {: screen} ```sh $ ibmcloud sl block volume-detail 22030583 Name Value ID 22030583 User name IBM02SEL1575811-3 Type endurance_block_storage Capacity (GB) 20 LUN Id 0 Endurance Tier READHEAVY_TIER Endurance Tier Per IOPS 2 Datacenter dal12 Target IP 161.26.110.17 Snapshot Size (GB) 5 Snapshot Used (Bytes) 3325952 # of Active Transactions 0 Replicant Count 0 ``` {: screen} The output shows the hostname of the storage device, the LUN ID, and the Target IP: ```sh IBM02SEL1575811-3 lun id: 0 Target IP: 161.26.110.17 IBM02SEL1575811-4 lun id: 1 Target IP: 161.26.110.43 ``` {: screen} 3. You can further confirm this information by using the following command `iscsiadm -m session -P 3`. ```sh # iscsiadm -m session -P 3 iSCSI Transport Class version 2.0-870 version 6.2.0.874-7 Target: iqn.1992-08.com.netapp:stfdal1201 (non-flash) Current Portal: 161.26.110.17:3260,1027 # match this target iscsi IP to the block storage device Persistent Portal: 161.26.110.17:3260,1027 ********** Interface: ********** Iface Name: default Iface Transport: tcp Iface Initiatorname: iqn.2018-08.com.ibm:ibm02su1575811-i117305979 Iface IPaddress: 10.74.10.67 Iface HWaddress: Iface Netdev: SID: 1 iSCSI Connection State: LOGGED IN iSCSI Session State: LOGGED_IN Internal iscsid Session State: NO CHANGE ********* Timeouts: ********* Recovery Timeout: 5 Target Reset Timeout: 30 LUN Reset Timeout: 30 Abort Timeout: 15 ***** CHAP: ***** username: IBM02SU1575811-I117305979 password: ******** username_in: password_in: ******** ************************ Negotiated iSCSI params: ************************ HeaderDigest: None DataDigest: None MaxRecvDataSegmentLength: 262144 MaxXmitDataSegmentLength: 65536 FirstBurstLength: 65536 MaxBurstLength: 65536 ImmediateData: Yes InitialR2T: No MaxOutstandingR2T: 1 ************************ Attached SCSI devices: ************************ Host Number: 1 State: running scsi1 Channel 00 Id 0 Lun: 0 # match the "Lun: 0" here to the LUN ID. Attached scsi disk sdc State: running Current Portal: 161.26.110.43:3260,1041 # match this target iscsi IP to the block storage device. Persistent Portal: 161.26.110.43:3260,1041 ********** Interface: ********** Iface Name: default Iface Transport: tcp Iface Initiatorname: iqn.2018-08.com.ibm:ibm02su1575811-i11730597 Iface IPaddress: 10.74.10.67 Iface HWaddress: Iface Netdev: SID: 3 iSCSI Connection State: LOGGED IN iSCSI Session State: LOGGED_IN Internal iscsid Session State: NO CHANGE ********* Timeouts: ********* Recovery Timeout: 5 Target Reset Timeout: 30 LUN Reset Timeout: 30 Abort Timeout: 15 ***** CHAP: ***** username: IBM02SU1575811-I117305979 password: ******** username_in: password_in: ******** ************************ Negotiated iSCSI params: ************************ HeaderDigest: None DataDigest: None MaxRecvDataSegmentLength: 262144 MaxXmitDataSegmentLength: 65536 FirstBurstLength: 65536 MaxBurstLength: 65536 ImmediateData: Yes InitialR2T: No MaxOutstandingR2T: 1 ************************ Attached SCSI devices: ************************ Host Number: 3 State: running scsi3 Channel 00 Id 0 Lun: 1 # match the "Lun: 1" here to the LUN ID. Attached scsi disk sdd State: running ``` {: screen} ## Viewing the LUN ID in Windows {: #identifyLUNWin} {: support} 1. In PowerShell, issue the command `iscsicli SessionList| findstr /c:"Device Number" /c:"Location" /c:"Target Portal"`. The output shows the IP address and the LUN ID. In the example, the IP address is 10.201.174.123 and the LUN ID is LUN 0. ```powershell C:\Users\Adminisitrator>iscsicli SessionList| findstr /c:"Device Number" /c:"Location" /c:"Target Portal" Target Portal : 10.201.174.124/3260 Device Number : 3 Location : Bus Number 0, Target Id O, LUN 0 Target Portal : 10.201.174.123/3260 Device Number : 4 Location: : Bus Number 0, Target ID 1, LUN 0 ``` {: screen} 2. Then, enter the following CLI commands: `ibmcloud sl block volume-list` and `ibmcloud sl block volume-detail` to compare their outputs to the information that you collected in Step 1. ```sh $ ibmcloud sl block volume-list id username datacenter storage_type capacity_gb bytes_used lunId 333280508 SL02SEL1160157-221 dal10 endurance_block_storage 200 - 0 333506786 SL02SEL1160157-222 tok02 endurance_block_storage 200 - 0 ``` {: screen} ```sh $ ibmcloud sl block volume-detail 333506786 Name Value ID 333506786 User name SL02SEL1160157-222 Type endurance_block_storage Capacity (GB) 200 LUN Id 0 Endurance Tier READHEAVY_TIER Endurance Tier Per IOPS 2 Datacenter tok02 Target IP 10.201.174.123 # of Active Transactions 0 Replicant Count 0 ``` {: screen} ## Viewing the LUN ID in VMWare® {: #identifyLUNVMware} {: support} 1. Run the `esxcli storage vmfs extent list` command. The output includes the volume name `iscsi-datastore` and its unique Network Addressing Authority (`naa`) identifier. That number is guaranteed to be unique to that LUN. ```sh Volume Name VMFS UUID Extent Device Name Partition Number --------------- ----------------------------------- ------ ------------------------------------ ---- datastore1 5f69774e-f1031e44-7bdb-ac1f6bc4b812 0 naa.600062b2049d040026fc1e4b2f305682 3 iscsi-datastore 621f425f-0dc2da8a-927b-ac1f6bc4b812 0 naa.600a098038305674695d51694b427849 1 ``` {: screen} 2. Next, enter the `esxcfg-mpath -b` command. The output contains the same `naa` number, the LUN ID, and the PortalTag. ```sh naa.600a098038305674695d51694b427849 : NETAPP iSCSI Disk (naa.600a098038305674695d51694b427849) vmhba64:C0:T1:L0 LUN:0 state:active iscsi Adapter: iqn.2020-10.com.ibm:sl02su1160157-h1907004 Target: IQN=iqn.1992-08.com.netapp:stfdal1007 Alias= Session=00023d000001 PortalTag=1034 vmhba64:C1:T1:L0 LUN:0 state:active iscsi Adapter: iqn.2020-10.com.ibm:sl02su1160157-h1907004 Target: IQN=iqn.1992-08.com.netapp:stfdal1007 Alias= Session=00023d000002 PortalTag=1030 ``` {: screen} In the example, the string `LUN:0` means that the LUN ID is 0. 3. Issue the `esxcli iscsi adapter target portal list` command. From the output, note the IP address and Tpgt value that matches the Portal Tag. ```sh Adapter Target IP Port Tpgt ------- --------------------------------- ------------- ---- ---- vmhba64 iqn.1992-08.com.netapp:stfdal1007 161.26.99.155 3260 1034 vmhba64 iqn.1992-08.com.netapp:stfdal1007 161.26.99.152 3260 1030 ``` {: screen} In the example, the IP address "161.26.99.155" is the target IP address of your Block Storage for Classic and "1034" is the PortalTag. 4. Next, use the IBMCLOUD CLI command `ibmcloud sl block volume-list`. The output contains the volume ID, the hostname of the storage device, the DC location, storage type, capacity, the amount of space that is already used, and the LUN ID. ```sh $ ibmcloud sl block volume-list id username datacenter storage_type capacity_gb bytes_used lunId 221426384 SL02SEL1160157-195 che01 endurance_block_storage 1500 - 2 332299016 SL02SEL1160157-220 dal13 endurance_block_storage 20 - 2 333280508 SL02SEL1160157-221 dal10 endurance_block_storage 200 - 0 ``` {: screen} In the example, the string "333280508" is the volume ID and "0" is the LUN ID of your Block Storage for Classic LUN. Issue the command `ibmcloud sl block volume-detail` to get more detailed information about the storage volume. ```sh $ ibmcloud sl block volume-detail 333280508 Name Value ID 333280508 User name SL02SEL1160157-221 Type endurance_block_storage Capacity (GB) 200 LUN Id 0 Endurance Tier READHEAVY_TIER Endurance Tier Per IOPS 2 Datacenter dal10 Target IP 161.26.99.155 # of Active Transactions 0 Replicant Count 0 ``` {: screen} So you can map the iscsi LUN ID to the block device's hostname: ```sh SL02SEL1160157-221 lun id: 0 Target IP: 161.26.99.155 ``` {: screen} ## Viewing the LUN ID in the console {: #identifyLUNUI} {: support} You can also gather the LUN ID, Target IP address, and hostname of the Block Storage for Classic device on the Volume Details page in the console. ![The Volume Details page in the console provides detailed information about the LUN. The storage volume name is shown with the Name label. The target IP address is labeled as Target address. The LUN ID is shown as Volume ID.](images/vmwareLUNID.svg "Block Storage Volume Details in the Console."){: caption="The Volume Details page of the console provides detailed information about the LUN." caption-side="bottom"}