Unable to access shared Iscsi datastore from Esxi Host

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms : 

• Upon navigating to the affected ESXi host, the datastore appears as Inaccessible in the vSphere client.
• Performing a storage rescan does not help in rediscovering the missing datastore.
• Running the following command does not display details for the affected datastore:
  esxcli storage core device list -d naa id 

Environment

VMware vSphere ESXi 6.x
VMware vSphere ESXi 7.x
VMware vSphere ESXi 8.x

Cause

The iSCSI targets are not reachable through the port-bound VMKs configured on a different subnet (e.g., 10.##.##.10). However, the targets are accessible via VMKs that are on the same subnet as the storage targets (e.g., 10.##.##.20)."

Cause validation:

• Ping from port bounded VMKs to target iscsi server will fail with 100% packet loss.
  
  vmkping -I vmkx -d -s  1472 <IP address of target datastore>"
PING ##.##.###.## (##.##.###.##): 1472 data bytes

---  ##.##.###.## ping statistics ---
3 packets transmitted, 0 packets received, 100% packet loss


• In var/run/log/syslog.log file, similar entries are seen:
  

  2025-06-10T09:53:42.391Z iscsid[2098197]: session login failed with error 4,retryCount=0
2025-06-10T09:53:42.391Z iscsid[2098197]: Login Target Failed:  iqn.####-##.com.synology:######-###.Target-1.########### if=iscsi_vmk@vmk4 addr=##.#.#.###:3260 (TPGT:1 ISID:0x1) err=4
2025-06-10T09:53:42.391Z iscsid[2098197]: Login Failed: iqn.####-##.com.#####:######-###.Target-1.########### if=iscsi_vmk@vmk4 addr=##.#.#.###:3260 (TPGT:1 ISID:0x1) Reason: 00040000 Initiator Error: (0x0004 Connection failure.)
2025-06-10T09:53:42.391Z iscsid[2098197]: Login Target: iqn.####-##.com.#####:######--###.Target-1.###########if=iscsi_vmk@vmk3 addr=##.#.#.###:3260 (TPGT:1 ISID:0x2)
2025-06-10T09:53:42.392Z iscsid[2098197]: Notice: Assigned (H64 T0 C0 session=82, target=1/1)
2025-06-10T09:53:42.392Z iscsid[2098197]: cannot make a connection to ##.#.#.###:3260 (101,Network is unreachable)
2025-06-10T09:53:42.392Z iscsid[2098197]: Notice: Reclaimed Channel (H64 T0 C0 oid=1)
2025-06-10T09:53:42.392Z iscsid[2098197]: Notice: Reclaimed Target (H64 T0 oid=1)
2025-06-10T09:53:42.392Z iscsid[2098197]: session login failed with error 4,retryCount=0
2025-06-10T09:53:42.392Z iscsid[2098197]: Login Target Failed:  iqn.####-##.com.synology:######-###.Target-1.###########if=iscsi_vmk@vmk3 addr=##.#.#.###:3260 (TPGT:1 ISID:0x2) err=4
2025-06-10T09:53:42.392Z iscsid[2098197]: Login Failed: iqn.####-##.com.######:######--###.Target-1.###########if=iscsi_vmk@vmk3 addr=##.#.#.###:3260 (TPGT:1 ISID:0x2) Reason: 00040000 Initiator Error: (0x0004 Connection failure.)
2025-06-10T09:53:42.395Z iscsid[2098197]: Login Target: iqn.2015-11.com.hpe:storage.########.########### if=iscsi_vmk@vmk4 addr=##.#.#.###:3260 (TPGT:1 ISID:0x1)
2025-06-10T09:53:42.395Z iscsid[2098197]: Notice: Assigned (H64 T1 C0 session=83, target=2/2)
2025-06-10T09:53:42.395Z iscsid[2098197]: cannot make a connection to ###.#.#.10:3260 (112,Host is down)

  2025-06-10T08:20:49.893Z iscsid[2098197]: Notice: Reclaimed Channel (H64 T1 C0 oid=3)
2025-06-10T08:20:49.893Z iscsid[2098197]: Notice: Reclaimed Target (H64 T1 oid=3)
2025-06-10T08:20:49.893Z iscsid[2098197]: session login failed with error 4,retryCount=0
2025-06-10T08:20:49.893Z iscsid[2098197]: Login Target Failed: iqn.####-##.com.######--###.Target-11.############ if=iscsi_vmk@vmk4 addr=##.#.#.###:3260(TPGT:65536 ISID:0x1) err=4
2025-06-10T08:20:49.893Z iscsid[2098197]: Login Failed: iqn.####-##.com.######:######--###.Target-11.########### if=iscsi_vmk@vmk4 addr=##.#.#.###:3260 (TPGT:65536 ISID:0x1) Reason: 00040000 Initiator Error: (0x0004 Connection failure.)
2025-06-10T08:20:49.893Z iscsid[2098197]: Login Target: iqn.####-##.com.:######--###.Target-11.########### if=iscsi_vmk@vmk3 addr=##.#.#.###:3260 (TPGT:65536 ISID:0x2)

 

Resolution

 

• Engage Network team to configure port binding as per supported recommendation.
  • Refer KB for Considerations for using software iSCSI port binding in ESXi.