Overview of the iSCSI protocol for VMware

1. iSCSI for Better
or Worse
STEVEN AIELLO

2. “Love me or hate me, both are
in my favor…
If you love me, I'll always be in
your heart…If you hate me, I'll
always be in your mind.”
~ William Shakespeare

3. Who Am I?
 Steven Aiello
 CISSP, CISA, VCP 5, CCNA (long ago)&
some other crappy ones…
 MSP Online Tech
 ADP Sorry if you work there = (
 Focus One Data

4. What’s My Background?
 Focus One: Primarily focused on health care data.
HIPAA was new (2002-2004)…
 ADP: Large scale data center deployments
 Online Tech: Lead VMware Eng.
 Almost 40 ESXi hosts
 Veeam (360 VMs)
 VMware SDK C#
 Datacenter migration avg. 3.5 min of down time
per server

5. Block vs. File
Sorry Internet police I stole this image = (

6. FC, iSCSI, & NFS
 Fibre Channel provided the highest throughput and the lowest processor
utilization of all the storage protocols.
 Software iSCSI provided only slightly lower throughput than Fibre
Channel (not more than 9% or 10% less than Fibre Channel depending
upon the specific tests being run). However, software iSCSI consistently
showed the highest CPU utilization on the ESX hosts.
 NFS showed throughput on the same levels as software iSCSI (again, not
more than about 9% or 10% less than Fibre Channel depending upon the
tests being run) and had higher CPU utilization than Fibre Channel.
However, the CPU utilization was lower than with software iSCSI.
 Source: NetApp

7. FC, iSCSI, & NFS
Why?

8. What is iSCSI
1. Block level storage
2. SCSI Commands
3. Encapsulate into an IP packet
4. Send it over Ethernet
5. Picked up by the controller
6. Reverses the encapsulation process
7. iSCSI Bi-Directional

9. iSCSI ~ RFC 3720
 I would recommend you read this…
 iSCSI consists of
 Initiator (the client)
 Target (the server)
 IQN:
A date code, in yyyy-mm format. This date MUST be a date during which
the naming authority owned the domain name used in this format, and
SHOULD be the first month in which the domain name was owned by this
naming authority

10. IQN Format

11. iSCSI Considerations
 Dedicated network
 Network Design
(“Don’t let your network guys screw with your storage network…”)
 MTU (1500 MTU or 9000 MTU?)
 Switch buffer sizes

12. iSCSI Gossip
 Intel NICs
 DELL partner
 Expressed discontent with Broadcom drivers
 Expressed discontent with DELL switches
 Cisco seemed to be the preferred brand

13. Why Use iSCSI?
 Raw Device Mappings
 Windows Server Clustering
(may not be needed in the future)
 SAN management Software
 Easier multi-pathing
 iSCSI connections from your hosts

14. Why Use NFS?
 You don’t wont to screw with iSCSI…
 Larger datastores without extents
 You have the resources to install 10Gb
Ethernet
 More flexible storage system, expand the size
of your data stores
 You don’t have a need for:
 RDMs
 Direct SAN access for your applications

15. Switch Port Security… (fail)
Look for cut off iSCSI messages in the vmkernel log…

16. LUN Security & Access
 iSCSI Access Controls
 CHAP (UN & PW)
 IP Address or Subnet Block (Not my fav.)
 IQN (Think of MAC address filtering)

17. iSCSI Multi-Pathing
 Most Recently Used
 Round Robin (make sure your storage device
supports this)
 Fixed

18. iSCSI Multi-Pathing = (
FML…

19. iSCSI Multi-Pathing = (

20. iSCSI Multi-Pathing = (
 MS KB: 2522766
 20 Years of banking data
 Random and excessive NTFS errors
 A week of sleepless nights…

21. Third Party Integration
 Kudos to Equallogic on their HIT kit
 MEM
 Better multi-pathing
 SAN based snapshots using VSS

27. Wrap Up – Why Use It?
 Raw Device Mappings
 Windows Server Clustering
(may not be needed in the future)
 SAN management Software
 Easier multi-pathing
 iSCSI connections from your hosts

28. Wrap Up – Why Use NFS?
 You don’t wont to screw with iSCSI…
 Larger data stores without extents
 You have the resources to install 10Gb
Ethernet
 More flexible storage system, expand the size
of your data stores
 You don’t have a need for:
 RDMs
 Direct SAN access for your applications

29. Questions?
Steven Aiello
saiello@onlinetech.com
steven@overworkedadmin.com