Powered by System Center
Posts tagged iSCSI
Sharing an iSCSI network between the host and a guest
Jul 18th
At one of our customers site we’ve deployed a Hyper-V cluster (HP Proliant BL460c G7 servers) with two HP (LeftHand) P4000 SAN systems (spread over two locations). We’re using iSCSI for SAN connections. Network adapters are configured through HP VirtualConnect. Each server has 8 NICs (4 from LOM1 and 4 from LOM2):
- 2 adapters in a team for the parent partition
- 2 adapters in a team for the CSV nework
- 2 adapters in a team for the virtual machine network
- 2 adapters for iSCSI connections (teamed through MPIO)
Carsten Rachfahl interviews Hans Vredevoort on Hyper-V and stuff
May 5th
Last week @hypervserver (Carsten Rachfahl) visited me for an interview about topics around Microsoft Virtualization, the Hyper-V community, Hyper-V & System Center (Virtual Machine Manager 2012), Microsoft Software iSCSI target and the choice between Fibre Channel and iSCSI.
Carsten regularly interviews people in the IT industry, but this time it was his first time in English. Although a bit uneasy at first, he did a wonderful job and I never misunderstood his questions.
Before we realized it we had talked for 40 minutes without a break. Although I didn’t know what he was going to ask, they were all well within my field of competence.
Normally I always find it difficult to hear your own voice and see yourself on video. But when I finally convinced my self I had to watch it at least once, I must say I am quite pleased with the result. So here you have a chance of getting to know me a little better and hear about the things I am working on.
I’d like to thank Carsten for a very pleasant and positive experience!
UPDATED: Supported and tested Microsoft iSCSI Software Target 3.3 limits
Apr 11th
This post is updated after co-blogger Hans Vredevoort contacted some of the storage folks in Microsoft to discuss the MPIO/cluster member initiators issue. It turns out that order list number 3 is not correct.
As a follow-up after releasing the Microsoft iSCSI Software Target 3.3 Microsoft has released an support article specifing the limits.
Supported and tested Microsoft iSCSI Software Target 3.3 limits
This topic provides the supported and tested Microsoft iSCSI Software Target 3.3
limits. The following tables display the tested limits and the enforced limits
where applicable.In addition, the following limits apply:
- You should not use network adapter teaming with Microsoft iSCSI Software
Target 3.3 for iSCSI communication. - If you plan to use multiple network adapters for iSCSI communication, you
should separate them into their own subnets, set up virtual IP addresses, and
then implement MPIO. - MPIO is
notsupported for iSCSI initiators when used in conjunction with
Microsoft iSCSI Software Target if the initiators are part of a failover
cluster.
Aidan Finn has written a white paper about using Microsoft iSCSI Software Target 3.3 and also posted a blog about the confusion created by KB2535811.
iSCSI Target in Windows Server 2008 R2
Apr 4th
A couple of years ago Microsoft acquired a company called “String Bean Software” which was IMHO a simple but great iSCSI Target solution, and it it was incorporated into the StorageServer product.
Today Microsoft launched the iSCSI Software target 3.3 for public download. This is absolutely great, now we have the possibility to create (Hyper-V) clusters on shared storage!
More info on the Jose Barrato’s Blog and it can be downloaded from the Microsoft download site: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=45105d7f-8c6c-4666-a305-c8189062a0d0

Array firmware as a limiting factor in R2 clusters
Jan 7th
It is not uncommon that hardware vendors have to fix their array controller firmware. In this case it is HP’s P2000 G3 firmware for the FC/iSCSI combined models. Again it is a fix for problems as a result of customers using bigger clusters. Here we have a problem with Windows Server 2008 R2 clusters which surfaces with bigger clusters, long IQN names and a maximum of the space available for SCSI-3 reservations. Haven’t we seen this kind of trouble before. I can assure you that admins of Hyper-V R2 clusters surpassing these limits weren’t all that happy.
Issue:
Using a long IQN name for iSCSI initiators may lead to issues while using SCSI-3 reservations and Persistent Group Reservations, particularly when trying to create large clusters with multiple paths to each LUN. A predefined area is used to store SCSI-3 reservation keys for each initiator path to each LUN and, when a large number of IQN entries are attempted to be stored, the array can run out of space in this area. This issue is dependent on the number of nodes and the number of paths per node accessing individual LUNs. This issue has been seen during the cluster validation process on Windows 2008 R2 clusters with 16 nodes, where each node had 4 paths to each LUN of the array.
Large clusters with HP P4000 and many iSCSI sessions
Jan 5th
In October 2010 HP published a customer advisory, warning for cluster resource failures in large Microsoft Windows 2008 and R2 clusters using multiple host NICs with HP P4000 SAN and its Device Specific Module (DSM) for MPIO.
If any combination of cluster nodes, MPIO NIC ports and storage nodes resulted in more than 31 iSCSI sessions per volume, these issues would surface. Cluster Validation tests would in fact fail in these configurations. Adding a cluster node or storage node without validation would fail or only partly work.
HP published a firmware update with patch 10085-00 increasing the number of iSCSI sessions from 31 to 64. HP promised to solve this problem in its next major release of P4000 SAN/iQ software.
The formula for calculating the number of iSCSI sessions is:
# of Microsoft cluster nodes *
( # of initiator NICs per cluster node * # of storage nodes)
Now that SAN/iQ 9.0 has been released we can see that HP has followed up on this issue:
A HP Support document released in December 2010 states that with the new release, it has solved problems with SCSI Persistent Group Reservation (PGR) by increasing the limit to 256 iSCSI sessions per volume. This number is high enough to cope with 16 cluster nodes and 8 storage nodes with two iSCSI network adapters. This adds up to 16 x 2 x 8 = 256: so still be careful with bigger configurations.
Performance characterization report for Microsoft Hyper-V R2 on HP StorageWorks P4500 SAN storage
Jul 18th
HP has published a technical whitepaper focusing on the performance characterization of the disk sub-system for HP StorageWorks P4500 21.6TB SAS Multi-site SAN Solution (HP P4500 SAN), addressing questions a customer may have about deploying Microsoft’s Hyper-V R2 virtual machines (VMs) on HP ProLiant BL490c G6 Virtualization Blades (ProLiant BL490c G6) with HP P4500 iSCSI SAN storage device for backend storage.
Target audience: The intended audience includes, but is not limited to, individuals or companies who are interested in the use of Hyper-V R2 virtualization technology for consolidation and migration of servers to ProLiant BL490c G6 servers with HP P4500 SAN storage solutions.
This white paper describes testing performed in April 2010:
http://h20195.www2.hp.com/V2/GetPDF.aspx/4AA1-9557ENW.pdf
A Hyper-V update rollup package is available for Windows Server 2008 R2
Nov 25th
Several issues around VSS based protection & recovery are being addressed with this Hyper-V update rollup package. The package can be downloaded from:
http://support.microsoft.com/hotfix/KBHotfix.aspx?kbnum=975354&kbln=en-us
The last three issues might sound familiar if you already perform host level protection of virtual machines on Cluster Shared Volumes (CSV) with Microsoft System Center Data Protection Manager 2010.
Issues that are fixed in this update rollup package
Issue 1
Consider the following scenario:
- Some Internet SCSI (iSCSI) connections are created in a virtual machine that is running Windows Server 2003.
- You back up this virtual machine on the virtual machine host server.
In this scenario, the error code 0x800423f4 occurs when you back up the virtual machine. Additionally, the following event is logged into the Hyper-V Virtual Machine Management Service event log:
The number of reverted volumes does not match the number of volumes in the snapshot set for virtual machine "’virtual machine name’ (Virtual machine ID <GUID>)".
Cause of Issue 1
When a virtual machine is being backed up, the VSS writer of the server that is running Hyper-V makes a call to the guest virtual machine to check whether any iSCSI connections exists. This call has a default time-out of 60 seconds. If this call does not return within the time limitation, the VSS writer of the server that is running Hyper-V incorrectly assumes that there is no iSCSI connection. Therefore, the backup operation fails.
Issue 2
Consider the following scenario:
- Cluster shared volumes are enabled on a failover cluster for Hyper-V.
- Some virtual machines are saved on the same volume. But they are running on different nodes.
- These virtual machines are backed up in parallel.
In this scenario, the virtual machine backup operation fails.
Cause of Issue 2
When the virtual machines on different nodes are backed up in parallel, every node waits to become the cluster shared volume owner to create the snapshots. However, the Cluster service moves the volume owner from one node to another node immediately after a snapshot is created without waiting for post-snapshot tasks to be completed. If another node requests the same shared volume for a backup operation before the post-snapshot tasks are completed, the Cluster service changes the volume to another node. Therefore, the VSS writer that is in the previous node cannot find the cluster shared volume locally when it performs post-snapshot tasks. This behavior causes the virtual machine backup operation to fail.
Issue 3
Consider the following scenario:
- A virtual machine is being backed up on a server that is running Hyper-V.
- At the same time, an application backup operation is being performed in the same virtual machine.
In this scenario, some data is truncated from the application backup in the virtual machine. Therefore, this behavior causes data loss.
Cause of Issue 3
The application backup operation in the virtual machine is incorrectly affected by the virtual machine backup operation on the server that is running Hyper-V.
Issue 4
Consider the following scenario:
- A virtual machine that has some snapshots is backed up on a server that is running Hyper-V.
- Then, this virtual machine is restored to another location.
In this scenario, the restore operation fails and the virtual machine may be corrupted.
Cause of Issue 4
The snapshot files are not restored successfully when you restore the virtual machine.
Full details: http://support.microsoft.com/kb/975354
Best Practices to Implement Windows Server 2008 R2 and Hyper-V R2 on HP ProLiant Servers (Part 2)
Nov 15th
On the first day of TechEd Europe 2009, Doug Dewerd presented a session on best practices to implement Windows Server 2008 R2 on HP ProLiant Servers. This is in fact the combination of hardware and software I have preferred ever since Windows and ProLiant were joined, exactly 20 years ago last week. The ProLiant server was produced by Compaq and replaced the first PC based server, the Compaq SystemPro which was released in 1989. A nice best practice not many customers are aware of is that ever since the first ProLiant model, the Smart Array Controllers have shared a common driver family. Standardization even on the driver level has worked well for many of our clients. You probably have seen several vendors who introduced new technology, but have switched the configuration software and driver installation methodology quite a bit.
On the agenda were four topics:
-
HP Servers and Windows Server 2008 R2
-
HP and Hyper-V R2
-
HP Management Tools
-
HP Storage Support
HP Servers and Windows Server 2008 R2
HP ProLiant Servers combined with R2 mean a considerable reduction in power consumption and improved consolidation ratio’s. The HP ProLiant G6 servers use half the power of previous generations of servers, support more processors and are certified with R2 advanced power management. Especially combined with HP Virtual Connect Flex-10 technology virtualization ratio’s can be improved significantly at a lower price level than traditional switches in a blade enclosure. Furthermore a deep integration with Microsoft System Center improves availability and simplifies management.
There are three interesting things that help efficiency in the datacenter:
-
HP LeftHand SAN products which provide high availability without the requirement to buy additional synchronous replication software. This iSCSI based storage is fully transparent to Hyper-V R2 and Cluster Shared Volumes and Live Migration. LeftHand superbly mirrors data blocks (Network RAID) across storage nodes and by simply spreading the nodes of the storage cluster across sites, a fully automated and disaster tolerant solution can be built. Of course the network interconnects have to be superb as well for synchronous replication to be efficient, although asynchronous replication is also supported out of the box.
-
EVA CLX (Cluster Extensions) now supports Live Migration and disaster recovery. This software, not being the cheapest around, is able to eliminate service disruption and automatically fails over or back with Microsoft failover cluster services when disaster strikes.
-
An integration is made available between the HP Configuration & Sizing Tool for Hyper-V and MAP (Microsoft Assessment & Planning) tool. It can build detailed HP configurations for R2, Hyper-V and applications.
If you want to find out which HP ProLiant Servers are supported for Windows Server 2008 R2 and Hyper-V R2, just go to:
http://h71028.www7.hp.com/enterprise/us/en/servers/ws-servers-2008-r2.html
HP fully supports Windows Server 2008 R2 and Hyper-V R2 for both it’s fifth and sixth generation of tower, rack and blade servers with one or two exceptions. Just check the support matrix.
Power Control with Windows Server 2008 R2
Windows Server 2008 R2 has done great things for intelligent support for power control. R2 supports the new processor performance state interface which enables OS and platform coordination of processor power management:
-
Platform is in direct control of t- and p-states
-
OS specifies processor performance requirements
-
Platform is responsible for delivering requested performance
-
Interface is described via ACPI which is jointly developed by HP and Microsoft
The collaborative power controls are available in ProLiant G6 servers and blade and combine the OS independent HP Power Regulator and Windows Server 2008 R2’s Power Metering & Budgeting infrastructure. PMB manages power based on its knowledge of incoming work queues and task scheduling, whilst HP Power Regulator manages power based on the state of the hardware and the reaction speed necessary to protect hardware.
The process is like this:
-
Windows asks for what it thinks is best
-
The hardware grants that request unless it can’t because of hardware constraints
-
Then the hardware tells the OS what it actually got
This joint effort at improving Green IT can reduce energy cost by as much as 70%.
Scalability and Performance
Windows Server 2008 R2 improves on physical processor and memory resources, running exclusively on 64-bit processors, it supports up to a maximum of 256 processors. R2 also improves on virtual processor resources. Hyper-V R2 now supports up to 64 logical processors (cores or hyper-threaded CPU’s). Accepting processor overcommit, Hyper-V R2 allows for 512 virtual CPU’s per physical host. The current limit of vCPU’s per virtual machine is 4.
An extremely important improvement is the support for SLAT (Second Level Address Translation) which reduces hypervisor processor time and saves about 1MB of memory per virtual machine by using processor functionality to carry out virtual machine memory management functions. In short, memory management is delegated to the processor with better scalability and performance as the result.
Doug showed an example of near linear scalability in throughput with no virtual CPU overcommit (n
o more vCPU’s are used than the amount of physical CPU’s available).
These are the graphs you want to see that could make you wonder why you wouldn’t virtualize even your heavier database servers. In fact we only need to get more experience and faith in hypervisors like Hyper-V R2.
A helpful site with technical guidance, reference configurations, performance characterization and test results, white papers, tools, system configurators, capacity planners and sizers can be found on HP ActiveAnswers.
Hyper-V Support
Most ProLiant servers support Hyper-V R2. At a minimum HP ProLiant Support Pack (PSP) 8.30 must be used. Be careful to install PSP before enabling the Hyper-V role and don’t install PSP on the guests. Furthermore, check the HP whitepapers on Hyper-V R2 integration for the minimum ROM version, supported options and NIC Teaming information.
Hyper-V R2 Installation Tips
-
Check HP R2 white paper to ensure servers, options and storage are supported
-
Update server BIOS if needed
-
Enable support for No-Execute and hardware-assisted virtualization in RBSU (Rom Based Server Utility)
-
Install OS, then ProLiant Support Pack without Network Configuration Utility (NCU), then enable Hyper-V
-
-
If installing HP Systems Insight Manager or HP Insight Control for System Center, make sure that SNMP is configured and started
-
-
-
NIC Teaming is supported provided that
-
-
The latest version of Hyper-V is installed and enabled
-
HP ProLiant Network Teaming Software is installed and enabled after having enabled Hyper-V
-
-
Hyper-V Server R2 or Server Core with Hyper-V R2 Installation
-
Copy PSP executables to subdirectory and extract
-
If installing HP SIM or HP Insight Control for System Center, make sure SNMP service has started
-
-
Run oclist.exe to list the services that have started
-
If SNMP has not started, execute the command start /w ocsetup SNMP-SC to start the SNMP service
-
-
-
Run setup.exe from folder
-
Select Bundle Filter and options
-
Select items to be installed
-
View Installation Results upon completion
NIC Teaming Notes
- Use HP Networking Configuration Utility (NCU) version 9.35 or greater
- VLAN procedure
-
- Install and enable Hyper-V, and then install the NCU
- Configure the NIC team(s)
- Configure VLANs for the team(s)
-
- IMPORTANT – There is currently no way to easily uninstall HP NCU from Server Core installs
-
- Can cause a problem when trying to perform Hyper-V updates
- Perform manual uninstall of HP NCU following http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01663264/c01663264.pdf and http://support.microsoft.com/kb/950792/en-us
- HP will release a fix in a future version of NCU
-
Known Hyper-V R2 Issues
- Stop 0x0000007E blue screen displays after initial reboot when Hyper-V is installed on Windows Server 2008 R2
-
- Microsoft has published a KB Article and a Hot Fix to prevent the issue from occurring at http://support.microsoft.com/kb/974598
-
- After enabling the Hyper-V server role on an HP ProLiant DL785 G5 Server, a black screen displays after the system reboots
-
- Upgrade the ProLiant DL785 G5 server to version A15 of the System ROM dated 08/14/2009 (or later).
-
- The virtual machine network is not working when the external virtual network is connected to 1-Gbps NC375i NIC on an HP ProLiant ML370 G6 Server
-
- This issue has been reported to HP and is being worked
- The network driver will be released to the support and drivers page after the issue is resolved
-
Networking Challenges
- The total network throughput requirement on Hyper-V host is significantly higher than on traditional servers
- Consolidated servers may not have same requirements
-
- Access to different VLAN’s
- Access to additional bandwidth
-
- Varying requirements lead to additional complexities
-
- Increased number of uplinks
- Increased number of ports
- Increased number of cables
-
If you add up all the NICs that are required for all the networks with full redundancy in an ideal configuration, you end up with staggering numbers.
In fact this could be downsized a little in my opinion. Let’s say you use fibre channel SAN and a Hyper-V R2 cluster with Live Migration, I would normally advise:
| Network | Minimum | Sufficient |
| Domain Access + Management + HB | 2 | 2 |
| Live Migration + CSV + HB | 2 | 2 |
| Production VM’s | 2 | 4 |
| Total | 6 | 8 |
In previous Windows failover clusters there was a requirement for a Cluster Heartbeat (HB) or Private Network. In Windows Server 2008 Failover Clusters, an alternative path is recommended so if one NIC goes down, another NIC is used to check the cluster heartbeat. In our example the first two networks can serve this purpose. Since Windows Server 2008 the heartbeat/cluster NIC is supported in a NIC Teaming configuration.
For production VM’s at least two teamed NIC’s can be used with at least 2 x 1GB speed. Maybe even 4 x 1GB speed to allow for more network throughput. If 8 NICs are used we end up with eight Gigabit switches in a typical HP c-Class 7000 blade enclosure. Counting these switches including, cabling and core Ethernet switch ports plus tedious management, this can easily become a very expensive solution. For this reason HP has developed HP Virtual Connect Flex-10 Interconnects. With only two of these modules, each BL ProLiant BL G6 and higher server can be configured to split the two 10Gb Ethernet ports into 8 so called FlexNICs which are not virtual but fully functional hardware based Ethernet NICS. The speed of these FlexNICs can be set to any speed between 100MB and 10Gb Ethernet.
With Flex-10 the table looks like this:
| Network | FlexNICs | Gbps |
| Domain Access + Management + HB | 2 | 2 |
| Live Migration + CSV + HB | 2 | 4 |
| Production VM’s | 2 | 8 |
| or devote some FlexNICs to iSCSI | 2 | |
| Total | 8 | 20 |
If more is required in the future with even higher densities of cores, memory and consequently VM’s, we can add up to six HP VC Flex-10 Interconnect modules with the total capacity of 24 NICs per server blade. Who said blade servers are not scalable? Unfortunately I cannot tell you what HP showed us in the NDA room, but servers are surely bound to become bigger and much more scalable. Sorry, you have to wait until some time next year. But rest assured that the current HP ProLiant G6 family is very scalable and even half-height blades can handle up to 24 cores, 192GB of memory and 4 x 10Gb of network capability (if you include an extra dual-port 10Gb Ethernet mezzanine module. Of course scalability will improve further in the next year. And you can grow with it, while keeping the server blade infrastructure in place.
HP Insight Portfolio
HP offers several management products for its ProLiant servers: HP Insight Foundation (included), HP Insight Control and HP Insight Dynamics.
The best news for HP and Hyper-V users is the tight integration of HP Insight software with Microsoft System Center:
-
Provides seamless integration of the unique ProLiant and BladeSystem manageability features for customers who have standardized on System Center management platforms
-
Delivered as part of HP Insight Control 6.0
-
-
In addition to the full Insight Control capabilities, it provides a set of extensions to Microsoft System Center
-
Requires one Insight Control license per managed (Hyper-V R2) server
-
-
Integration Components
-
HP Insight Control for System Center software CD components
-
-
HP ProLiant Server Management Packs for Operations Manager 2007
-
HP BladeSystem Management Pack for Operations Manager 2007
-
HP ProLiant PRO Management Pack for Virtual Machine Manager 2008 (R2?)
-
HP ProLiant Server OS Deployment for Configuration Manager 2007
-
HP Hardware Inventory Tool for Configuration Manager 2007
-
-
-
HP Catalog for System Center Configuration Manager is downloaded from the HP web
-
-
No HP Catalog software is included on the CD
-
HP Catalog support included with standard Technical Support and Software Update service
-
-
Storage Support for Hyper-V R2
Check the support matrix for HP storage and Hyper-V R2. The tables show extensive support for the current Microsoft hypervisor. In addition to this also check the Single Point of Connectivity Knowledge (SPOCK) website. You have to create or use an HP Passport for access.
One of the first storage products that fully support Hyper-V R2, Cluster Shared Volumes and Hyper-V R2 is HP LeftHand P4000 SAN Solution. Notably the Network RAID and replication capability (included in the price) is responsible for the transparency for the Hyper-V R2 cluster. A multi-site cluster of course requires a good design and proper network setup, but HP LeftHand takes a lot of complexity out of multi-site clustering.
With storage that is optimized for Hyper-V virtualization and Live Migration, virtual machines can be moved live without downtime for users. Users will not notice that both the server and the storage is moved to another datacenter. When a datacenter breaks down or blows up, virtual machines will take over in a very short amount of time (minutes), comparable to a server crash. The virtual machine is restarted quickly and users can continue their work as if nothing had happened.
Other possibilities:
- Zero Downtime Array Load Balancing
-
- IOPS
- cache utilization
- power consumption
-
- Zero Downtime Maintenance
-
- Firmware
- HBA
- Server updates without user interruption
-
- Follow the sun/moon data center access model
-
- Move the app/VM closest to the users or closest to the cheapest power source
-
- Failover, failback, Quick and Live Migration using the same management software
-
- No need to learn x different tools and their limitations
-
HP also showed us an update to HP Cluster Extensions (CLX) for Hyper-V R2 and Live Migration. This solution is intended for HP EVA and HP XP Storage Arrays with multiple sites and synchronous replication (Continuous Access). Because of the architecture of HP Continuous Access it currently cannot use Cluster Shared Volumes (CSV), which is not a problem because Live Migration does formally not depend on CSV. HP CLX therefore uses traditional shared LUNS per VM. In the demo we saw only a few pings lost during a Live Migration of both virtual machine and storage. No packet had to be retransmitted and users would not be aware of the datacenter move.
From this presentation by Doug Dewerd and Matthias Popp, I got the impression that HP takes Microsoft and Hyper-V very seriously. They have worked together for many years in the Microsoft/HP Frontline Partnership which has now culminated into fascinating products which work really well together.
With the recently formed vBlock called VCE (VMware, Cisco and EMC), I contend that HP is sort of forming an opposing block. I propose calling them MCH (Microsoft, Citrix and HP).
In fact this combination of best of breed server, storage and virtualization solutions happens to be my primary job: designing and architecting fast, flexible, highly available and highly scalable infrastructures. I got a feeling …
For Hyper-V R2 and HP Full Featured DSM / MPIO also see:
http://hyper-v.nu/blogs/hans/?p=292








Twitter
RSS