How to take process dump using CDB

Just a short explanation of how to take process dump using CDB.

First you need to get Debugging Tools for Windows. To get Debugging Tools as a standalone tool set you can just download Windows SDK and during installation select Debugging Tools for Windows:

Installing Debugging Tools for Windows

Once Debugging tools for Windows are downloaded and installed you can find cdb.exe in the following location – C:\Program Files (x86)\Windows Kits\10\Debuggers\x64 (note that number highlighted in bold may vary depending on SDK version installed – in my case it is 10, and you obviously have cdb.exe for different platforms – x86/x64 etc. – just navigate to appropriate subfolder of Debuggers folder).

To take dump launch CMD in elevated mode, switch directory to CDB location and execute cdb -p <PROCESS PID> to take crash dump (remember that PID information can be found in Task Manager or retrieved with PowerShell using Get-Process “%ProcessName%” | select -expand id):

CDB attaching to the process by PID

At this stage CDB is attached to process and closing this CMD window will terminate process you are attached to. Once CDB is loaded type in the following commands:

..loadby sos clr


You will receive “No export Thread found” error – it can be ignored, and some more commands needs to be executed. First run !StopOnException -create System.StackOverflowException it may not work from the first attempt, just re-run it once again until you see confirmation that breakpoint was created:

CDB set breakpoint

Once breakpoint is set type gn and wait for process crash:

When process crashed the following commands have to be executed:

.logopen C:\dumps\k2hostserver.log



.dump /ma /u C:\dumps\process.dmp




Repeat typing gn until you get “there is no debugee” message. Your dump will be written in the location you specified above (C:\dumps\process.dmp).

Invalid URI error on attempt to create new web application

You may see the following error message on attempt to create new web application using SharePoint 2013 CA UI:

Invalid URI: The hostname could not be parsed.

Error message says: “Invalid URI: The hostname could not be parsed“, at the same time creation of web application using PowerShell may work just fine. This error can be caused by the fact that you have asterisk (“*”) as a value of Host name property in bindings of one of your existing web applications. Removing asterisk and leaving host name blank should resolve this issue.

PowerShell Script – Detect installed SQL Server Version and switch to appropriate setup directory

Some time ago I wrote a blog post where I explained how to change SQL Server instance collation for installed SQL server instance (see “Changing SQL collation for deployed instance without reinstall (almost)“). That post contained some scripting bits to detect installed SQL Server version and navigate to appropriate setup directory to facilitate collation change process. Recently I had a bit of time to consolidate these bits of PowerShell into one script which detects installed SQL Server version and changes directory to appropriate setup folder. Here you have it:

How To: Re-configure your K2 environment to use forms authentication

This blog post is just a short walk-through explaining how to switch your K2 environment from Windows to Forms authentication. Just to provide you an example of when you may want this – you can use this configuration when you want to get password prompt on token expiration while all your forms users working from domain joined workstations belonging to K2 server domain (that means that STS token refresh will be happening without any extra password prompts using existing Windows user credentials to obtain STS token).

Required steps are described in K2 documentation (look under “Forms Authentication”) but at the moment it does not mention some required steps which we will cover here.

To switch over to Forms Authentication you first need to navigate to K2 Management > Authentication > Claims > Issuers section of K2 Management site:

K2 Management – Issuers

There you can select K2 Forms STS and Click Edit button to enable “Use for Login” option of this issuer:

K2 Management – Edit K2 Forms STS issuer

Once you enabled this option, switch over to Authentication > Claims > Realms:

K2 Management – Realms

Here you need to edit every realm and link K2 Forms STS issuers to it (depending on your needs you can do that only for some realms):

K2 Management – Edit Issuer

Once you do that your realms should have K2 Forms STS visible in LINKED ISSUERS column:

K2 Management – Linked Issuers Column

At this point if you restart your browser and try to access K2 sites you will be presented with login method selection which looks as follows:

K2 Login Method Selection

If you don’t like this dialog or do not need to use multiple logon methods just uncheck
“Use for Login” option for K2 Windows STS issuer, with such configuration you will be getting immediate form authentication prompt on attempt to access K2 site (and after K2 STS token expiration). This is how it looks like:

K2 Forms Authentication Logon Page

Up to now we were following steps from K2 documentation and completed them but if you try to login with correct credentials you may see the following error:

Server Error – Claim mapping configuration cannot be found for this claim

Error message has the following text:

Server Error
Claim mapping configuration cannot be found for this claim. Claim information: Name='DENALLIX\administrator', Issuer='FormsSTS', Original Issuer='FormsSTS'. Please ensure that you have configured the K2 server as specified in K2 Help: Installation and Configuration > Configuration > SharePoint > Claims-based Authentication.
More Details
at SourceCode.Hosting.Server.Runtime.HostSecurityManager.GetClaimsUserName(String tokenXml, ClaimsTokenType tokenType, ClaimsVersion claimsVersion)
at SourceCode.Hosting.Server.Runtime.HostSecurityManager.AuthenticateIIdentitySession(String sessionCookie, String tokenXml, ClaimsTokenType tokenType, String connectionString, String authReqSource, ClaimsVersion claimsVersion)

This error and corrective actions to it do not mentioned in product documentation. To fix this you have to do the following:

1. Edit K2TokenService.exe.config located in “%K2_INSTALLATION_ROOT%\Token Service\Bin\” adding your K2 service and K2 application pool accounts into allowedCallers section as shown below:

K2TokenService.exe.config – allowedCallers

Here is sample of allowedCallers section text:


  <clear />

  <add value=”denallix\k2webservice” />

  <add value=”denallix\k2service” />


2. Save your changes and restart K2 Claims To Windows Token Service aka K2WTS (you can use PoSh command for that – Restart-Service K2WTS).

After performing these steps you will be able to logon to K2 sites using forms authentication.

StarWind VSAN overview

This article provides a basic overview of StarWind Virtual SAN (VSAN), a software-defined storage (SDS) solution from StarWind.

First things first: it is important to understand what SDS is

SDS is an umbrella term for software that enables policy-based provisioning of data storage independently of the underlying hardware. You can consider SDS a form of storage virtualization allowing to separate storage hardware from the software for its management. On top of that, SDS virtualization may also provide a rich policy-managed feature set including such things as data deduplication, replication, thin provisioning, etc.

SDS allows you to design architectures where software (instead of hardware) determines storage performance, availability, and resiliency. Usually, SDS systems are designed to perform on commodity hardware so that the software never gets dependent on proprietary hardware. However, the software you use may lock-in you to the particular vendor.

There are different implementations of SDS from different vendors. They can be divided on solutions offered by OS vendors (or public cloud providers) and ones developed by vendors focused purely on SDS.

For example, Microsoft introduced its SDS solution, Storage Spaces Direct, as a Windows Server 2016 feature (this version was RTMed in September 2016). However, you can find flaws even in the latest versions of their Storage Spaces Direct technology (for instance, deduplication did not work on ReFS until Windows Server 2019 release). Such issues may be a good reason why users opt for an alternative. Another thing about SDS is that you can access Storage Spaces Direct functionality only in Datacenter edition of Windows Server (high licensing costs).

On the other hand, StarWind VSAN is an example of SDS software developed by an SDS-oriented company. First released in 2005, it was one of the first practical implementations of SDS built with simplicity in mind. Any experienced administrator of Microsoft Hyper-V, VMware vSphere, or Citrix XenServer can configure StarWind VSAN easily. StarWind VSAN also allows you to start leveraging its full feature set starting with just two commodity servers as a foundation of highly-available (HA) SDS. Although this software uses the services provided by of Windows Server, you have a better version and edition choices, i.e., you can run it on any edition of Windows Server 2012 or 2016 (there is still even partial support for 2008 R2 which will probably end soon). As you can see, this specialized software found a way to the market earlier than Storage Spaces Direct, thereby developers had more time for adding improvements and refinements based on real-world usage and client base’s feedback.

You can have a full-fledged feature set including asynchronous replication, in-line, and offline deduplication, log structuring, and multi-tiered caching even in a minimal configuration of a two-node VSAN cluster. These features are present in other software solutions, but they often do not allow the two-node implementation scenario.

StarWind Virtual SAN features

  • Asynchronous replication replicates mission-critical data to remote disaster recovery (DR) site with minimal requirements for network bandwidth and hardware equipment, enabling you to perform replication over long-distance high-latency routes. Replication is performed asynchronously in the background using snapshots as a source. Features such as deduplication, snapshots, change block tracking in combination minimize the amount of data transferred to reduce WAN link usage. Snapshots secure data integrity.
  • In-line deduplication. Deduplication increases storage efficiency by saving space through elimination of repeating data. StarWind in-line duplication uses industry standard 4k blocks. Being combined with compression, it reduces the number of write operations, allowing to extend flash life span.
  • Log structuring write-back cache (LSWBC) optimizes highly randomized data flow generated by VMs. Disk storage handles highly randomized writes poorly; it uses RAM cache, leading to the risk of data loss. The use of SSD as the only approach is not always viable from the financial standpoint (overprovisioning/overuse of financial budget). LSWBS uses RAM and flash caching in conjunction with log structuring. LSWBC writes data to the circular buffer in RAM, organizes its flow sequentially, and gradually flushes it to the log disk (device from a tiny fraction of your storage). Log disk, in turn, sends data to the underlying storage where it eventually resides. Hence, it is possible to get high performance even with highly randomized workloads.
  • Two-tier server-side cache is a technology turning an SSD into level 2 cache. With the use of server RAM as level 1 cache, it absorbs excessive writes and reduces the number of write cycles impacting life span of SSD drives. Inexpensive commodity hardware is available, which means that you can use MLC flash instead of expensive SLC flash that gives more memory to meet workload requirements.
  • Multiprotocol: VSAN supports industry-standard uplink protocols. The following protocols are available: iSER, NVMe-oF, iSCSI, SMB3 (including RDMA-supporting SMB Direct and MPIO-utilizing SMB Multichannel), and NFS. Virtually unlimited use cases are possible: bare-metal, converged (“compute and storage separated”), hyperconverged, Clustered Shared Volumes for SOFS, VVols on top of iSCSI, SMB3 file servers and many others.

In terms of supported fabrics, you can use 1, 10, and up to 200 GbE or Infiniband.

Such feature set makes StarWind VSAN proposition quite compelling and competitive. It is an interesting option, especially in terms of design flexibility it provides and a variety of potential use cases.

I hope that this overview was useful and interesting. In case you want to know more about StarWind VSAN, you can get more information on StarWind Virtual SAN product page.