Windows Server 2012 64TB NTFS Volumes and the Flush Command

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As you might very well have read or even tried you can use 64TB volumes in Windows Server 2012 in a supported scenario. You can do more, NTFS is quite capable of this. I created a 300TB LUN once that I could format up to 256TB Smile But as no one can realistically stress test this for real, it’s not supported.

That’s a lot of storage and data. It’s also expensive and incurs some risk … all that data on one volume. Windows 2012 tries to address the cost issue with commodity storage in combination with the excellent resilience of storage space to reduce both cost and risk.

Apart from introducing ReFS they also did some work on NFTS to help with reliability:

  • A new approach for detecting and repairing corruptions in NTFS which optimizes uptime through on line repair and with spot fixing that keeps off line repairs minimized and very short.
  • Using the flush command instead of FUA.

In this post this we’ll focus on the flush command.

Flushing Your Data

No, not that kind of flushing Smile You have always been able to “throw” data away with some very bad practices and unreliable technology, no need for much innovation there.

I’m talking about the fact that NTFS in Windows Server 2012 has switched to the flush command instead of relying on Forced Unit Access (FUA) to increase reliability for SATA disk and performance with SCSI disks. The good news is you don’t lose anything and gain on both fronts. Especially making cheaper SATA disks more reliable is a big one. It allows SATA disks to be used in business/enterprise scenarios and as such helps reduce costs.

What is Forced Unit Access (FUA)?

Well it’s a flag that indicates a given write should go directly to media, writing through a devices write cache. The NTFS Journaling File System uses FUA to guarantee write ordering which is important to maintain its metadata integrity. It was  implemented in the SCSI (T10) specification but not in the original  ATA (T13) specification. This was added in the 2002 version of the ATA specs but FUA has never been guaranteed to implemented on all ATA devices and as such Windows could not rely on it being there with ATA/SATA disks. As a result it was never used by Windows with SATA disks.

That meant that with SATA disks there is a bigger change of corruption due to a power failure or the likes as NTFS was designed to rely on FUA implementation for robust metadata writes.With ever increasing capacity needs an larger SATA disk being needed and used for business purposes something had to be done. So with Windows Server 2012 (and Windows 8) NTFS switched to using a  flush command to the drives write cache instead of using FUA.

The Benefits

  1. The switch to using the flush command for all operations that require write ordering to ensure file system metadata integrity realizes better reliability and robustness when using commodity SATA storage as it reduces possibility of corruption due to power loss
  2. It Improves performance on SCSI devices because it allows the disk to cache data for as long as safely possible instead of having to do write-through using FUA

Prepare For Windows Server 2012 This Fall

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With the academic year in full swing and no lack of material we need to learn and study Microsoft is giving you a helping hand by providing a huge pool of resources. There’s TechNet, Evaluation software but also the Microsoft Virtual Academy.

To reward you for your hard work you get a cinema ticket to go relax at the movies. Click on the banner for more information on this.

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The nice thing about the Microsoft Virtual Academy that you can do study the modules at your own pace and at your own moment of choosing. Combine this with TechNet Virtual labs and you have a lot of resources at your finger tips to learn even more even if you don’t have the room or resources to build a (home) lab.

If all that technology left you wanting to get some hands on with Windows Server 2012 you can also register for an IT Camp. There should be some more of them coming I’ve read on the site. With Mike Reseler  (@MikeResseler) & Arlindo Alves@aralves) delivering those IT Camps you’ll be in good hands. Happy studying and have fun at the movies Winking smile

Cluster Validation Failure while setting up a Windows 2012 Continuous Available File Share: The password does not meet the password policy requirements

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We were installing a Windows Server 2012 cluster in a W2K8R2 domain and while we were checking out our work by running the cluster validation we got one warning we’ve never seen before:

Validate CSV Settings

Description: Validate that settings and configuration required by Cluster Shared Volumes are present. This test can only be run with an administrative account, and it only tests servers that are cluster nodes.

Start: 9/24/2012 5:01:18 PM.

Validating Server Message Block (SMB) share access through the IP address of the fault tolerant network driver for failover clustering (NetFT), and connecting with the user account associated with validation.

Begin Cluster Shared Volumes support testing on node server1.test.lab.

Failure while setting up to run Cluster Shared Volumes support testing on node server1.test.lab: The password does not meet the password policy requirements. Check the minimum password length, password complexity and password history requirements.

Begin Cluster Shared Volumes support testing on node server2.test.lab.

Failure while setting up to run Cluster Shared Volumes support testing on node server2.test.lab: The password does not meet the password policy requirements. Check the minimum password length, password complexity and password history requirements.

This test requires more than one node. If your cluster contains more than one node, please run validation tests again with more than one node specified.

Now as it turns out this Active Directory domain does enforce some lengthy and complex passwords. By this they are basically driving the admins to use pass sentences which are lot more secure. That also means that the account we are using to run the validation have adequate lengths & complexities.

So, what if we tune down the password length requirements and than run GPUDATE from an elevated command prompt on all nodes of the cluster? Bingo! The cluster valid now passes with flying colors.

I’m guessing that perhaps the local doesn’t have a strong enough password to meet the requirements. But this is just guessing. This is the account that is involved in reducing the clusters dependency on Active Directory so that CSV for example can come on line even if there is not domain controller to contact. Hence my guess that this is related. This did not happen in a lab environment so I’m not going to change the password on all nodes to a more complex one. That is for a lab Smile

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Continuously Available File Shares Don’t Support Short File Names – “The request is not supported” & “CA failure – Failed to set continuously available property on a new or existing file share as Resume Key filter is not started.”

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If you ever get the following error while trying to create a Continuously Available File Share in Windows Server 2012  “The request is not supported”

If on top you find this entry in the Microsoft-Windows-SmbServer/Operational event log:

Log Name:      Microsoft-Windows-SmbServer/Operational
Source:        Microsoft-Windows-SmbServer
Date:          24/09/2012 17:56:59
Event ID:      1801
Task Category: (1801)
Level:         Error
Keywords:      (8)
User:          SYSTEM
Computer:      server1.lab.test
Description:
CA failure – Failed to set continuously available property on a new or existing file share as Resume Key filter is not started.

First of all check  with fsutil if you have short file names enabled on the volumes on which you are trying to create the continuous available file share:

  • Log on to the node running the File role and open a elevated command prompt to run the following on the volume/partition in play, F: in this example.

fsutil 8dot3name query F:
The volume state is: 0 (8dot3 name creation is enabled).
The registry state is: 2 (Per volume setting – the default).
Based on the above two settings, 8dot3 name creation is enabled on F:

  • I chose to enable or disable short file names per volume

fsutil 8dot3name set 2
The registry state is now: 2 (Per volume setting – the default).

  • Disable short file names on the volume at hand

fsutil 8dot3name set f: 1
Successfully disabled 8dot3name generation on f:

  • Remove any short file names present on this volume

fsutil 8dot3name strip f:
Scanning registry…
Total affected registry keys:                   0
Stripping 8dot3 names…
Total files and directories scanned:            6
Total 8dot3 names found:                        3
Total 8dot3 names stripped:                     3
For details on the operations performed please see the log:
“C:UsersUSER~1AppDataLocalTemp28dot3_removal_log @(GMT 2012-09-24 18-40-05).log”

  • Now, move the role over to the next node to rinse & repeat

fsutil 8dot3name set 2
The registry state is now: 2 (Per volume setting – the default).

fsutil 8dot3name set f: 1
Successfully disabled 8dot3name generation on f:

fsutil 8dot3name query f:
The volume state is: 1 (8dot3 name creation is disabled).
The registry state is: 2 (Per volume setting – the default).
Based on the above two settings, 8dot3 name creation is disabled on f:

fsutil 8dot3name strip f:
Scanning registry…
Total affected registry keys:                   0
Stripping 8dot3 names…
Total files and directories scanned:            6
Total 8dot3 names found:                        0
Total 8dot3 names stripped:                     0
For details on the operations performed please see the log:
“C:UsersUSER~1AppDataLocalTemp38dot3_removal_log @(GMT 2012-09-24 18-44-36).log”

I know this now because I hit the wall on this one and Claus Joergensen at Microsoft turned me to the solution. He actually blogged about this as well, but I never really registered this until today.

Disable 8.3 name generation

SMB Transparent Failover does not support cluster disks with 8.3 name generation enabled. In Windows Server 2012 8.3 name generation is disabled by default on any data volumes created. However, if you import volumes created on down-level versions of Windows or by accident create the volume with 8.3 name generation enabled, SMB Transparent Failover will not work. An event will be logged in (Applications and Services Log – Microsoft – Windows – ResumeKeyFilter – Operational) notifying that it failed to attach to the volume because 8.3 name generation is enabled.

You can use fsutil to query and setting the state of 8.3 name generation system-wide and on individual volumes. You can also use fsutil to remove previously generated short names from a volume.

There’s also a little note here http://support.microsoft.com/kb/2709568

SMB Transparent Failover

Both the SMB client and SMB server must support SMB 3.0 to take advantage of the SMB Transparent Failover functionality.
SMB 1.0- and SMB 2.x-capable clients will be able to connect to, and access, shares that are configured to use the Continuously Available property. However, SMB 1.0 and SMB 2.x clients will not benefit from the SMB Transparent Failover feature. If the currently accessed cluster node becomes unavailable, or if the administrator makes administrative changes to the clustered file server, the SMB 1.0 or SMB 2.x client will lose the active SMB session and any open handles to the clustered file server. The user or application on the SMB client computer must take corrective action to reestablish connectivity to the clustered file share.
Note SMB Transparent Failover is incompatible with volumes enabled for short file name (8.3 file name) support or with compressed files (such as NTFS-compressed files).

Frankly, all my testing of Continuous available share, from the BUILD conference till RTM setups have been green field, meaning squeaky clean, brand new LUNs. So this time, in real live with a LUN that has a history in a Windows 2008 R2 environment I got bitten.

So, read, read and than read some more Smile is my advise and be grateful for the help of patient and knowledgeable people.

Anyway, It’s full steam ahead here once again getting the most out of our Software Assurance by leveraging everything we can out of Windows Server 2012.