Windows Server 2012 R2 storage changes announced at TechEd

Microsoft TechEd Trends driving IT todayMicrosoft TechEd USA is this week and they announced a number of changes to the storage services that come with Windows Server 2012 R2

  • Azure DRaaS - Microsoft is attempting to democratize DR by supporting a new DR-as-a-Service (DRaaS).  They now have an Azure service that operates in conjunction with Windows Server 2012 R2 that provides orchestration and automation for DR site failover and fail back to/from remote sites.  Windows Server 2012 R2 uses Hyper-V Replica to replicate data across to the other site. Azure DRaaS supports DR plans (scripts) to identify groups of Hyper-V VMs which need to be brought up and their sequencing. VMs within a script group are brought up in parallel but different groups are brought up in sequence.  You can have multiple DR plans, just select the one to execute. You must have access to Azure to use this service. Azure DR plans can pause for manual activities and have the ability to invoke PowerShell scripts for more fine tuned control.  There’s also quite a lot of setup that must be done, e.g. configure Hyper-V hosts, VMs and networking at both primary and secondary locations.  Network IP injection is done via mapping primary to secondary site IP addresses. The Azzure DRaaS really just provides the orchestration of failover or fallback activity. Moreover, it looks like Azure DRaaS is going to be offered by service providers as well as private companies. Currently, Azure’s DRaaS has no support for SAN/NAS replication but they are working with vendors to supply an SRM-like API to provide this.
  • Hyper-V Replica changes – Replica support has been changed from a single fixed asynchronous replication interval (5 minutes) to being able to select one of 3 intervals: 15 seconds; 5 minutes; or 30 minutes.
  • Storage Spaces Automatic Tiering - With SSDs and regular rotating disk in your DAS (or JBOD) configuration , Windows Server 2012 R2 supports automatic storage tiering. At Spaces configuration time one dedicates a certain portion of SSD storage to tiering.  There is a scheduled Windows Server 2012 task which is then used to scan the previous periods file activity and identify which file segments (=1MB in size) that should be on SSD and which should not. Then over time file segments are moved to an  appropriate tier and then, performance should improve.  This only applies to file data and files can be pinned to a particular tier for more fine grained control.
  • Storage Spaces Write-Back cache - Another alternative is to dedicate a certain portion of SSDs in a Space to write caching. When enabled, writes to a Space will be cached first in SSD and then destaged out to rotating disk.  This should speed up write performance.  Both write back cache and storage tiering can be enabled for the same Space. But your SSD storage must be partitioned between the two. Something about funneling all write activity to SSDs just doesn’t make sense to me?!
  • Storage Spaces dual parity - Spaces previously supported mirrored storage and single parity but now also offers dual parity for DAS.  Sort of like RAID6 in protection but they didn’t mention the word RAID at all.  Spaces dual parity does have a write penalty (parity update) and Microsoft suggests using it only for archive or heavy read IO.
  • SMB3.1 performance improvements of ~50% – SMB has been on a roll lately and R2 is no exception. Microsoft indicated that SMB direct using a RAM DISK as backend storage can sustain up to a million 8KB IOPS. Also, with an all-flash JBOD, using a mirrored Spaces for backend storage, SMB3.1 can sustain ~600K IOPS.  Presumably these were all read IOPS.
  • SMB3.1 logging improvements - Changes were made to SMB3.1 event logging to try to eliminate the need for detail tracing to support debug. This is an ongoing activity but one which is starting to bear fruit.
  • SMB3.1 CSV performance rebalancing - Now as one adds cluster nodes,  Cluster Shared Volume (CSV) control nodes will spread out across new nodes in order to balance CSV IO across the whole cluster.
  • SMB1 stack can be (finally) fully removed - If you are running Windows Server 2012, you no longer need to install the SMB1 stack.  It can be completely removed. Of course, if you have some downlevel servers or clients you may want to keep SMB1 around a bit longer but it’s no longer required for Server 2012 R2.
  • Hyper-V Live Migration changes - Live migration can now take advantage of SMB direct and its SMB3 support of RDMA/RoCE to radically speed up data center live migration. Also, Live Migration can now optionally compress the data on the current Hyper-V host, send compressed data across the LAN and then decompress it at target host.  So with R2 you have three options to perform VM Live Migration traditional, SMB direct or compressed.
  • Hyper-V IO limits - Hyper-V hosts can now limit the amount of IOPS consumed by each VM.  This can be hierarchically controlled providing increased flexibility. For example one can identify a group of VMs and have a IO limit for the whole group, but each individual VM can also have an IO limit, and the group limit can be smaller than the sum of the individual VM limits.
  • Hyper-V supports VSS backup for Linux VMs – Windows Server 2012 R2 has now added support for non-application consistent VSS backups for Linux VMs.
  • Hyper-V Replica Cascade Replication - In Windows Server 2012, Hyper V replicas could be copied from one data center to another. But now with R2 those replicas at a secondary site can be copied to a third, cascading the replication from the first to the second and then the third data center, each with their own replication schedule.
  • Hyper-V VHDX file resizing – With Windows Server 2012 R2 VHDX file sizes can now be increased or reduced for both data and boot volumes.
  • Hyper-V backup changes - In previous generations of Windows Server, Hyper-V backups took two distinct snapshots, one instantaneously and the other at quiesce time and then the two were merged together to create a “crash consistent” backup. But with R2, VM backups only take a single snapshot reducing overhead and increasing backup throughput substantially.
  • NVME support - Windows Server 2012 R2 now ships with a Non-Volatile Memory Express (NVME) driver for PCIe flash storage.  R2′s new NVME driver has been tuned for low latency and high bandwidth and can be used for non-clustered storage spaces to improve write performance (in a Spaces write-back cache?).
  • CSV memory read-cache - Windows Server 2012 R2 can be configured to set aside some host memory for a CSV read cache.  This is different than the Spaces Write-Back cache.  CSV caching would operate in conjunction with any other caching done at the host OS or elsewhere.

That’s about it. Some of the MVPs had a preview of R2 up in Redmond, but all of this was to be announced in TechEd, New Orleans, this week.


Image: Microsoft TechEd by BetsyWeber

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