Storage Spaces Technology Simplified

 

Storage Spaces enables the use of multiple disks of different sizes and interfaces by pooling them together so that the operating system sees them as one large disk. Disks with USB, SATA, SCSI, iSCSI, and SAS are among the supported interfaces.  A group of different physical disks is called a storage pool, one or more storage spaces can be created on top of the storage pool.  Storage spaces will appear as virtual disks, these disks can be further configured to create one or more logical volumes and presented to operating system.

SP-Pool

As shown in the above picture, storage pool can be created from a bunch of physical disks connected to either a Windows 2012 standalone server or Windows 2012 failover cluster nodes. Any available physical disk that is not formatted can be an eligible candidate for the storage pool. Once the operating system detects eligible physical disks connected directly, it will create a Primordial storage space.

Consider Primordial storage space as a holding pool for all unallocated disks that are connected to the currently managed server. You must create new storage pool by grabbing the disks from Primordial pool, because the Primordial pool itself will not allow you to create virtual disks.

From the storage pool, one or more virtual disks can be created which will be later presented to the operating system as one or more volumes. The virtual disks provide different type of storage layout depending upon the resiliency such as Simple, Mirror or Parity. The layout options resembles RAID0, RAID1 and RAID5 however it does not create a mirror copy to a specific mirror disk as in RAID1 or write parity in sequence as in RAID5.   The storage space technology randomly picks disks for writing the mirrored blocks or stripe blocks.

One or more volumes can be created from the available virtual disk depending upon the requirements. Volumes created in storage space supports NTFS and ReFS formats however volumes formatted with ReFS cannot be added to Cluster Shared Volumes (CSV).

Storage Tiers in Windows 2012 R2 Preview

Storage tier is a new feature available in Windows server 2012 R2 Preview which allows creation of virtual disks comprised of two tiers of storage (HDD and SSD). Frequently accessed data will be automatically moved to the SSD tier and less frequently access data will be moved to HDD tire. Storage Spaces technology transparently moves data at a sub-file level between the two tiers based on the frequency of data accessed.

SP-Tier

As shown in the above picture, a mixture of HDD and SSD disks are picked to create storage pool. Then while creating the virtual disk, you may specify the storage space required from each tier. For instance, the virtual disk selected with simple layout will have 40 GB from SSD tier and 200 GB from HDD tier. The storage technology runs an optimization sequence to monitor the frequently used blocks and moves the frequently used blocks to the SSD tire. Storage Space also uses the SSD tier to create a write-back cache which buffers random writes to SSD disks to reduce the latency of writing the data directly to HDDs.

 

 

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About Jayachandran PK
My passion is for Microsoft technologies and how if properly implemented, they can provide actual value for an organization especially in the field of infrastructure, virtualization and system monitoring. I work for the biggest Microsoft partner in Kuwait, specialized in project consultation and implementation services for enterprise clients. When I'm not at work, I try to contribute back through a charitable organization dedicated to prompting cultural values of Kerala. In my free time, I dabble in gardening and am also an avid solar power aficionado.

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