Welcome to the ITFreeTraining video on the new features added to Windows Storage Spaces
in Windows Server 2012 R2. Storage spaces was first introduced in Windows server 2012
and Windows 8, and is a system that allows multiple hard drives and solid state drives
to be grouped together.
In this video I will look at the five new features of Windows Storage Spaces added in
Windows Server 2012 R2. Most of the features shown are transparent and automatically available
to the administrator. There are two features, however, which the administrator can choose
if they want to use the additional functionality.
The first feature that I will look at is Storage Tiers. Storage Tiers stores data that is accessed
more often on solid state drives and less-used data on traditional hard drives. By using
a mixture of solid state and hard drives, this can significantly improve access times.
In this example, I have a number of hard drives and solid states drives connected to the system.
There are 6 hard drives and 4 solid state drives. All these drives are combined together
using Windows Storage Spaces in a single storage pool.
In this case, since the solid state drives are faster than the hard drives, you want
the solid state drives to be used for files that are accessed frequently. To do this,
drives can be divided into two tiers. The solid state tier and standard hard disk tier.
This allows storage spaces to move files that are accessed frequently on to the solid state
tier and put less used files on the hard disk tier.
In this example, a simple virtual disk and a mirrored virtual disk were created. Storage
Tiers currently does not support parity. When virtual drives are created, Windows will ask
how much space should be used on the solid state tier and how much should be used on
the hard disk tier. The administrator is free to choose this amount.
The next feature that I will look at is write-back cache. This features allows solid state drives
to be used as a cache for the mechanical hard drives. This cache is used for small random
writes. Often in enterprise systems, small random writes form a large percentage of the
work load. Since mechanical drives are slow for random write, having a lot of small random
writes slows down the overall system. For this reason, having these random writes cached
on solid state drives before being transferred to the slower mechanical drives does a lot
to speed up the overall responsiveness.
The good news with write-back cache is that it is configured by default. Whenever you
create a new virtual drive in Windows Server 2012 R2, the write cache will be enabled using
the solid state drives. This feature is also used with Storage Tiers. When you create a
virtual disk using Storage Tiers a larger write cache will be created on the solid state
drives.
The important point to remember is that redundancy needs to be maintained even when using a combination
of solid state and hard disk drives. For this reason, the write back cache requires the
following. For a simple space it requires one solid state drive. A two way mirror requires
two solid state drives, and a 3 way mirror requires 3 solid state drives. If you do not
have the required number of solid state drives, the write-back cache is disabled since data
redundancy cannot be achieved.
The next new feature is parity support for failover clusters. This means that Windows
Server 2012 R2 now supports simple, mirror and parity for drives created for clusters.
Previously in Windows Server 2012, parity was not supported for clusters. This gives
the administrator more redundancy options using Windows Storage Spaces with clusters
in Windows Server 2012 R2.
The next feature is dual parity. Parity is available in Windows Server 2012 - allowing
the storage pool to keep operating with the loss of one drive. In Windows Server 2012
R2, support has been added to store parity on 2 drives. This allows a virtual drive with
parity to survive 2 drive failures.
When creating a virtual disk using the parity layout, the administrator has the option to
use dual parity. Dual parity does require a least 7 drives in the storage pool. If you
have less than 7 drives, only single parity will be available.
The last new feature in Windows Storage Spaces is automatic rebuilding of storage spaces
from storage pool free space. What this essentially means is that when a drive fails and a rebuild
needs to occur, the drive can be rebuilt to free space - assuming enough disks are in
the storage pool and there is enough free space. If a hot swap drive was in storage
space, the data from the failed drive would be rebuilt onto the hot swap drive. Using
a hot swap means that a large number of drives may need to be read and written to a single
drive. This is a very slow process.
In Windows Server 2012 R2, rather than use a hot swap drive, the data from the missing
drive is instead copied to the free space in the storage space, meaning there is no
need to have hot swap drives.
Let's consider the following example. There are 4 drives in the set. If the second drive
was to fail, the data on this drive would need to be rebuilt onto the other drives.
Rather than copying this data to another free drive like a hot swap drive, instead, the
data is rebuilt to the free space. As shown, the 3 drives have free space so the data on
the second drive is recreated on the other drives. Since the data is being created on
3 drives, this is a lot faster than recreating the data on the one replacement drive and
also eliminates the need for hot swap drives. All you need to do is ensure that there is
enough free space and disks in the storage space to tolerate failed drives.
That covers all the new features of Windows Storage Spaces in Windows Server 2012 R2.
I hope you have found this video informative and I hope to see you in other videos from
us from Windows Storage Space. Thanks for watching and see you next time.