Software Defined Storage
Software defined storage is the latest
buzz in the storage industry. It gives rise to questions such as how
software-defined storage is different from storage virtualization? Is this just
old wine in a new bottle? Let us evaluate.
Since the storage was developed it
has continued to evolve and being deployed as an external device. JBOD was a simplistic
external storage in the early days. However, it came with a couple of
disadvantages: disk sizes were fixed and there was no protection against disk
failures. RAID, the disk failure protection system, was born. However, RAID did
not solve the problem computer systems themselves being susceptible to
failures. This made RAID software be placed inside HBA adaptors, and then
placed inside JBODs making them more robust,
failure tolerant and resistant. This allowed more advanced features such as replication,
snapshot, and deduplication.
An example of this underutilization
is seen when storage arrays are unable to deduplicate as they are incapable of
deduplication, because the contents are unknown.
Typically, the space required by an application
grows gradually. Until the time application uses the full space of LU it is
underutilized. In recent days this provisioning solved the space efficiency
problem but no other problems such as object specific replication, deduplication,
and snapshotting. In recent past, cloud computing gave rise to need of
multi-tenant storage. Multi-tenant storage with space efficiency still remains
a challenge with traditional storage arrays.
Software-defined storage has evolved
to address these problems by breaking LU as operational boundary. With
software-defined storage, storage arrays will be able to receive content
information and policies and apply them as appropriate.
Let us take an example of hypervisor
application. Virtual machines are objects of hypervisor ecosystem and undergo
various transitions during their life time based on application they are
running. Apparently, data associated with VMs also needs to take part in this
transition such as replication, snapshotting, cloning, and migration. If VM
data is sitting on software-defined storage then these all requirement can be
set as policies of data specific to VM. Software-defined storage seems to be
really addressing the issues that were unaddressed till date; hence it is not
just old wine in a new bottle.
Contributed by: Tejas Sumant | Calsoft Inc.
