Is it an End of Era for FC SAN?

In recent changes that have happened in the storage industry, it makes me believe that we are nearing an era which may be the end of SAN. If we look back & contemplate the way SANs were designed they were meant to solve just one of the many problems that are till today the unsolved problems. The SAN was originally meant to replace the locally attached storage, which to some extent has been successfully achieved.

The era of FC SAN was in full flow until advent of Gigabit & then 10 Gigabit Ethernet came into existence in around late 2010 decade. The NAS that existed even before SAN came into existence and continued to remain in the foray, but their age-old file system protocols were not enough to address the complexities of the mission-critical enterprise applications that require complex filesystem functionalities & security that were further made available by the advancing Linux technologies & the file systems designed on run on them, such as the LFS, ZFS, JFS, DFS, NTFS, JFFS, HPFS, HDFS, etc.

These required users to move to SAN to get access to centralized RAW volumes that can be mounted on the mission-critical application servers to make use of the newer filesystem. Things changed for SAN manufacturers as the Hard Disk density kept increasing & the cost of manufacturing kept falling. Today disk made for desktops are having size of >2TB with comparable performances to match that of the SAN based disks. So, the fundamental problem of requirement of RAW disk space kept diminishing over time, while users still continued using the centralized SAN.

The Ethernet technology advanced to make use of NIC bonding & eventually today has 40GB trunk speed to carry traffic meant for datacenters & cloud computing applications. This can be leveraged by the iSCSI SAN solution providers as well as the age old NAS solution providers to offer greater bandwidth for the hosts and their underlying applications. The NAS vendors aren’t left behind either. High performance file system protocols came into existence in the form of NFS V4 & SMB (CIFS) V3 that offered high throughput as well as addressed all the concerns that existed in the age old NAS filers.

The typical legacy block based RAID got replaced with file & object based RAID that offers much more flexibility & availability of data in the event of failures on the underlying Hard Disk system. Today’s NAS has ability to fine tune itself with whatever storage is placed in its backend. This only made NAS appliances more robust as they can offer not only file systems over the network but also the block based storage such as iSCSI as a unified all-in-one solution.

Software defined storage is further changing the paradigm for end-users and data-centers. It allows users to pick-up the hardware of their choice & with any backend storage, be it SATA, SAS or SSD or a low profile small form factor Flash Cards that can even be accommodated in the 2U form factor hardware and build their own NAS systems thus removing the vendor locking for costlier hardware.

All this only leads us to believe, is it end of era for FC SAN?

Write to us at smm@calsoftinc.com

Contributed by: Taizun Kanchwala | Calsoft Inc.

Software Defined Storage

Software-defined storage is latest buzz in storage industry. It gives rise to questions such as how software-defined storage is different from storage virtualization? Is this just old wine in new bottle?

Let us evaluate.

Storage started evolving since it came out of traditional computer systems and started getting deployed as external device. JBOD was simplistic external storage in early days. However, it came with couple of disadvantages: disk size was fixed and there was no protection against disk failures. This disk failure protection was then developed inside computer system as software in terms of RAID. However, since the computer system itself was vulnerable to failures, the disks in JBOD were still vulnerable to computer system failures resulting in data corruption. Next solution pushed the RAID software to HBA adaptors and then directly inside JBODs which were made more robust, failure tolerant and resistant. Thereafter all advanced features such as replication, snapshot, and deduplication started getting into JBOD converting them into sophisticated high end hardware storage arrays.

Though hardware storage arrays these days have many advance features, these features are applicable only at disk or logical unit (LU) level. Hardware arrays are not aware of contents within. This unawareness about content sometimes gives rise to inefficiency. E.g. many a times LUs of larger size are created for an application which doesn’t use that much of LU at least in beginning. Typically space required by application grows gradually. Till the time application uses full space of LU it is underutilized. Another example of inefficiency is storage arrays if capable of deduplication, may not be able to apply the dedup algorithm efficiently because contents of storage are not known.

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 new bottle.

Write to us at smm@calsoftinc.com

Contributed by: Tejas Sumant | Calsoft Inc.