Value of Spectrum Control to Spectrum Scale

Today if you are a customer in a sector like financial, retail, digital media, biotechnology, science or government and you use applications like big data analytics, gene sequencing, digital media or scalable file serving, there is a strong possibility that you are already using IBM Spectrum Scale (built upon General Parallel File System or GPFS).

Spectrum scale

A question foremost in your mind may be: “If Spectrum Scale has its own element manager – the Scale GUI, what would I gain from using Spectrum Control?”
The Spectrum Scale GUI (available for version 4.2 and later versions of Spectrum Scale) focuses on a single Spectrum Scale cluster. In contrast, the Spectrum Control GUI offers a single pane-of-glass to manage multiple Scale clusters (including version 4.1.0 of Spectrum Scale), it gives you higher level analytics, a view of relationships between clusters, the relationships between clusters and SAN attached storage.  In future, we expect to extend this support to Spectrum Scale in hybrid cloud scenarios where Spectrum Scale may be backed by say Amazon S3 or IBM private cloud storage.

4 primary areas where Spectrum Control adds value today:

Spectrum Control for Scale

  • Performance monitoring: If you have multiple Spectrum Scale clusters you can use Spectrum Control to manage cross cluster traffic since Spectrum Control charts I/O rates and response times. You can also monitor the performance of the file systems and nodes that make up each cluster. Since Spectrum Control can monitor block storage devices, you can monitor the performance of SAN attached volumes that are backing the NSDs in the cluster, as well as the fabrics used to connect the NSD servers to the block storage.
  • Capacity management: If you have say an IBM FlashSystem providing block storage to your Spectrum Scale clusters, you can monitor these block volumes backing the Scale NSDs. You can identify when you will run out of inodes or when a file system runs out of space. You can view the size and age of snapshots in a file system perhaps to identify candidates for deletion and space reclamation. You can view file system relationships, quotas, snapshots, NSDs being used to build a pool, the number of nodes using the file system, compare pools across the Scale cluster.
  • Alerting: Spectrum Control enables meaningful alerts by nodes, NSD, file systems, file sets. You can identify (though not alert upon) which file sets will run out of available inodes, identify filesets not linked into their file system, identify (though  not alert upon) which filesets have reached soft/hard quota limits. As an example, you may want a warning alert notification sent to your operations team when the used space under Spectrum Scale crosses 80%, but when the used space crosses 90% you may want a critical alert notification sent to your storage administrator. Spectrum Control handles all of these scenarios.
  • Showback & chargeback: Spectrum Control offers the ability to categorize storage resources used by Spectrum Scale into “application groups” and “department groups” which in turn is a key enabler of showback and chargeback.  The benefit is that now a Spectrum Scale administrator can identify issues that impact specific applications.

If you like what you hear so far but don’t have an on-premise version of Spectrum Control in-house, check out our Spectrum Control Storage Insights offered as SaaS and give it a risk free 30 day test drive.

How Spectrum Control adds value to IBM EasyTier

A question that often comes up from customers is “How does the tiering in Spectrum Control differ from what is available in EasyTier as part of SVC/Storwize?”  This is a valid question which merits a detailed answer. Before getting into the specifics of EasyTier let us get some terminology out of the way.  We all agree that IBM SAN Volume Controller (SVC) or Storwize will act as a storage hypervisor and will allow you to virtualize your existing legacy storage whether it be from EMC or HDS or Oracle.

SVC and IO groups

In the above diagram, legacy EMC or HDS storage shown as DISK Subsystem will have disks (spinning HDD and NAND flash based SSD) and RAID controllers, the disk subsystem exposes SCSI LUNs to IBM SVC.  SVC views the world in terms of managed disks (mdisk) and groups of mdisks constitute a storage pool.  These mdisks in turn can be divided into “extents” and these extents can be combined to create virtual volumes which are each assigned a logical unit number (LUN).  Your host application whether it be DB2 or Oracle or SAP sees only these virtual volumes exposed by IBM SVC – it doesn’t know nor should it care about the internal workings of SVC.


As a storage administrator you decide to derive the benefits of EasyTier.  You may choose to create a “multi-tier storage pool” comprising HDD mdisks and SSD mdisks and enable EasyTier on it.  EasyTier will monitor the I/O and latency on back-end extents of all volumes within this pool.  It will dynamically migrate “hot” extents to a faster disk tier within the pool, “cold” extents will be moved from faster tier mdisks to slower tier mdisks.  In other words EasyTier is doing sub-LUN level optimization within the boundaries of a storage pool for workloads that are not cache-friendly.

Spectrum Control adds further value to EasyTier in the following ways:

  • Enabling optimization of entire volumes across the boundaries of storage pools giving you the added flexibility to migrate a “hot volume” across storage pools
  • Balancing workloads across multiple pools to help you avoid hotspots and bottlenecks
  • Take corrective action in case of overloaded pools (pools which say may not have enough SSD capacity in a pool configuration)
  • Providing visibility into the type of disks (near-line, SAS, SSD) that constitute the storage pool and helps you understand how volumes are residing within different disk tiers.

If you have Spectrum Control in-house try this all out for yourself, if you don’t and want to experiment with the SaaS equivalent namely Spectrum Control Storage Insights check out the blog post from my colleague Jenny Shaw.  With a newly introduced entry price of $250 dollars per month for the first 50 terabytes of usable storage, you can’t go wrong giving Spectrum Control Storage Insights a test drive.