Enterprises concerned about the cost implications of all-flash storage arrays can rest easy with Dell’s latest Storage SC9000 as it aims to beat the competition soundly on price. The new deduplication and compression features in its latest Storage Center OS (SCOS) 7 software make more efficient use of flash storage allowing Dell to claim a new industry low of only $0.45/GB.
These figures are calculated by applying an average 5:1 data reduction ratio and now make it a reality for enterprises to use high-performing all-flash arrays for primary storage. Even better, Dell claims that applying the same ratio to standard HDDs drops costs to a mere $0.10/GB.
SCOS 7 represents a major upgrade and offers a number of features that will appeal to Dell’s existing customers. Live Migrate means volumes can be moved non-disruptively between all SC4020, SC8000 and SC9000 systems while cross-platform replication allows volumes to be replicated between EqualLogic PS and SC appliances.
There’s more as the new HTML5-based Dell Storage Manager 2016 R2 software takes everything from the older Enterprise Manager tool and applies it to Dell’s entire storage portfolio. Along with a simplified deployment, this means you can manage all your SC, PS and FS systems from a single pane of glass.
Hardware and expansion
The SC9000 controller is deployed as a pair of well-specified Dell PowerEdge R730 2U rack servers both sporting dual 3.2GHz E5-2667 v3 Xeons and a hefty 256GB of system memory. For mirroring, the controllers each have cache cards with 4GB of battery protected NVRAM linked together via fibre GBICs.
Dedicated internal SSDs are used to run the SCOS 7 software and disk shelves are added across both controllers using dual-port SAS3 PCI-Express expansion cards. At present, you’re limited to a maximum of 960 SSDs and HDDs but Dell advised us that this will be pushed to beyond 1,024 drives with a planned future firmware upgrade.
Dell offers two choices of SAS3 disk shelves with the LFF 12-bay SC400 and SFF 24-bay SC420 while those more interested in capacity over performance can avail themselves of the mighty 84-bay SC280 which supports 6Gbps NL-SAS drives. Host connections are equally varied as Dell has 10GbE copper or SFP+, 8/16Gb/sec Fibre Channel or FCoE with a 25GbE option soon to be supported.
The new Storage Manager is well-designed and provides a unified view of all your Dell arrays
Storage tiers
The SC9000 supports up to three storage tiers and data is automatically migrated across them based on access frequency. Along with SLC and MLC SSDs, the SC9000 support cheaper, higher-capacity TLC SSDs and SCOS 7 now allows you to pin data to a specific tier.
Tier creation is automated as the SC9000 categorises drives by their type and interface. We tested using an all-flash array consisting of 22 800GB SLC SSDs and 42 1.9TB MLC SSDs which the SC9000 placed in the first and second tiers for us.
Even RAID array creation is automated as the SC9000 selects them to suit each tier with options for RAID0, 5, 6, 10 and dual-mirrored arrays. Physical storage is amalgamated into a single Disk Folder pool within which you can create multiple virtual volumes and map them to selected host data ports.
One thing we noted was data tiering doesn’t occur in real-time and is carried out at regular intervals using Storage Profiles. The system defaults to running profiles once at 19:00 each day but the schedule can be modified as required and jobs run as frequently as every five minutes.
The Storage Manager monitor shows a top IOPS performance for our dual server database test
Superb flash performance
With a pair of PowerEdge R720 servers connected to the SC9000 over dual MPIO 16Gb/sec FC connections, we saw Iometer report some very impressive throughput speeds. With one server running our Iometer workload, we saw random read and write rates of 24.6Gb/sec and 24.5Gb/sec.
Adding the second server delivered a high cumulative read throughput of over 45Gb/sec. To test maximum IOPS, we dropped the Iometer transfer request size from 256KB to 4KB and recorded 180,000 IOPS with one server and adding the second saw this increase to a cumulative 360,000 IOPS.
The SC9000 shrugged off our database workload test with Iometer recording a high 150,000 IOPS with one server. With the second server in the mix, we recorded a cumulative throughput of 300,000 IOPS showing no contention for resources.
Storage Profiles schedule data progression tasks and are used to apply deduplication, compression and QoS
Storage profiles
Data tiering and progression is controlled by Storage Profiles and Dell provides predefined ones for flash-optimised and standard storage types. These also manage deduplication and compression which can be enabled globally on the controllers or only for selected volumes.
To use deduplication you’ll need a minimum of six SSDs to store the hash dictionary on. As with data progression, deduplication isn’t dynamic and is only run when the profile schedule dictates.
The new Quality of service (QoS) feature will prove a valuable ally for controlling and prioritising volume usage. They’re simple to create and we could define limits based individually on values for MB/sec or IOPS or apply them both.
For multiple volumes, you can create a group policy and apply the same thresholds to all of them with one click. For critical volumes, you can also apply a threshold for latency and if breached, an alert will be issued.
Conclusion
The SC9000 combines an impressive all-flash performance with a remarkable expansion potential. With the latest SCOS 7 software at the helm, it also offers a wide range of features including automated data tiering while the new deduplication can make big savings on storage.
Dell’s competition will also have a tough job matching the SC9000 for value with it offering the lowest all-flash storage costs around. In fact, Dell is so confident that flash is the way to go that it will provide free replacements for any units that fail within the warranty period.
