As the Disk Spins: IBM Disk Drive Announcement for Storwize V5000 and V7000 Storage Systems

On July 2, 2019, IBM announced that 15K RPM hard disk drives would no longer be available for new orders of its Storwize V5000 and V7000 storage systems, US announcement letter 119-048.  Why did IBM make this announcement and what does it mean for IBM i customers?

Disk drives for IBM i are currently available in 3 formats: 

  • Hard Disk Drives (HDD’s) are mechanical spinning magnetic platters that are available in 3 speeds – 7,200 RPM, 10K RPM, and 15K RPM. 15K RPM drives are traditionally used with IBM i servers. IBM i is called a Database Machine because its primary job is to access, manipulate and store data for transactional workloads.  Fast, 15K RPM, disk drives are needed to support the workload and keep the server humming.  7,200 and 10K RPM drives are rarely used on IBM i servers, but have a purpose for archived data that have low access requirements.

  • Solid State Drives (SSD’s) are electronic non-volatile memory storage devices that emulate HDD’s. SSD’s use the SAS (Serial Attached SCSI) protocol to interface with the server, the same protocol used by HDD’s.  SSD’s are much faster than HDD’s because they operate at electronic speed versus the mechanical speed of HDD’s.  The time to access data on HDD’s is composed of seek time, the time to position the disk head to the requested track on the platter, and latency, which is the time to position the head over the correct sector on the track.  SSD’s get their speed by eliminating seek time and latency and also by the improvement of electronic versus mechanical data access.

  • Flash Drives are electronic non-volatile storages devices that do not emulate HDD’s, but instead use a protocol, NVMe (Non-Volatile Memory Express), designed to take advantage of the low latency and parallelism of memory storage devices. While the underlying storage technology is the same in SSD’s and Flash drives, NVMe (16GBPs) protocol is faster than SAS (up to 12GBPs).  Indications are that Flash storage will be the long-term storage direction and that SSD’s are just an interim device bridging the mechanical and electronic storage medias.

Why are 15K RPM hard disk drives no longer available for the Storwize V5000 and V7000?  15K RPM drives are for customers who want the fastest drives.  15K RPM HHD’s were once the fastest drives available for IBM i servers, but gave way to SSD’s and flash drives.  Customers wanting the fastest drives are now ordering SSD’s or Flash.  The second reason is product supply.  With lower demand for 15K RPM drives, the supply has shrunk and indications are that this will continue.  At some point the cost of SSD’s and Flash will match the cost of HDD’s and then HDD’s will become, technically and financially, obsolete.

Storwize V5000 and V7000 do attach to IBM i servers, but IBM i customers mostly use internal storage because it is faster, less expensive and easier to set up and manage.  15K RPM HDD’s are still available for IBM i servers, but I think the indications are clear that they will also be withdrawn at some point for the same reasons that they were withdrawn from the V5000 and V7000.  I encourage customers buying new IBM i servers to get two quotes, one with HDD’s and the other with SSD’s.  HDD’s are currently less expensive but many customers agree that the speed improvement of SSD’s is well worth it.  NVMe is built into IBM Power9 servers, but is not supported by IBM i.  Watch this space for future announcements.


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