Questions_and_Responses_2.doc

SSA-RFP-13-0017

Amendment 02

Answers to Questions – June 28, 2013 Question #1

Section C-3.4.1.3 Request: As a follow-up to the Government's response to Question 3, Section C-3.4.1.3 the government states "Each virtual tape drive must support a minimum (read/write) data transfer rate of 60 MB/second for a single stream."

It should be noted that single stream performance is highly dependent on a variety of factors unique to each data center environment and not related to the VTL. These characteristics include the attributes of the mainframe host, the layout of the channel architecture, the status of the host and the VTL, and many other factors. Mainframe tape users typically configure a virtual tape library with a virtual drive count consistent with the needs of specific applications. These factors make the measurement of aggregate VTL performance a far more relevant performance metric as aggregate performance reflects typical mainframe device usage.

It is requested that the Government revise this requirement C-3.4.1.3 to read: "All VTL subsystems must support a minimum of 256 virtual tape drives. Each set of virtual tape drives must support an aggregate (read/write) data transfer rate of 340 MB/second."

Government Response:

The Government has amended the requirement in C-3.4.1.3 to read, “Each virtual tape drive must support a minimum (read/write) data transfer rate of 60 MB/second for a single stream under ideal conditions, excluding external factors. External factors include, but are not limited to, the attributes of the mainframe host, the layout of the channel architecture, the status of the host and the VTL. Each set of 256 virtual tape drives, on a single server, must support an aggregate (read/write) data transfer rate of 340 MB/second. SSA expects single stream drive performance to degrade as more devices are used. However, the transfer rates of individual virtual tape drives should not degrade by more than 30% until more than 16 streams are active at a given time.”

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