Hi Howard, On Fri, 4 May 2007 12:05:45 -0600, Howard Brazee <[EMAIL PROTECTED]> wrote:
>I would think that most reasons for blocking at particular rates would >be less important now with such cheap memory. I'm curious whether >the tape drives nowadays have sufficient buffering, not to mention how >the virtual swapping works to make our old calculations irrelevant. Here's some info about current tape drive buffer sizes. >From the SUN (STK) T10000 data sheet: "Speed-matching functionality supports high throughput rates and reduces media wear. The T10000 design includes two motor speeds and a 256- megabyte buffer that allows the drive to continuously and automatically adjust the buffer to match the speed of the data feed from the server." "Data transfer rate, native (uncompressed) 120 MB/sec Data transfer rate, (compressed, maximum) 360 MB/sec (future 4 Gb)" >From IBM TS1120 (3592-E05) announcement: "Large internal data buffer: ...512 MB internal data buffer. ...Along with enabling higher performance characteristics, the data buffer is designed to use support [sic] read ahead of approximately 500 MB of compressed data from tape and provide high performance random skip forward sequential (short hop) locates common in database search and tape software recycle operations." "native data rate...up to 100 MB/sec" "Note: The actual throughput a customer may achieve is a function of many components, such as system processor, disk data rate, data block size, data compressibility, I/O attachments, SAN, and the system or application software used. Although the drive is capable of a 100 MB/sec native data rate, other components may limit the actual effective data rate." Regards, Mike Baldwin Cartagena Software Ltd. www.cartagena.com ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
