The following message is a courtesy copy of an article that has been posted to bit.listserv.ibm-main,alt.folklore.computers as well.
[EMAIL PROTECTED] (Richards.Bob) writes: > 3880-xx Controller series followed by the 3990-xxx series > > DASD was 3380-D, 3380-E, 3380-J, 3380-K, 3390-1, 3390-2, 3390-3 (today's > major image) and 3390-9 (a true SLED pulled by crippled and maimed dogs) > > Yes, the 3380s had four paths. Do not recall if it was ever increased. 3830 disk controller had dual channel along with "string switch" for 3330 ... allowing for four paths total (i.e. string connecting to two different controllers, each of which could connect to two different channels) 3880 disk controller had four channel interfaces ... and 3380 "string switch" (a-box) allowed 3380 string to be connected to two different controllers for eight total paths. Evolution of the DASD storage control http://www.research.ibm.com/journal/sj/282/ibmsj2802C.pdf not to be too harsh about comment in the above about 3880 having better performance ... but some recent posts that touched on getting 3880 out the door ... as well as little discussion of dynamic pathing http://www.garlic.com/~lynn/2007h.html#1 21st Century ISA goals? http://www.garlic.com/~lynn/2007h.html#3 21st Century ISA goals? http://www.garlic.com/~lynn/2007h.html#4 21st Century ISA goals? http://www.garlic.com/~lynn/2007h.html#5 21st Century ISA goals? http://www.garlic.com/~lynn/2007h.html#6 21st Century ISA goals? http://www.garlic.com/~lynn/2007h.html#9 21st Century ISA goals? IBM Jargon: A-Box n. A primary storage unit: the one closest to the controller. Most 370 storage peripherals come in two flavours. The A-Box (also called head of String, or Model A) either houses the controller (e.g., 3422), is the controller (e.g., 3480), or connects to the controller. The B-Box (Model B) is used for extending the string. Some strings can be connected to the controller at both ends, in which case the unit at the end of the string is usually a Model D. ... snip ... 3380 "history" here with A & B boxes: http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3380.html http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3380b.html http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3380c.html minor mention of a-box, head-of-string function: http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3380d.html http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3380e.html from above: A string of Standard model 3380s can consist of a single 3380 Model A04 or AA4 and up to three 3380 Model B04 units. A string of Extended Capability 3380s can consist of one 3380 Model AD4 or AE4 and up to three 3380 Model BD4 and BE4 units, in any combination. Two strings of 3380s can be attached to each storage director of a 3880 Model 3 or cache storage control Model 23. An A04 string is not supported by the Model 23. Strings headed by an AA4, AD4 or AE4 must attach to two storage directors (usually on two separate 3880 Storage Controls). An AA4 string and an Extended Capability string can be attached to the same storage directors. ... snip ... at one point i made a forey into redoing the (3880) controller dynamic pathing architecture implementation ... as part of significantly extending & simplifying ("dynamic pathing simplification") capability for virtualized operation ... but got into all sort of issues regarding compatibility with implementation already in the field. ---------------------------------------------------------------------- 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
