🚀 go-pugleaf

In article <1992Aug29.210553.8744@rhein-main.de>, vhs@rhein-main.de writes...
>I need to design a retrieval system for ~15TB of data, of which ~5TB are
>retrieved with a high frequency (25 requests/second) and an access time
>of avg. 30 seconds (max. 120 seconds). Retrieval lacks any locality, so the
>5TB are real random-access. The rest of the data is still accessed at a
>rate of 5 requests/second. Here, too, access is completely random.
>So far I've come up with the following ideas:
> 
>1) Use large (10GB) WORM jukeboxes with many pickers (~40),
>   many drives (~150) and a *real* intelligent scheduler. No cache.
> 
>2) Use 1) for the less-often-retrieved data, and several 625MB-OD
>   jukeboxes with even more drives and a less intelligent scheduler.
> 
>I figure that doing some 25 media changes a second would be a real
>performance killer. Due to the response time restrictions (30 seconds)
>there is hardly a chance to build a decent queue for pending requests
>and schedule them appropriately.
>So what we really need is 5TB of something like a huge, if slow, hard disk.
>Is there any such kind of device? Any other ideas? Any help?
> 
>Any kind of information is greatly appreciated (hints, pointers, ideas, etc.)
> 
>--
>Volker Herminghaus-Shirai (vhs@rhein-main.de)

One system that I have discovered that may meet your needs is a system
that automates a library of 5.25" optical disks.  Their largest holds
2000 disks.  The factor that makes it applicable is that it can have
up to 100 drives per unit.  However, this unit can only have two
changers and it takes 5 seconds too exchange a disk.

With 1GB magneto-optical rewritable disks (2 GB disks expected by 
spring 93) you could get 2TB/system so you would need 5 systems.
Getting a computer system to handle 500 drives may be tough.

The company is Document Imaging Systems Corp.
               541 Weddell Dr.,
               Sunnyvale, CA., 94089
               tel. (408)734-5287

You have really tough requirements, but maybe if you have enough money
it could be done.

Phil Pease 
My witty disclaimer - everything I perceive, through either sensory or
extrasensory means, has been filtered to such an extent that you had better not
attempt to attribute anything I say to anyone else.