Re: How to calculate a useful size for a given pool

From: Brian Evans (b..evans_at_sympatico.ca)
Date: 08/04/04 

Date: Wed, 4 Aug 2004 09:21:01 -0400

"Gareth Williams" <gareth@nospam.com> wrote in message
news:pan.2004.08.02.22.38.28.892434@nospam.com...
> On Mon, 02 Aug 2004 15:44:27 -0400, Brian Evans wrote:
>
>>> 1. A firm receives 100,000 orders per week as electronic documents.
> <snip>
>>> 4. Retrieval from CDROM is time-consuming but a limited amount of space
>>> is
>>> available to cache some of the documents on networked storage for more
>>> immediate retrieval. There is not enough space to cache all the
>>> documents
>>> so the older cached documents are deleted regularly.
> <snip>
>> #4 mostly likely doesn't hold true anymore.
>> Hardrives have increased in capacity making caching all the data easy. A
>> single 250gb drive caches 384 CDs worth at 650mb per CD. A fully
>> decked out $10,999 Apple XServe RAID would cache 5384 CDs.
>> Thats 35/mb of electronic documents per order if 100,000 are
>> stored on the XServer at any one time.
>
> I was simplifying the figures for illustrative purposes - in reality,
> the volume is very much bigger. Sure, we could throw lots of storage at
> the issue, but I am grappling with the problem of what would be the most
> sensible amount of storage without having to cache everything for an
> over-long period of time. Having said that, a rough calculation shows that
> an XServe would hold over 100 days' worth of documents, which may be quite
> adequate. I just want to make sure, though. Thanks for the Apple tip, by
> the way - sounds a steal at that price.

Another thing to consider is the format of the documents in the cache. Using
Adobe Acrobat (not the free reader - the full program) bitmapped scans
can be converted to postscript PDFs including OCRing of text. This can
make the documents take orders of magnitude less space. Easily 100
to 1 vs straight 300dpi bitmaps.

Brian Evans