The following is a summary to my posting a few weeks back regarding 8mm versus

4mm tape storage devices. This summary is intended to be a general overview

of the comments I received.

Tape Drive Costs

----------------

   8mm $3630

   4mm $1650 (less than half the price of the 8mm)

   * 4mm drives are in general much cheaper than 8mm drives. The above

     numbers are real quotes for Sun tape drives.

     8mm drives are more expensive likely due to the fact that all 8mm drives

     are licensed by Exabyte. Therefore, resellers have to pay royalties

     which push up the cost of the drives. 4mm is an open specification

     which forces competition among other things but the net result is the

     same, better prices.

Media Costs

-----------

   8mm $16 (112m data grade)

   4mm $27 (120m data grade)

   * 8mm tapes are almost half the cost of 4mm tapes. We use Sony P6-120MP

     video grade tapes which we buy for $8 (CDN). We have had problems in

     the past with some of the tapes but in general they have been very

     reliable. The above tape prices where taking from the INMAC (March 94)

     catalogue.

Cost per Megabyte

-----------------

   If we crunch the drive and media costs to find where the breakover point

   is we'll find that if you plan to use a large number of tapes, more than

   180, then its more cost effective to use 8mm. If you plan to user less

   than 180 tapes then 4mm drives are more cost effective. See below.

   Breakover Point:

      The breakover point is the point where the cost of buying 4mm and 8mm

      drives and media are the same.

        1650 + 27x = 3630 + 16x

               11x = 1980

                 x = 180 tapes

Format

------

   Both 8mm and 4mm drives use heilcal scan technology.

Reliability

-----------

   Judging by the ten or so responses I received most users feel that 4mm

   drives seem to be more reliable than 8mm ones. This isn't a large enough

   sample to make a real conclusion but I included it anyway. We have two

   2.3GB 8mm drives and one of them only works when it wants to.

Which one is faster

-------------------

   The only real concensus on this one is that 4mm drives seek much

   faster than 8mm drives.

Protecting your investment

--------------------------

   One important issue is compatibility with your network environment. If

   you have a large install base of 8mm drives it may make more sense to

   continue with 8mm. On the other hand, if you don't have either a 4mm

   or 8mm drive then read on.

Longevity

---------

   It is really hard to predict how long computer hardware and peripherals

   will last in this day and age but most people felt that 4mm and 8mm

   technologies will be around for a few more years yet.

Conclusions

-----------

   Both 4mm and 8mm are viable solutions for magnetic media backups and

   both solutions are likely be around for a number of years.

   

   If you have a large install base of one or the other then you should take

   that into consideration when making a final decision. If you don't have

   a 4mm or 8mm drive but you would like to buy one then from what I can

   tell, most people would choose the 4mm. This is especially true if you

   only plan to use a small quantity of tapes (150-200).

   The general feeling was that if users had to go out and purchase either

   a 4mm or 8mm drive, most people would choose the 4mm.

   Given all the above information we have decided to purchase a 4mm

   DAT drive.

My appreciation to all those who responded!

Regards,

Gary Braida | Canadian | ****** ******* ******

email: braida@cmc.ca | Microelectronics | * * * * *

phone: (613) 545-2914 | Corporation | ****** * * ******