Date: Sat, 1 Apr 1995 14:32:46 -0800
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From: chuqui@netcom.com (Chuq Von Rospach)
To: Multiple recipients of list <apple-internet-announce@abs.apple.com>
Subject: ECRT Advisory - EA-95:01 Severe Bit Shortage
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Since this has significant impact to Internet services, I felt I should
pass this along as quickly as possible.

chuq
---


>Date: Sat, 1 Apr 1995 16:25:23 -0600
>From: ecrt-advisory@ecrt.org (ECRT Advisory) (by way of
>werner@cs.utexas.edu (Werner Uhrig))
>Subject: ECRT Advisory - EA-95:01 Severe Bit Shortage
>
>=============================================================================
>EA-95:01                        ECRT Advisory
>                                April 1, 1995
>                              Severe Bit Shortage
>-----------------------------------------------------------------------------
>
>This advisory supersedes all previous ECRT advisories on the bit-shortage
>problem.
>
>The Coordination Center of the Emergency Computer Response Team (ECRT) has
>received reports of a severe bit shortage affecting a range of computer
>systems.  The problem has been observed to occur to varying degrees in all
>computing platforms and operating systems.  In an extreme case, the shortage
>precipitated the complete shutdown of a local-area network (LAN) and all
>associated hosts.
>
>The ECRT staff recommends that you follow the emergency procedures described in
>section III until vendors are able to supply hardware and software updates to
>manage the problem.
>
>As we receive additional information relating to this advisory, we will place
>it, along with any clarifications, in a EA-95:05.README file. ECRT advisories
>and their associated README files are available by anonymous FTP from
>info.ecrt.org. We encourage you to check the README files regularly for updates
>on advisories that relate to your site.
>
>-----------------------------------------------------------------------------
>
>I.   Description
>
>A known but previously sporadic problem is in imminent danger of becoming
>widespread: Computer systems that are used intensively for software development
>or other demanding applications are vulnerable to exhausting their bit supply.
>While the storage elements that hold the systems bits are reused indefinitely,
>the bits themselves are often transferred to locations where they become
>effectively unrecoverable.  This occurs, for example, when the bits are written
>onto backup tapes, transmitted to a remote site through a network connection,
>or---worst of all---written to a display screen, from where they escape into
>the atmosphere.
>
>While programmers commonly consider the bit supply to be infinite, it is in
>fact a limited resource built into the hardware at the time of manufacture.  A
>hardware bit supply of 64K bits was first introduced by IBM in its System/360.
>This was immediately found to be inadequate, but remained in place for a number
>of years for compatibility reasons; a tragic design flaw that was echoed in the
>Intel x86 memory architecture, nearly two decades later.
>
>In UNIX systems the hardware bit supply, commonly called the "bit bucket," is
>accessible through the file system as the character-special file /dev/null.
>Vendors of UNIX-based workstations such as Sun Microsystems have moved quickly
>to meet the unanticipated demand for bits by offering to retrofit existing
>hardware with replenished, higher-capacity bit buckets.  Sun has also announced
>plans to spin off a new subsidiary, SunBits, that will reclaim unused bits from
>obsolete hardware.
>
>II.  Impact
>
>Users of systems whose bit buckets are nearly exhausted experience an inability
>to load or execute programs, or to display results on consoles or terminals.
>Network intruders who gain root privileges may also render a system
>inoperative by stealing the contents of the bit bucket for use on their own
>systems.
>
>III. Solution
>
>A.  To reduce the rate at which bits are lost, ECRT recommends that all display
>screens be turned off, and the output of all programs be redirected to
>/dev/null until vendor updates are obtained.
>
>B.  Where solution A is impractical, bits may be recycled into the bit bucket
>>from  unused software and data being stored on disk or other magnetic media.
>ECRT recommends files associated with Microsoft Windows 3.1 as a source of
>recyclable bits because of their low utility/bit ratio.
>
>C.  ECRT is advocating the installation of a high-bandwidth network link
>between North America and the country of Mauritius, where 90% of the world's
>raw bit supply is currently mined.  Donation of bit processing equipment by the
>goverment of Singapore, and of a file server by the United Nations, will soon
>allow bit-poor NFS-capable systems to mount the proposed file system
>bigbits.bitmine.mau:/bucket as /dev/null.
>

  Chuq Von Rospach <PlaidSoft: Writing, Editing, and Damage Control for Hire>
         chuqui@netcom.com * GEnie:chuq * AOL:chuqui * CIS:75141,1242
         chuq@abs.apple.com * Apple Business Systems * Software Gnome
            {Member Science Fiction & Fantasy Writers of America}
              Home page: http://abs.apple.com/~chuq/chuqui.html

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