Meta-Message: Technology Ratios Matter

1
Meta-Message Technology Ratios Matter

• Price and Performance change.
• If everything changes in the same way, then
  nothing really changes.
• If some things get much cheaper/faster than
  others, then that is real change.
• Some things are not changing much
• Cost of people
• Speed of light
• And some things are changing a LOT

2
Trends Moores Law

• Performance/Price doubles every 18 months
• 100x per decade
• Progress in next 18 months ALL previous
  progress
• New storage sum of all old storage (ever)
• New processing sum of all old processing.
• E. coli double ever 20 minutes!

15 years ago
3
Trends ops/s/ Had Three Growth Phases

• 1890-1945
• Mechanical
• Relay
• 7-year doubling
• 1945-1985
• Tube, transistor,..
• 2.3 year doubling
• 1985-2000
• Microprocessor
• 1.0 year doubling

4
Trends Gilders Law 3x bandwidth/year for 25
more years

• Today
• 40 Gbps per channel (?)
• 12 channels per fiber (wdm) 500 Gbps
• 32 fibers/bundle 16 Tbps/bundle
• In lab 3 Tbps/fiber (400 x WDM)
• In theory 25 Tbps per fiber
• 1 Tbps USA 1996 WAN bisection bandwidth
• Aggregate bandwidth doubles every 8 months!

1 fiber 25 Tbps
5
How much does wire-time cost?/Mbyte?

• Cost Time
• Gbps Ethernet .2µ 10 ms
• 100 Mbps Ethernet .3µ 100 ms
• OC12 (650 Mbps) .003 20 ms
• DSL .0006 25 sec
• POTs .002 200 sec
• Wireless .80 500 sec

6
Data delivery costs 1/GB toady

• Rent for big customers 300/megabit per
  second per month
• Improved 3x in last 6 years (!).
• That translates to 1/GB you send.
• You can mail a 160 GB disk for 20.
• Thats 16x cheaper
• If overnight its 3 MBps.

3x160 GB ½ TB
7
Trends Magnetic Storage Densities

• Amazing progress
• Ratios have changed
• Capacity grows 60/y
• Access speed grows 10x more slowly

8
Storage Hierarchy Speed Capacity vs Cost
Tradeoffs
Price vs Speed
Size vs Speed
Nearline
Cache
Tape
Offline
Main
Tape
Disc
Secondary
Online
Online
Secondary
/MB
Tape
Tape
Disc
Typical System (bytes)
Main
Offline
Nearline
Tape
Tape
Cache
-9
-6
-3
0
3
-9
-6
-3
0
3
10
10
10
10
10
10
10
10
10
10
Access Time (seconds)
Access Time (seconds)
9
Storage Ratios Changed

• 10x better access time
• 10x more bandwidth
• 100x more capacity
• Data 25x cooler (1Kaps/20MB vs 1Kaps/500MB)
• 4,000x lower media price
• 20x to 100x lower disk price
• Scan takes 10x longer (3 min vs 45 min)

• DRAM/disk media price ratio changed
• 1970-1990 1001
• 1990-1995 101
• 1995-1997 501
• today 6/GB disk 1001
  600/GB dram

10
Data on Disk Can Move to RAM in 10 years
1001
10 years
11
The Five Minute Rule

• Trade DRAM for Disk Accesses
• Cost of an access (Drive_Cost /
  Access_per_second)
• Cost of a DRAM page ( /MB/ pages_per_MB)
• Break even has two terms
• Technology term and an Economic term
• Grew page size to compensate for changing ratios.
• Now at 5 minutes for random, 10 seconds sequential

12
The 5 Minute Rule Derived

Disk Access Cost /T DiskPrice .
AccessesPerSecond
( )/T
Cost a RAM Page RAM__Per_MB
PagesPerMB

T TimeBetweenReferences to Page

• Breakeven
• RAM__Per_MB _____DiskPrice
  .
• PagesPerMB T x
  AccessesPerSecond

• T DiskPrice x
  PagesPerMB .
• RAM__Per_MB x
  AccessPerSecond

13
Plugging in the Numbers
PPM/aps disk/Ram Break Even
Random 128/120 1 1000/3 300 5 minutes
Sequential 1/30 .03 300 10seconds

• Trend is longer times because disk not
  changing much, RAM declining 100x/decade

5 Minutes 10 second rule
14
Summarizing storage rules of thumb (1)

• Moores law 4x every 3 years 100x more per
  decade
• Implies 2 bit of addressing every 3 years.
• Storage capacities increase 100x/decade
• Storage costs drop 100x per decade
• Storage throughput increases 10x/decade
• Data cools 10x/decade
• Disk page sizes increase 5x per decade.

15
Summarizing storage rules of thumb (2)

• RAMDisk and DiskTape cost ratios are 1001
  and 31
• So, in 10 years, disk data can move to RAM since
  prices decline 100x per decade.
• A person can administer a million dollars of disk
  storage that is 1TB - 100TB today
• Disks are replacing tapes as backup devices.You
  cant backup/restore a Petabyte quicklyso
  geoplex it.
• Mirroring rather than Parity to save disk arms

16
Meta-Message Technology Ratios Matter

• Price and Performance change.
• If everything changes in the same way, then
  nothing really changes.
• If some things get much cheaper/faster than
  others, then that is real change.
• Some things are not changing much
• Cost of people
• Speed of light
• And some things are changing a LOT