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: Moore’s 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 Mechanical Relay 7-year doubling Tube, transistor, year doubling Microprocessor 1.0 year doubling

4 Trends: Gilder’s Law: 3x bandwidth/year for 25 more years Today: 40 Gbps per channel (λ) 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? $/Mbyte? CostTime Gbps Ethernet.2µ$ 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$/GB you send. You can mail a 160 GB disk for 20$. That’s 16x cheaper If overnight it’s 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 Typical System (bytes) Size vs Speed Access Time (seconds) Cache Main Secondary Disc Nearline Tape Offline Tape Online Tape $/MB Price vs Speed Access Time (seconds) Cache Main Secondary Disc Nearline Tape Offline Tape Online Tape

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 : : :1 today ~ 6$/GB disk 100:1 600$/GB dram

10 Data on Disk Can Move to RAM in 10 years 100:1 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 Cost a RAM Page RAM_$_Per_MB PagesPerMB The 5 Minute Rule Derived Breakeven: RAM_$_Per_MB = _____ DiskPrice. PagesPerMB T x AccessesPerSecond T = DiskPrice x PagesPerMB. RAM_$_Per_MB x AccessPerSecond $ ( ) /T T =TimeBetweenReferences to Page Disk Access Cost /T DiskPrice. AccessesPerSecond

13 Plugging in the Numbers PPM/aps disk$/Ram$ Break Even Random 128/120 ~1 1000/3 ~300 5 minutes Sequential 1/30 ~.03 ~ seconds 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) Moore’s 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) RAM:Disk and Disk:Tape cost ratios are 100:1 and 3:1 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 can’t backup/restore a Petabyte quickly so 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