Slide 1 Technology Changes Mid1980s 2012 Change CPU speed 15 MHz 25 GHz 167x Memory size 8 MB 4 GB 500x Disk capacity 30 MB 500 GB 16667x Disk transfer rate 2 MBs 100 MBs ID: 356196
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Slide1
CS 140 Lecture Notes: Technology and Operating Systems
Slide 1
Technology Changes
Mid-1980’s
2012
Change
CPU speed
15 MHz
2.5 GHz
167x
Memory size
8 MB
4 GB
500x
Disk capacity
30 MB
500 GB
16667x
Disk transfer rate
2 MB/s
100 MB/s
50x
Network speed
10 Mb/s
1 Gb/s
100xSlide2
Can’t afford to page out unless idle for a long time
CS 140 Lecture Notes: Technology and Operating Systems
Slide
2
Role of Paging
1960’s
Today
Change
Disk latency
80
ms
10
ms
8x
Disk transfer rate
250 KB/s
100 MB/s
400x
Memory size
256 KB
4 GB
16000x
Time to replace all of memory (random)
6.4 s
3 hours
1500x
Time to replace all of memory (sequential)
1 s
40 s
40xSlide3
DRAM in Storage Systems
Usage exploding, but:
Clumsy (consistency with backing store)
Lost performance
(cache misses, backing store)
CS 140 Lecture Notes: Technology and Operating Systems
Slide
3
1970
1980
1990
2000
2010
UNIX buffer
cache
Main-memory
databases
Large file
caches
Web indexes
entirely in DRAM
memcached
Facebook:
200 TB total data
150 TB cache!
Main-memory
DBs, againSlide4
General-purpose storage in DRAM:
All data always in DRAM (no cache misses)As durable and available as diskDesigned for datacenters:
Scale: 1000+ servers, 100+ TBLow latency
: 5-10µs remote access
Potential impact:
enable new class of applications
CS 140 Lecture Notes: Technology and Operating Systems
Slide
4
RAMCloudSlide5
CS 140 Lecture Notes: Technology and Operating Systems
Slide
5
RAMCloud Architecture
Master
Backup
Master
Backup
Master
Backup
Master
Backup
…
Appl.
Library
Appl.
Library
Appl.
Library
Appl.
Library
…
Datacenter
Network
Coordinator
1000 – 10,000 Storage Servers
1000 – 100,000 Application Servers
Commodity
Servers
64-256 GB
per server
High-speed networking:
5 µs round-trip
Full bisection
bwidthSlide6
create(
tableId
, blob)
=>
objectId
, version
read(
tableId
,
objectId
)
=> blob, version
write(tableId,
objectId, blob)
=> version
cwrite(tableId
, objectId
, blob, version)
=> version
delete(tableId
, objectId
)
CS 140 Lecture Notes: Technology and Operating SystemsSlide 6
Data Model: Key-Value StoreTables
Identifier (64b)
Version (64b)
Blob (≤1MB)
Object
(Only overwrite if
version matches)
Richer model in the future:
Indexes?
Transactions?
Graphs?Slide7
CS 140 Lecture Notes: Technology and Operating Systems
Slide
7
Research Issues
Durability and availability
Fast communication (RPC)
Data model
Concurrency, consistency, transactions
Data distribution, scaling
Multi-tenancy
Client-server functional distribution
Node architectureSlide8
CS 140 Lecture Notes: Technology and Operating Systems
Slide 8