Storage: Alternate Futures

1
Storage Alternate Futures
Yotta Zetta Exa Peta Tera Giga Mega Kilo

• Jim Gray
• Microsoft Research
• Research.Micrsoft.com/Gray/talks
• NetStore 99
• Seattle WA, 14 Oct 1999

2
Acknowledgments Thank You!!

• Dave Patterson
• Convinced me that processors are moving to the
  devices.
• Kim Keeton and Erik Riedell
• Showed that many useful subtasks can be done by
  disk-processors, and quantified execution
  interval
• Remzi Dusseau
• Re-validated Amdhls laws

3
Outline

• The Surprise-Free Future (5 years)
• 500 mips cpus for 10
• 1 Gb RAM chips
• MAD at 50 Gbpsi
• 10 GBps SANs are ubiquitous
• 1 GBps WANs are ubiquitous
• Some consequences
• Absurd (?) consequences.
• Auto-manage storage
• Raid10 replaces Raid5
• Disc-packs
• Disk is the archive media of choice
• A surprising future?
• Disks (and other useful things) become
  supercomputers.
• Apps run in the disk

4
The Surprise-free Storage Future

• 1 Gb RAM chips
• MAD at 50 Gbpsi
• Drives shrink one quantum
• Standard IO
• 10 GBps SANs are ubiquitous
• 1 Gbps WANs are ubiquitous
• 5 tips cpus for 1K and 500 mips cpus for 10

5
1 Gb RAM Chips

• Moving to 256 Mb chips now
• 1Gb will be standard in 5 years, 4 Gb will
  be premium product.
• Note
• 256Mb 32MB the smallest memory
• 1 Gb 128 MB the smallest memory

6
MAD at 50 Gbpsi

• MAD Magnetic Aerial Density
• 3-10 Mbpsi in products
• 20 Mbpsi in lab
• 50 Mbpsi paramagnetic limit
  but. People have ideas.
• Capacity rise 10x in 5 years (conservative)
• Bandwidth rise 4x in 5 years (densityrpm)
• Disk 50GB to 500 GB,
• 60-80MBps
• 1k/TB
• 15 minute to 3 hour scan time.

7
Disk vs Tape

• Disk
• 47 GB
• 15 MBps
• 10 ms seek time
• 5 ms rotate time
• 9/GB for drive 3/GB for ctlrs/cabinet
• 4 TB/rack

• Tape
• 40 GB
• 5 MBps
• 30 sec pick time
• Many minute seek time
• 5/GB for media10/GB for drivelibrary
• 10 TB/rack

Guestimates Cern 200 TB 3480 tapes 2 col
50GB Rack 1 TB 20 drives
The price advantage of tape is narrowing, and
the performance advantage of disk is growing
8
System On A Chip

• Integrate Processing with memory on one chip
• chip is 75 memory now
• 1MB cache gtgt 1960 supercomputers
• 256 Mb memory chip is 32 MB!
• IRAM, CRAM, PIM, projects abound
• Integrate Networking with processing on one chip
• system bus is a kind of network
• ATM, FiberChannel, Ethernet,.. Logic on chip.
• Direct IO (no intermediate bus)
• Functionally specialized cards shrink to a chip.

9
500 mips System On A Chip for 10

• 486 now 7 233 Mhz ARM for 10 system on a
  chiphttp//www.cirrus.com/news/products99/news-pr
  oduct14.html AMD/Celeron 266 30
• In 5 years, todays leading edge will be
• System on chip (cpu, cache, mem ctlr, multiple
  IO)
• Low cost
• Low-power
• Have integrated IO
• High end is 5 BIPS cpus

10
Standard IO in 5 Years

• Probably
• Replace PCI with something better will still
  need a mezzanine bus standard
• Multiple serial links directly from processor
• Fast (10 GBps/link) for a few meters
• System Area Networks (SANS) ubiquitous (VIA
  morphs to SIO?)

11
Ubiquitous 10 GBps SANs in 5 years

• 1Gbps Ethernet are reality now.
• Also FiberChannel ,MyriNet, GigaNet, ServerNet,,
  ATM,
• 10 Gbps x4 WDM deployed now (OC192)
• 3 Tbps WDM working in lab
• In 5 years, expect 10x, progress is astonishing
• Gilders law Bandwidth grows 3x/year
  http//www.forbes.com/asap/97/0407/090.htm

1 GBps
120 MBps (1Gbps)
80 MBps
5 MBps
40 MBps
20 Mbsp
12
Thin Clients mean HUGE servers

• AOL hosting customer pictures
• Hotmail allows 5 MB/user, 50 M users
• Web sites offer electronic vaulting for SOHO.
• IntelliMirror replicate client state on server
• Terminal server timesharing returns
• . Many more.

13
Standard Storage Metrics

• Capacity
• RAM MB and /MB today at 512MB and 3/MB
• Disk GB and /GB today at 50GB and 10/GB
• Tape TB and /TB today at 50GB and
  12k/TB (nearline)
• Access time (latency)
• RAM 100 ns
• Disk 10 ms
• Tape 30 second pick, 30 second position
• Transfer rate
• RAM 1 GB/s
• Disk 15 MB/s - - - Arrays can go to 1GB/s
• Tape 5 MB/s - - - striping is
  problematic, but works

14
New Storage Metrics Kaps, Maps, SCAN?

• Kaps How many kilobyte objects served per second
• The file server, transaction processing metric
• This is the OLD metric.
• Maps How many megabyte objects served per second
• The Multi-Media metric
• SCAN How long to scan all the data
• the data mining and utility metric
• And
• Kaps/, Maps/, TBscan/

15
For the Record (good 1999 devices packaged in
systemhttp//www.tpc.org/results/individual_resul
ts/Compaq/compaq.5500.99050701.es.pdf)
X 100
Tape is 1Tb with 4 DLT readers at 5MBps each.
16
For the Record (good 1999 devices packaged in
systemhttp//www.tpc.org/results/individual_resul
ts/Compaq/compaq.5500.99050701.es.pdf)
Tape is 1Tb with 4 DLT readers at 5MBps each.
17
The Access Time Myth

• The Myth seek or pick time dominates
• The reality (1) Queuing dominates
• (2) Transfer dominates BLOBs
• (3) Disk seeks often short
• Implication many cheap servers better than
  one fast expensive server
• shorter queues
• parallel transfer
• lower cost/access and cost/byte
• This is obvious for disk arrays
• This even more obvious for tape arrays

Wait
Transfer
Transfer
Rotate
Rotate
Seek
Seek
18
Storage Ratios Changed

• DRAM/disk media price ratio changed
• 1970-1990 1001
• 1990-1995 101
• 1995-1997 501
• today 0.1pMB disk 301
  3pMB dram

• 10x better access time
• 10x more bandwidth
• 4,000x lower media price

19
Data on Disk Can Move to RAM in 8 years
301
6 years
20
Outline

• The Surprise-Free Future (5 years)
• 500 mips cpus for 10
• 1 Gb RAM chips
• MAD at 50 Gbpsi
• 10 GBps SANs are ubiquitous
• 1 GBps WANs are ubiquitous
• Some consequences
• Absurd (?) consequences.
• Auto-manage storage
• Raid10 replaces Raid5
• Disc-packs
• Disk is the archive media of choice
• A surprising future?
• Disks (and other useful things) become
  supercomputers.
• Apps run in the disk.

21
The (absurd?) consequences

• 256 way nUMA?
• Huge main memories now 500MB - 64GB memories
  then 10GB - 1TB memories
• Huge disksnow 5-50 GB 3.5 disks then 50-500
  GB disks
• Petabyte storage farms
• (that you cant back up or restore).
• Disks gtgt tapes
• Small disksOne platter one inch 10GB
• SAN convergence 1 GBps point to point is easy

• 1 GB RAM chips
• MAD at 50 Gbpsi
• Drives shrink one quantum
• 10 GBps SANs are ubiquitous
• 500 mips cpus for 10
• 5 bips cpus at high end

22
The Absurd? Consequences

• Further segregate processing from storage
• Poor locality
• Much useless data movement
• Amdahls laws bus 10 B/ips io 1 b/ips

Disks
Processors
100 GBps
10 TBps
1 Tips
100TB
23
Storage Latency How Far Away is the Data?
Andromeda
9
Tape /Optical
10
2,000 Years
Robot
6
Pluto
Disk
2 Years
10
1.5 hr
Olympia
Memory
100
This Hotel
10
10 min
On Board Cache
On Chip Cache
2
This Room
Registers
1
My Head
1 min
24
Consequences

• AutoManage Storage
• Sixpacks (for arm-limited apps)
• Raid5-gt Raid10
• Disk-to-disk backup
• Smart disks

25
Auto Manage Storage

• 1980 rule of thumb
• A DataAdmin per 10GB, SysAdmin per mips
• 2000 rule of thumb
• A DataAdmin per 5TB
• SysAdmin per 100 clones (varies with app).
• Problem
• 5TB is 60k today, 10k in a few years.
• Admin cost gtgt storage cost???
• Challenge
• Automate ALL storage admin tasks

26
The Absurd Disk

• 2.5 hr scan time (poor sequential access)
• 1 aps / 5 GB (VERY cold data)
• Its a tape!

1 TB
100 MB/s
200 Kaps
27
Extreme case 1TB disk Alternatives

• Use all the heads in parallel
• Scan in 30 minutes
• Still one Kaps/5GB
• Use one platter per arm
• Share power/sheetmetal
• Scan in 30 minutes
• One KAPS per GB

500 MB/s
1 TB
200 Kaps
500 MB/s
200GB each
1,000 Kaps
28
Drives shrink (1.8, 1)

• 150 kaps for 500 GB is VERY cold data
• 3 GB/platter today, 30 GB/platter in 5years.
• Most disks are ½ full
• TPC benchmarks use 9GB drives (need arms or
  bandwidth).
• One solution smaller form factor
• More arms per GB
• More arms per rack
• More arms per Watt

29
Prediction 6-packs

• One way or another, when disks get huge
• Will be packaged as multiple arms
• Parallel heads gives bandwidth
• Independent arms gives bandwidth aps
• Package shares power, package, interfaces

30
Stripes, Mirrors, Parity (RAID 0,1, 5)

• RAID 0 Stripes
• bandwidth
• RAID 1 Mirrors, Shadows,
• Fault tolerance
• Reads faster, writes 2x slower
• RAID 5 Parity
• Fault tolerance
• Reads faster
• Writes 4x or 6x slower.

0,3,6,..
1,4,7,..
2,5,8,..
0,1,2,..
0,1,2,..
0,2,P2,..
1,P1,4,..
P0,3,5,..
31
RAID 10 (strips of mirrors) Winswastes space,
saves arms

• RAID 5
• Performance
• 225 reads/sec
• 70 writes/sec
• Write
• 4 logical IO,
• 2 seek 1.7 rotate
• SAVES SPACE
• Performance degrades on failure

• RAID1
• Performance
• 250 reads/sec
• 100 writes/sec
• Write
• 2 logical IO
• 2 seek 0.7 rotate
• SAVES ARMS
• Performance improves on failure

32
The Storage RackToday

• 140 arms
• 4TB
• 24 racks24 storage processors61 in rack
• Disks 2.5 GBps IO
• Controllers 1.2 GBps IO
• Ports 500 MBps IO

33
Storage Rack in 5 years?

• 140 arms
• 50TB
• 24 racks24 storage processors61 in rack
• Disks 2.5 GBps IO
• Controllers 1.2 GBps IO
• Ports 500 MBps IO
• My suggestion move the processors into the
  storage racks.

34
Its hard to archive a PetaByteIt takes a LONG
time to restore it.

• Store it in two (or more) places online (on
  disk?).
• Scrub it continuously (look for errors)
• On failure, refresh lost copy from safe copy.
• Can organize the two copies differently
  (e.g. one by time, one by space)

35
Crazy Disk Ideas

• Disk Farm on a card surface mount disks
• Disk (magnetic store) on a chip (micro machines
  in Silicon)
• Full Apps (e.g. SAP, Exchange/Notes,..) in the
  disk controller (a processor with 128 MB dram)

ASIC
The Innovator's Dilemma When New Technologies
Cause Great Firms to FailClayton M.
Christensen.ISBN 0875845851
36
The Disk Farm On a Card

• The 500GB disc card
• An array of discs
• Can be used as
• 100 discs
• 1 striped disc
• 50 Fault Tolerant discs
• ....etc
• LOTS of accesses/second
• bandwidth

14"
37
Functionally Specialized Cards
P mips processor

• Storage
• Network
• Display

Today P50 mips M 2 MB
M MB DRAM
In a few years P 200 mips M 64 MB
ASIC
ASIC
38
Its Already True of PrintersPeripheral
CyberBrick

• You buy a printer
• You get a
• several network interfaces
• A Postscript engine
• cpu,
• memory,
• software,
• a spooler (soon)
• and a print engine.

39
All Device Controllers will be Cray 1s

• TODAY
• Disk controller is 10 mips risc engine with 2MB
  DRAM
• NIC is similar power
• SOON
• Will become 100 mips systems with 100 MB DRAM.
• They are nodes in a federation (can run Oracle
  on NT in disk controller).
• Advantages
• Uniform programming model
• Great tools
• Security
• Economics (cyberbricks)
• Move computation to data (minimize traffic)

Central Processor Memory
Tera Byte Backplane
40
With Tera Byte Interconnectand Super Computer
Adapters

• Processing is incidental to
• Networking
• Storage
• UI
• Disk Controller/NIC is
• faster than device
• close to device
• Can borrow device package power
• So use idle capacity for computation.
• Run app in device.
• Both Kim Keeton (UCB) and Erik Riedel (CMU)
  thesis investigate thisshow benefits of this
  approach.

41
Implications
Conventional
Radical

• Move app to NIC/device controller
• higher-higher level protocols CORBA / COM.
• Cluster parallelism is VERY important.

• Offload device handling to NIC/HBA
• higher level protocols I2O, NASD, VIA, IP, TCP
• SMP and Cluster parallelism is important.

42
How Do They Talk to Each Other?

• Each node has an OS
• Each node has local resources A federation.
• Each node does not completely trust the others.
• Nodes use RPC to talk to each other
• CORBA? COM? RMI?
• One or all of the above.
• Huge leverage in high-level interfaces.
• Same old distributed system story.

Applications
Applications
datagrams
datagrams
streams
RPC
?
streams
RPC
?
SIO
SIO
SAN
43
Outline

• The Surprise-Free Future (5 years)
• Astonishing hardware progress.
• Some consequences
• Absurd (?) consequences.
• Auto-manage storage
• Raid10 replaces Raid5
• Disc-packs
• Disk is the archive media of choice
• A surprising future?
• Disks (and other useful things) become
  supercomputers.
• Apps run in the disk