The Solid State Storage Revolu1on. Andy Bechtolsheim Sun Microsystems

Transcription

1 The Solid State Storage Revolu1on Andy Bechtolsheim Sun Microsystems

2 A Quick History of the Hard Disk 1956: IBM introduces 350 Storage Unit, first Hard disk (5 MB) 1962: IBM introduces Model 1301 Advanced Disk File (25 MB) 1970: IBM introduces Model 3330 DAS Disk Drive (100 MB) 1980: IBM introduces Model 3380 DAS Disk Drive (2500 MB) 2002: IBM sells its disk business to Hitachi 2004: RPM Disks store 250 GB (250,000 MB) 2006: 50 Year Anniversary of the Hard disk drive 2008: RPM Disks store 1 TB (1,000,000 MB)

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6 Hard Disk $/GB Cost Evolu1on $/GB TIme

7 IOPS Per Hard Disk RPM 10K RPM 15K RPM 125 IOPS 180 IOPS 250 IOPS

8 Hard Disk Evolu1on Great improvements in: Density (average 60% / year growth) Cost per GB (tracking density) Some improvements in: Transfer rate (higher bit density) Interface speed (SAS SATA I/II/III) No significant improvements in: IOPS per disk (more or less same) Reliability per disk (more or less same)

9 Hard Disk Summary HDD have made enormous improvements in capacity, cost per GB and reliability per GB Very limited improvements in performance IOPS per GB are con1nuously declining In the meanwhile, server performance is increasing at 50 60% per year, leading to a major CPU versus I/O performance crisis

10 In the meanwhile

11 A New Development: Flash Memory 1985: Toshiba shows first Flash chip (256 Kbit) 1995: First Mul1 level Flash chip (32 Mbit) 2002: Samsung delivers 1 Gbit chips (120 nm) 2005: Samsung delivers 4 Gbit chips (70 nm) 2006: Flash Market hits $12B in revenue 2008: Toshiba delivers 16 Gbit chips (56 nm)

12 A 16 Gbit Flash Chip

13 Gartner Flash Forecast (Aug 2008)

14 The NAND Flash Price Free Fall

15 SLC and MLC FLash SLC: Single level Flash: 1 Bit / T Most Robust Flash Technology > 500,000 Write Cycles Ideal for enterprise applica1ons MLC: Mul1 level Flash: Bits/T Most Cost effec1ve Flash Technology > 10,000 Write Cycles Ideal for consumer applica1ons

16 Flash Reliability SLC is the most reliable 5 Year Life cycles with con1nuous writes Gradual capacity reduc1on over 1me No mechanical failure modes MLC does not do a lot of writes Even with RAID device does not last Only usable in read mostly applica1ons There are some of these in enterprise

17 Flash Performance Random Read Access Time: 100 us (10K IOPS) This is per device or device channel Typical controller has 4 channels Typical controller read performance is 30K IOPS Write cycles are considerably slower Erase cycles are painfully slow Controller hides these with erase ahead Typical controller write performance is 10K IOPS

18 Flash Performance Roadmap New Enterprise Flash device category Higher reliability Higher throughput Lower access 1mes Next genera1on Flash Controllers Faster I/O Interfaces, more channels Faster CPU clock rates Larger DRAM Caches

19 Role of Flash Memory Controller FMC is Key for Reliability and Performance Func1ons of FMC: Error correc1on Wear leveling Bad Block mapping Scrubbing Write caching Read caching Significant Improvements Ahead

20 Typical Flash Memory Controller Flash Flash Flash Flash ucode FMC DRAM SAS/SATA Interface

21 Flash vs Disk Performance Flash is more than 100X faster than disk Flash consumes less power than hard disk Flash is more reliable than hard disk Flash is physically smaller than hard disk Flash is a lot cheaper per IOPS than Disk Disk is a lot cheaper per GB than Flash

22 Flash as a Disk Cache Flash as a Cache is a very promising Model Most stored data is not ac1vely being accessed Working set is typically a few % of total capacity Caching the ac1vely used data in Flash makes the en1re disk storage appear as fast as Flash Significant gain for I/O intensive workloads Key is to not have to change the applica1on

23 Flash Cache in Solaris ZFS ZFS already supports a DRAM memory cache Cache efficiency is limited to size of main memory Trivial to extend mem cache to FLASH Flash can be much larger than main memory Flash cache divided into two segments: Readzilla for Read Caching Logzilla for Transac1onal Commits Delivers significant cost performance gains

24 ZFS Hybrid Pool Example

25 Sun Project Lightning Flash What is the speed limit with Flash? Are mul1 million IOPS achievable? What storage fabrics can support this? How much space/power/cooling will this take?

26 Lightning Flash First Results Speed limit is HBAs, not Flash HBAs were not designed for Flash I/O rates One million IOPS achievable today Requires lots of PCI slots and HBAs Exis1ng HDD arrays are problema1c for SSDs There are simply not enough I/O channels SSDs significantly improve IOPS power efficiency Almost a factor of 100X compared to hard disk

27 Other Flash Use Models Use Flash as boot device No brainer, just a ques1on of cost Saves space and power Make Flash part of the memory hierarchy Unfortunately this is not applica1on transparent Flash is ~ 1000X slower than DRAM Replace exis1ng disk access protocols Memory transfers more efficient than SCSI Will be required to scale to Mul1 million IOPS

28 Gartner HDD and Flash Forecast

29 In Conclusion Flash is ~ 100X faster than Hard disks Flash is ~ 100X more IOPS power efficient Flash prices are dropping about 50% / year This makes Flash suddenly very interes1ng Using Flash as cache looks very promising Flash Cost of Hard Disk Hard Disks are not going away any1me soon