UC Berkeley 1 The Datacenter is the Computer David Patterson Director, RAD Lab January, 2007

2 Technology Trends: CPU Microprocessor: Power Wall + Memory Wall + ILP Wall = Brick Wall  End of uniprocessors and faster clock rates Since parallel more power efficient (W ≈ CV 2 F) New “Moore’s Law” is 2X processors or “cores” per socket every 2 years, same clock frequency –Conservative: cores, cores, cores for embedded, desktop, & server –Sea change for HW and SW industries since changing programmer model, responsibilities  Every program(mer) is a parallel program(mer), Sequential algorithms are slow algorithms

3 Technology Trends: DRAM DRAM capacity: decelerate capacity per chip due in part to 32-bit address limit, investments –512 Mbit sold in 2002; still dominates (1 GB DIMM) –2X capacity every 3 years? (vs. 4X/3yrs in 1990s) –DRAM performance: only BW improvements (DDR-2, DDR-3), little latency improvement 64-bit Addresses + Multiple cores/socket  Majority number of chips DRAM vs. Logic  Majority % of system cost DRAM vs. Logic  Majority % of power is DRAM vs. Logic Shift in % chips, cost, power to DRAM from CPU increases over time

4 Technology Trends: Disk Disk: After capacity 100% per year ‘96 - ‘03, slowdown to 30% per year recently (1TB in 07) –Consolidation of industry, lack of demand by PCs –Home Video restart PC demand, capacity wars? Split: ATA best $/GB, SCSI best $/performance Performance: Interface switch from parallel to serial: Serial ATA (SATA), Serial SCSI (SAS)  Low Cost Disk arrays Disk performance: latency slow change, bandwidth improves, but not as fast as capacity  Takes longer to read whole disk (3 hours)  Takes longer repair  Must handle 2 faults  RAID, as 3X too expensive in cost (& power)?

5 Technology Trends: Flash Flash Memory is credible threat to small disks –Modular, 1000X latency, ≈ BW, < power, but 1M writes Camera, Ipod industry funds flash R&D –Flash Improvement Rate: 2X GB/$ every 9 months? –IF disk and flash rates continue, flash matches GB/$ SCSI in 2009, GB/$ SATA in 2012 Future: Phase-change RAM (PRAM); no write limit, write 30X faster, archival; Samsung 2008? 2007SATASCSIFlashDRAM GB/$ IOPS/GB ,000,000 GB/Watt

6 Technology Trends: LAN Ethernet: from shared media to switch and twisted pair shortens time to new generation –But shorter distance per link over copper Year of Standard Mbit/s IEEE Mbit/s IEEE 802.3u Mbit/s IEEE 802.3ab Mbit/s IEEE 802.3ac (optical) Mbit/s IEEE 802.3an (copper) Expect 10 Gbit/s economical in Gbit/sec IEEE standard started 2006 –Standard in 2008? Economical in 2012?

7 Technology Trends: Internet Datacenters: new Internet backbone –Huge concentration of bandwidth & computation –Shift in traffic pattern More and more traffic is host  Datacenter Huge data transfers between/within DCs are the norm Note: IP alone not designed for such networks

8 Technology Trends: OS Resurgence of popularity in virtual machines –Traditional OSes too large and brittle –VM monitor thin SW layer btw guest OS and HW Advantages –Security, Dependability via isolation –VMs move from failing processor Rosenblum*: future of OS’s could be libraries where only functions needed linked into app, on top of thin VMM layer provides protection, sharing of resources –SW shipped with OS features + VM “reader”? * “The Impact of Virtualization on Computer Architecture and Operating Systems,” Keynote Address, ASPLOS XII, Oct. 23, 2006