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NEXPRe. S WP 8 Provisioning High-Bandwidth, High-Capacity Networked Storage on Demand Ari Mujunen Board NEXPRe. S WP 8 Provisioning High-Bandwidth, High-Capacity Networked Storage on Demand Ari Mujunen Board Meeting 20 -Sep-2010 in Manchester Research leading to these results has received funding from the European Union Seventh Framework Programme (FP 7/2007 - 2013) under grant agreement n° RI 261525. This presentation reflects only the author's views. The European Union is not liable for any use that may be made of the information contained therein.

WP 8 – High-bw+cap Storage on Demand Participants JIVE, ASTRON, INAF, UMAN, OSO, PSNC, WP 8 – High-bw+cap Storage on Demand Participants JIVE, ASTRON, INAF, UMAN, OSO, PSNC, AALTO Total person-months 163. 2 Deliverables 12 (11 reports and one demonstration test) 2 (17)

WP 8 – GANTT Chart with % of 1 FTE over Task Durations 3 WP 8 – GANTT Chart with % of 1 FTE over Task Durations 3 (17)

Partner Focus Areas AALTO Coordination, basic technologies ASTRON Long-term archival & reprocessing INAF Global/local Partner Focus Areas AALTO Coordination, basic technologies ASTRON Long-term archival & reprocessing INAF Global/local allocation/deallocation schemes JIVE Augmenting correlation capabilities /w buffering OSO Trial-site performance & applicability testing PSNC Role & trials of computing center buffering UMAN Trial-site performance & applicability testing 4 (17)

Start at Partners, First Deliverables AALTO Jul-2010. . Dec-2010 (D 8. 1), . . Start at Partners, First Deliverables AALTO Jul-2010. . Dec-2010 (D 8. 1), . . Feb-2011 (D 8. 2), . . ASTRON Jul-2010/Oct-2011. . Mar-2013 (D 8. 9) INAF Jul-2010. . Apr-2011 (D 8. 3), . . May-2012 (D 8. 6) JIVE Jul-2010. . Aug-2012 (D 8. 8), . . Feb-2013 (D 8. 10) OSO Feb-2011. . Sep-2012 (in D 8. 4), . . Mar-2013 (in D 8. 5+7) PSNC Feb-2011. . Sep-2012 (in D 8. 4), . . Mar-2013 (in D 8. 5+7) UMAN Feb-2011. . Sep-2012 (in D 8. 4), . . Mar-2013 (in D 8. 5+7) ACTION: Send your POC's email to 'Ari. [email protected] fi' for WP 8 deliverables and execution of work! 5 (17)

Objective • Determine the best practical mix of solutions – What kind of storage Objective • Determine the best practical mix of solutions – What kind of storage • HDDs, SSDs, memory buffers, others – Where located & packaged • Geographically (stations, correlators, computing centers, clouds, . . . ) • Locally (enclosures, racks, packaging, net topologies, . . . ) – Connected in which ways • Locally (interface types, net equipment, . . . ), globally (ship, net, LP, . . . ) – How storage is allocated/deallocated and accessed • Algorithms, APIs, sw structure; strategies to bookkeeping, . . . • Which will serve the needs of evolving (>1 Gbps) VLBI data acquisition and processing 6 (17)

Model / Mindset Framework • VLBI is globally geographically distributed data acquisition, data storage, Model / Mindset Framework • VLBI is globally geographically distributed data acquisition, data storage, and data processing – Where data from a given global observation in time must be brought to one place to be compared / correlated • => Implies data transfers geographically, globally • Modelling the global VLBI network as a (potentially hierarchically) connected network of “nodules” – Which have capabilities like connectivity (BW, IF types, . . ) storage (size, BW dir limits, . . ), computing, etc. – Which can be remodeled and replaced with new (hierarchical) “nodule” designs without affecting (too much) the “big picture” 7 (17)

Nodules • Pretty much any piece of equipment – (Or a larger collection of Nodules • Pretty much any piece of equipment – (Or a larger collection of such equipment, a “system”) • Which can be described with a small set of capabilities – Connectivity options and capabilities • Interface types, bandwidths, bw / direction limitations – Storage options and capabilities • Device types, r/w bandwidths, bw /direction limitations, sw access methods – Internal CPU, RAM buffering, and data “pumping” power – Packaging options – Price, power consumption, longevity, . . . 8 (17)

Connectivity • All sorts of methods used to transfer data from one place to Connectivity • All sorts of methods used to transfer data from one place to another – – – Physical shipping Networking (both local and global) Device interfaces (e. g. SATA II) Internal buses within equipment VLBI interfaces (e. g. legacy Mark IV formatter if) • Connectivity has a given bandwith and its restrictions – Direction, simultaneous use, less than theoretical performance in a given interconnect, . . . 9 (17)

Existing “Nodules” • Variants of Mark 5 – 5 A, 5 B: 1 Gbps Existing “Nodules” • Variants of Mark 5 – 5 A, 5 B: 1 Gbps in or out /w shipping; 1. 6 Gbps in or out /w sw – 5 B+: 1/2 Gbps in or out /w shipping; 3. 2(? )Gbps in or out /w sw – 5 C: 4 Gbps only in, /w shipping; 3. 2(? )Gbps in or out /w sw • Metsähovi 20 -disk pack /w 10 GE PC – 6 Gbps in or out /w shipping(? ); 6 Gbps in or out /w sw; in&out /w sw not yet tested • Back. Blaze 45 -disk 4 U rackmount /w 1(!)GE PC • Emerging high-end 2 -4 -6 U rackmounts – Claim “up to” 16— 24 Gbps r/w at a premium price 10 (17)

Nodule Jigsaw Puzzle • For instance, try to find a balanced match of storage, Nodule Jigsaw Puzzle • For instance, try to find a balanced match of storage, connectivity, and packaging options to accompany ~CPU • Storage Options • Connectivity Options – 2— 4 SATA II disks – 6 SATA II disks – 2 1 GE ports • 1 Gbps (or a little more) – 3 1 GE ports • 4 Gbps(? ) – 4— 6 SATA II disks + 5 /w PM = ~ 10 SATA II disks – 20 SATA II disks /w PM • 2 Gbps(? ) – 1 10 GE port • 6 Gbps, maybe 8 Gbps – 2 10 GE ports • 6 Gbps – 20— 45 SATA II disks /w many controllers • ? • 8 -10 -? ? Gbps 11 (17)

Packaging Puzzles • Single unit – Tend to become bulky; problems of (semi)custom construction Packaging Puzzles • Single unit – Tend to become bulky; problems of (semi)custom construction • Small-scale rack installation • Full-size rack – Rack connectivity: switches as 24/48 1 GE x 2 10 GE (cheap), 8 10 GE, 24 10 GE (rare, expensive, 10 GE CX->T transition) • Google-style “racks” – Very economical for “ 20 or more small PCs” configuration • But becomes trash in a couple of years and must be thrown away and replaced with a new set. . . • Rack farms 12 (17)

Simultaneous Read and Write • Want to observe (and store a copy of data) Simultaneous Read and Write • Want to observe (and store a copy of data) and at the same time, already start processing • Frequently dictated by the need to use the same (maybe special) connectivity for both directions • Two problems: – HDD seek time, slows down using more than one “spot” of disk – Even without, double data streaming bandwidth required throughout the internal data paths • Seek alleviated by multiplexing HDDs – Means more HDDs needed than the bare minimum – Multiplexing typically in time, in time chunks >>HDD seek time 13 (17)

Imagining the NEXPRe. S WP 8 Nodule. . . • We want more than Imagining the NEXPRe. S WP 8 Nodule. . . • We want more than a trivial single-PC system – But not any large-scale rack systems (no money for that!) • Something that would retain its topology in 2015 – But go from 4— 8 Gbps (NEXPRe. S) to 16— 32 Gbps (2015) • The most obvious Nodule would be a configuration of six 1 GE PCs and one 24 1 GE-to-(1 or 2)10 GE switch – Could do 4 Gbps in or out, 1— 2 Gbps in and out simultaneously – Can exercise multiplexing in time and IP, and multiple nets/PC – The obvious upgrade in 2015 would be to 100% 10 GE • Which means everything---except software! • Might get up to 32 Gbps in or out. . . 14 (17)

Imagining the NEXPRe. S WP 8 Nodule. . . • OTOH, a station Nodule Imagining the NEXPRe. S WP 8 Nodule. . . • OTOH, a station Nodule could be a configuration of two 10 GE PCs and one small 10 GE switch – Could do 8 Gbps in or out, 4 Gbps in and out simultaneously – Can exercise multiplexing in time and IP – The obvious upgrade in 2015 would be to buy more similar PCs • But then: PCs of 2015 will be completely different—a mixed configuration might look weird and make use (=software) more complicated; the 10 GE switch might prove too small and outdated – So might end up buying all new stuff anyway. . . • Will quite likely cost now more than the “six small PCs” scenario • Well, this should be in the Dec-2010 D 8. 1 deliverable. . . 15 (17)

“The Inconvenient Truths” : -) • About e-VLBI: – “A given station cannot really “The Inconvenient Truths” : -) • About e-VLBI: – “A given station cannot really sustain recording bandwidth larger than their e-VLBI connectivity—unless given an unlimited disk buffer. ” – “A single slow (or high-latency like shipping) connection in a given e-VLBI network will force others (or some buffering party) to buffer most of the VLBI data, if not all. ” • About buffers and archives: – “Huge disk buffers with thousands of disks (whether distributed or centralized) will cost a fortune, age rapidly, and be fragile (even with the highest-end equipment) and in constant need of (hw) maintenance. ” 16 (17)

“The Inconvenient Truths” : -) • About Mark 5 s: – “The existing 8 “The Inconvenient Truths” : -) • About Mark 5 s: – “The existing 8 -packs of PATA disks will never be accessed simultaneously read and write—unless Conduant dramatically changes Stream. Stor firmware. ” – “No variant of Mark 5 will ever feed the Mark IV correlator faster than 1 Gbps. While a given Mark 5 unit is feeding the correlator, no new data can be fed into that Mark 5 at the same time. ” – “At 1. 6 Gbps and maybe 3. 2 Gbps in pairs, the existing 8 -PATApacks make little sense in >=4 Gbps buffering. 8 -packs will continue to be useful only for storing data certainly destined to be shipped physically. ” 17 (17)