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Storage Procurements

Storage Procurements

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Storage Procurements

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  1. Storage Procurements Some random thoughts on getting the storage you need Martin Bly Tier1 Fabric Manager

  2. You want How Much? • Know your units • TB (10^12) is not the same as TiB (2^40) • Storage vendors talk in terms of TB and raw capacity • Define what you mean by 1TB and what you mean by your capacity requirements • For the Tier1 procurements: • Capacity in units of 1TB=10^12 bytes • Usable capacity described in terms of RAID5 or RAID6 redundancy (or even RAID 1+0) • Thus N data drives will give (N-2)*Size_of_drives usable storage (R5,6) Stoarge Procurements - HEPSysMan @ RAL

  3. Storage type • Lots of sorts • SAN, NAS, DAS, iSCSI… • Different technologies • FC, SCSI, SAS, SATA • Arrangement • RAID levels, array/server arrangements • Each appropriate for different use cases • Speed, cache/buffer sizes (disk, controller), battery backup units Stoarge Procurements - HEPSysMan @ RAL

  4. Technical specs • Specify what *you* want • In as much detail as is necessary to get it • Be as unambiguous as possible • Three types of specification: • Mandatory – non-compliant if not provided • Desirable – you’d like it but omission is not a non-compliance • Optional – gives the vendor some scope for added value • Specify *everything* • Including CPU performance, RAM, NICs, which OS, acceptance tests, documentation requirements, maintenance and warranty etc • Provide required (achievable!) performance metrics • And a recipe to do the tests… • Define bid evaluation criteria before issuing the spec or call for tender Stoarge Procurements - HEPSysMan @ RAL

  5. Technology issues • Motherboard SATA controllers, NICs • Issues with concurrent i/o performance of 3ware cards • Are the drivers required for the components you need available in the version of the OS you intend to run • If not – are you prepared to build extra modules for them, and do it every time a new kernel comes along until it *is* available in the stock builds: c.f. areca driver in SL 4.6, kernel >= 2.6.9-67.0.15 • And you may have to add them to the installation kernel… Stoarge Procurements - HEPSysMan @ RAL

  6. Technology Issues II • In RAID systems, number of drives per controller: • Fewer drives, fewer concurrent drives used for read or write, lower performance • More drives, better performance, but performance drops off across the Span • Large RAID sets on single controllers are not recommended, though more than one RAID per controller seems OK Stoarge Procurements - HEPSysMan @ RAL

  7. Technology Issues III • Capacity per box • I/O bandwidth to disks • I/O bandwidth to network • Memory – is more better • CPU architecture • OS issues • Resilience • Reliability Stoarge Procurements - HEPSysMan @ RAL

  8. Large Procurements • Where value large => EU tender rules • Avoid specifications that mention Tradenames, OEM names, non-benchmarked performance indicators, proprietary technologies… • Unless referring to a common name for a part to a recognised industry standard • ‘commando’ plugs are IEC.309 / BS EN.60309-2 • But quote the standard first • Use ISO, EN or BS standards • ISO and EN take precedence over BS where there is an equivalent EN. Some EN standards adopted as the BS. • Be prepared for a long process • Restricted: longer, two stages, get to restrict the final bidders • Open: shorted, many more bidders to evaluate • Can use Catalyst (GCAT) or other schemes • For small volumes, exercise your supplier contacts Stoarge Procurements - HEPSysMan @ RAL

  9. Random thoughts • Weight, cooling, power consumption, power feeds, power redundancy, NIC redundancy, switch uplink capacity, warranty, availability of spares after maintenance period, Castor/dCache/DPM/xrootd, disks/controller, controllers/chassis, RAM per chip/core, chips/cores per chassis, redundant system drives, lights-out operation, component quality, interoperability with existing systems, chunk size Stoarge Procurements - HEPSysMan @ RAL