There is a particular kind of application, single-client and serial process, for which a striped file system using RAM disk would be very useful. Consider reading small blocks at random locations on a hard disk. The latency of the HDD could be a few milliseconds. Adding more HDD's does not solve the problem, unlike an application based on streaming. Adding more disks and parallelizing the program could be a solution but sometimes there is no time to parallelize the program.
A possible solution is RAM disk. But if we put, for example, 64 GB of RAM on a single computer then that computer becomes specialized and expensive, whereas the need for a huge amount of RAM may be only temporary. An alternative is to use a cluster of nodes, a typical Beowulf cluster. For example, using a striped file system over 16 nodes where each node has 4 GB of RAM. Each node would have a normal amount of RAM and yet could provide the aggregate storage of 64 GB when the need arises. While we have not yet created this configuration, I suppose that Gbit Ethernet could provide 100 microsecond latency and Infiniband or Myrinet could provide 10 microsecond latency. Much, much less than the seek time of a HDD. The idea is so simple that I imagine it has already been done. I would be interested in learning from other sites that have used this method with a file system such as Lustre, PVFS2 or another. best regards, Alan Scheinine -- Centro di Ricerca, Sviluppo e Studi Superiori in Sardegna Center for Advanced Studies, Research, and Development in Sardinia Postal Address: | Physical Address for FedEx, UPS, DHL: --------------- | ------------------------------------- Alan Scheinine | Alan Scheinine c/o CRS4 | c/o CRS4 C.P. n. 25 | Loc. Pixina Manna Edificio 1 09010 Pula (Cagliari), Italy | 09010 Pula (Cagliari), Italy Email: [EMAIL PROTECTED] Phone: 070 9250 238 [+39 070 9250 238] Fax: 070 9250 216 or 220 [+39 070 9250 216 or +39 070 9250 220] Operator at reception: 070 9250 1 [+39 070 9250 1] Mobile phone: 347 7990472 [+39 347 7990472] _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
