On Aug 27, 2012, at 1:31 PM, Vincent Diepeveen wrote: > Yeah it will be a great machines. You get what you pay for of course. > Confirming that is not even interesting. If you pay big bucks > obviously it'll be fast. > > For such machines, just break the raid card during operation, then > replace it with another > card and see whether your data still is there and whether it can > work without too much problems > within the crucial 2 minutes that you've got normally at exchanges > to get new equipment in > (not counting rebuild time), or you're fired. > > So for rich financials i bet such machines are attractive. > > As for HPC, scaling is important. > > As for cheap scaling.... > > If i search for benchmarks of raid controllers, you can find > everything as well. > > What really misses is benchmarks of built in raid controllers. > > If you want to scale cheap it's interesting to know how to do the i/ > o obviously. > > The motherboards i've got have the ESB2 from intel built in as RAID > controller. > > If i google i see nothing on expected read/write speeds. > > Nearly all raid controllers you always see have a limit of 1 GB/s, > that really sucks > compared to even the bandwidth one can generate to the RAM. > > Basically 1 GB/s with 8 cores Xeon 2.5Ghz means you've got 8 * > 2.5Ghz = 20k cycles a byte, or 32k instructions you can > execute for reading or writing just 1 byte.
Oh dear calculations on monday... ...make that 20Ghz * 4 instructions per cycle / 1 GB = 80 cycles a byte... Or for each 'bitboard' which is 64 bits, so similar to a double, if you read and write it. You read 2 and write 1. That's 24 bytes of i/o. So that's 80 cycles * 24 = 1920 instructions. I didn't factor in SSE4.2 yet... For i/o intensive applications bandwidth is interesting to have to the i/o. I don't see how file servers deliver that for clusters. > > Most raid controllers that are cheap, say a 100-300 euro (130 - 400 > dollar), they're not managing more than a > write speed of a 600MB/s , that's in fact in raid-0, not really > realistic, and 700-900MB/s read speed. > > That's with around a drive or 8. > > We know however that when the raid array is empty, those drives > will handsdown get a write speed at outside of drives of > a 130MB/s, so the limitation is the raid cards CPU itself. Usually > around a 800Mhz at the better cards. > > Many benchmark with SAS drives. I see some fujitsu drives that are > rated 188MB/s at outer side of drives, which benchmark to > 900MB/s readspeed. > > The limitation seems to be the raidcards in most cases. > > So my simple question would be: is this better with the built in > raid controllers that most motherboards have as they can use > the fast 2.5Ghz Xeon cpu's? > > On Aug 26, 2012, at 12:22 AM, hol...@th.physik.uni-frankfurt.de wrote: > >> Hello Beowulf 2.0 >> >> I've just started playing with NFSoIB to provide super fast backend >> storage for a bunch of databases that we look after here. Oracle and >> Nexenta are both sending me ZFS based boxes to test and I hope to >> compare >> the performance and stability of these with the Netapp (formally lsi >> engenio) E5400. >> >> This will be the first time I will be getting into serious storage >> benchmarking. Does anyone have any interesting tests they would >> like to >> run or and experience performing these kinds of tests? >> >> I have 4 HP G8 boxes with 96GB ram each QDR IB and 10G ethernet as >> consumers. >> >> I will also be testing the performance of KVM and Virtuozzo >> (commercial >> version of OpenVZ) which is a kernel sharing virtualization >> similar to BSD >> Jails. >> >> Thanks, >> >> Andrew >> >> _______________________________________________ >> Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin >> Computing >> To change your subscription (digest mode or unsubscribe) visit >> http://www.beowulf.org/mailman/listinfo/beowulf > _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
