Guest Peter Posted December 17, 2007 Posted December 17, 2007 Filewrite Performance decreases heavily over time when writing large files (100gb+). we experienced that when dumping large files out from a database. For testing this issue we simply created a small script that generates a file and logs the i/o writing performance. The performance starts at about 125mb/s and then constantly drops over time. after some mins it is down to 20mb/s. The curious thing is if i start a 2nd process while the other is still running the same thing happens again in nearly the same time. my first assumption would have been that the performance should be low allready when starting the 2nd process but the performance over time is nearly the same as with the 1st one. we allready eliminated several things: Volume was on a HP EVA (OS W2k3 SP2 32bit english). But we can also rebuild this on a EMC DMX Volume (OS W2k3 SP1 32bit english). so it shouldnt depend on storage manufacturer. no fragmentation on the volume is given any ideas any1? greetings Peter
Recommended Posts