Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 30 Sep 2003 13:39:23 +0200 | From | Christoph Klocker <> | Subject | datatransfer slow down with 1TB files |
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Hi I am developing a system to stream large uncompressed videofiles which are about 1,5TB. I need a bandwith of 195MB/s (HD-SDI) my system is now: RH8 - kernel: 2.4.18 xeon 2,4GHz 1GB RAM 3ware escalade controller 12 s-ata harddisks (seagate barracuda 7200.7 - 120GB - SCSI)
when I do different tests with bonnie++ I get very good results for a 2GB file, sequential input 236mb/s, but when the files get larger the speed is going down significantly. at 10GB - 216MB/s at 100GB - 187MB/s at 1TB - 161MB/s the sequential output stays at 183MB/s any time, up to 1TB. As my harddisks have a sustained rate of 32-50 MB/s each it should not be the case that they influence the results. I also tested the raid full up to 1,2TB and there was no difference in the results. Best filesystem performance I tested was on XFS or EXT2 I applied min-readahead to 128 and max-readahead to 256
I tested also with lmdd with the O_DIRECT option, and get lower results. lmdd if=internal of=fred bs=2m count=1000 fsync=1 direct=1 2097.1520 MB in 12.5588 secs, 166.9860 MB/sec
the driver for the videocard I use don't support 2.6 please reply personally thanks christoph
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