Re: What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping?
Wojciech Puchar wrote: I am seeing 85MB/s as a speed of a single Hitachi 1TB HD. How high can you go by mirroring or striping 2, 3, 4 harddrives? mirroring - the same, just with 2 processes reading both can get the bandwidth. make sure you use -s high enough (like 1048576) doing gmirror label stripping - the same, or 2,3,4 times, depends how you configure. for highest transfer and lowest concurrency (you mostly read huge files with one process) - use small stripe size. for lowest transfer (=1 disk) and highest concurency - use very huge stripe size like 512MB, so simply different process reading different things can hit different drives, but each I/O isn't spread. So if I will put 6 hard drives with stripping each of them is 85MB/s (in the beginning sectors) I will get 6X85MB/s=4.08Gb/s? Is it reasonable to expect this kind of speed? Something tells me that there will be some other factors like bus speed that would potentially limit the speed in such case. Yuri ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping?
Hi, Yuri On Mon, May 18, 2009 at 4:29 PM, Yuri y...@rawbw.com wrote: So if I will put 6 hard drives with stripping each of them is 85MB/s (in the beginning sectors) I will get 6X85MB/s=4.08Gb/s? Is it reasonable to expect this kind of speed? Something tells me that there will be some other factors like bus speed that would potentially limit the speed in such case. No, that is not reasonable (but in a perfect world, would be correct). You are limited by the bus speed and controller buffer speed (whichever is slower). -- Glen Barber ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping?
Glen Barber wrote: No, that is not reasonable (but in a perfect world, would be correct). You are limited by the bus speed and controller buffer speed (whichever is slower). My motherboard has PCI Express v2.0, that is 500MB/s limitation. Also it has HD/RAID controller Intel ICH10R Southbidge that has peak SATA Data Rate 300MB/s. So this brings me to 300MB/s limit. So 3X harddrives at 85MB/s will still scale. And 4X will already show the limitation. Yuri ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping?
On Mon, May 18, 2009 at 08:07:10PM -0700, Yuri wrote: Glen Barber wrote: No, that is not reasonable (but in a perfect world, would be correct). You are limited by the bus speed and controller buffer speed (whichever is slower). My motherboard has PCI Express v2.0, that is 500MB/s limitation. That's 500MB/s for each PCI-E 2.0 lane. The PCI-E lanes originating at your southbridge (Intel ICH10R) are only PCI-E 1.0 however for a max of 250MB/s per lane (in each direction.) This is irrelevant however since the built-in SATA controller is not attached to any PCI-E lanes. What is relevant is the connection between the northbridge and southbridge. In your case that connection is equivalent to a PCI-E x4 bus, for a max speed of 1GB/s (in each direction.) Also it has HD/RAID controller Intel ICH10R Southbidge that has peak SATA Data Rate 300MB/s. That's 300MB/s for each SATA channel. Unless you use a port-multiplier (which is poorly supported in FreeBSD) you will only have a single disk per SATA channel. So this brings me to 300MB/s limit. So 3X harddrives at 85MB/s will still scale. And 4X will already show the limitation. Actually the buses involved sets the limit at 1GB/s (the Nortbridge-Southbridge connection.) There are likely to be other limits in play however such as the maximum throughput of the SATA controller, or the max load the CPU can sustain, or the transfer speed to RAM. Of these I suspect the controller itself will be the major bottleneck in your case closely followed by the CPU. Exactly how much they can support is not so easily predicted however - it will have to be measured. -- Insert your favourite quote here. Erik Trulsson ertr1...@student.uu.se ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping?
I am seeing 85MB/s as a speed of a single Hitachi 1TB HD. How high can you go by mirroring or striping 2, 3, 4 harddrives? mirroring - the same, just with 2 processes reading both can get the bandwidth. make sure you use -s high enough (like 1048576) doing gmirror label stripping - the same, or 2,3,4 times, depends how you configure. for highest transfer and lowest concurrency (you mostly read huge files with one process) - use small stripe size. for lowest transfer (=1 disk) and highest concurency - use very huge stripe size like 512MB, so simply different process reading different things can hit different drives, but each I/O isn't spread. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping?
I am seeing 85MB/s as a speed of a single Hitachi 1TB HD. How high can you go by mirroring or striping 2, 3, 4 harddrives? Any experiences? Thank you, Yuri ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping?
Yuri wrote: I am seeing 85MB/s as a speed of a single Hitachi 1TB HD. How high can you go by mirroring or striping 2, 3, 4 harddrives? Any experiences? Thank you, Yuri Highly unscientific measurement here, but I seem to be getting a max of ~160 MB/s by striping two Seagate 500Gb drives. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
