Yeah, there's no value in using the /dev/random devices for testing disk i/o. Use /dev/zero instead. I've known of hardware RAID engines in the past that can recognize certain repeating i/o benchmark patterns and optimize for them, but I have no idea if LSI controllers do this, tho based on your results it's probably safe to say that they don't. Scott On Jun 20, 2010, at 1:09 PM, Artem Belevich wrote: > /dev/random and /dev/urandom are relatively slow and are not suitable > as the source of data for testing modern hard drives' sequential > throughput. > > On my 3GHz dual-core amd63 box both /dev/random and /dev/urandom max > out at ~80MB/s while consuming 100% CPU time on one of the processor > cores. > That would not be enough to saturate single disk with sequential writes. > > --Artem > > > > On Sun, Jun 20, 2010 at 9:51 AM, oizs <oizs_at_freemail.hu> wrote: >> I've tried almost everything now. >> The battery is probably fine: >> mfiutil show battery >> mfi0: Battery State: >> Manufacture Date: 7/25/2009 >> Serial Number: 3716 >> Manufacturer: SMP-PA1.9 >> Model: DLFR463 >> Chemistry: LION >> Design Capacity: 1800 mAh >> Design Voltage: 3700 mV >> Current Charge: 99% >> >> My results: >> Settings: >> Raid5: >> Stripe: 64k >> mfiutil cache 0 >> mfi0 volume mfid0 cache settings: >> I/O caching: writes >> write caching: write-back >> read ahead: none >> drive write cache: default >> Raid0: >> Stripe: 64k >> mfiutil cache 0 >> mfi0 volume mfid0 cache settings: >> I/O caching: writes >> write caching: write-back >> read ahead: none >> drive write cache: default >> >> Tried to play around with this as well, with almost no difference. >> >> Raid5 >> read: >> dd if=/dev/mfid0 of=/dev/null bs=10M >> 1143+0 records in >> 1143+0 records out >> 11985223680 bytes transferred in 139.104134 secs (86160083 bytes/sec) >> write: >> dd if=/dev/random of=/dev/mfid0 bs=64K >> 22747+0 records in >> 22747+0 records out >> 1490747392 bytes transferred in 23.921103 secs (62319342 bytes/sec) >> >> Raid0 >> read: >> dd if=/dev/mfid0 of=/dev/null bs=64K >> 92470+0 records in >> 92470+0 records out >> 6060113920 bytes transferred in 47.926007 secs (126447294 bytes/sec) >> write: >> dd if=/dev/random of=/dev/mfid0 bs=64K >> 16441+0 records in >> 16441+0 records out >> 1077477376 bytes transferred in 17.232486 secs (62525939 bytes/sec) >> >> I'm writing directly to the device so im not sure any slice issues could >> cause the problems. >> >> -zsozso >> On 2010.06.20. 4:53, Scott Long wrote: >>> >>> Two big things can affect RAID-5 performance: >>> >>> 1. Battery backup. If you don't have a working battery attached to the >>> card, it will turn off the write-back cache, no matter what you do. Check >>> this. If you're unsure, use the mfiutil tool that I added to FreeBSD a few >>> months ago and send me the output. >>> >>> 2. Partition alignment. If you're using classic MBR slices, everything >>> gets misaligned by 63 sectors, making it impossible for the controller to >>> optimize both reads and writes. If the array is used for secondary storage, >>> simply don't use an MBR scheme. If it's used for primary storage, try using >>> GPT instead and setting up your partitions so that they are aligned to large >>> power-of-2 boundaries. >>> >>> Scott >>> >>> On Jun 18, 2010, at 6:27 PM, oizs wrote >>> >> >> _______________________________________________ >> freebsd-current_at_freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-current >> To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org" >> > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org"Received on Sun Jun 20 2010 - 17:27:48 UTC
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