Date: Wed, 07 Mar 2007 21:36:34 +0100 From: Fluffles <etc@fluffles.net> To: freebsd-geom@freebsd.org Cc: freebsd-stable@freebsd.org, Ivan Voras <ivoras@fer.hr> Subject: Re: Some Unix benchmarks for those who are interesed Message-ID: <45EF2252.1000202@fluffles.net> In-Reply-To: <001601c760ee$f76fa300$0c00a8c0@Artem> References: <20070306020826.GA18228@nowhere> <45ECF00D.3070101@samsco.org><20070306050312.GA2437@nowhere><008101c75fcc$210c74a0$0c00a8c0@Artem> <esk9vq$uhh$1@sea.gmane.org><001a01c7601d$5d635ee0$0c00a8c0@Artem> <eskka8$adn$1@sea.gmane.org><001801c7603a$5339e020$0c00a8c0@Artem> <eskpd1$sm4$1@sea.gmane.org> <20070307105144.1d4a382f@daydream.goid.lan><002801c760e2$5cb5eb50$0c00a8c0@Artem> <esmvnp$khs$1@sea.gmane.org><005b01c760e6$9a798bf0$0c00a8c0@Artem> <esn2s6$1i9$1@sea.gmane.org> <001601c760ee$f76fa300$0c00a8c0@Artem>
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Artem Kuchin wrote: >>> Artem Kuchin wrote: >>> Hmm. what kind of HDD, RAID or whatever are you using? >>> My raid pretty much sucks. It is build it on the intel motherboard >>> LSI Megaraid. But i still get 81Mb/sec when doing >>> dd if=/dev/ar0 of=/dev/null bs=1M >>> >>> How much do you get on this? >> >> geom_mirror on 2 desktop SATA drives, but the results of dd are >> pretty low: >> >> # dd if=/dev/mirror/data of=/dev/null bs=1m count=1000 >> 1000+0 records in >> 1000+0 records out >> 1048576000 bytes transferred in 17.817686 secs (58850290 bytes/sec) >> >> As you can see, results with a single drive are better: >> >> # dd if=/dev/ad4 of=/dev/null bs=1m count=1000 >> 1000+0 records in >> 1000+0 records out >> 1048576000 bytes transferred in 16.219518 secs (64649023 bytes/sec) > > How is it possible that you get 2x file copy perfomance ? What's the > matter?! If you use dd on the raw device (meaning no UFS/VFS) there is no read-ahead. This means that the following DD-command will give lower STR read than the second: no read-ahead: dd if=/dev/mirror/data of=/dev/null bs=1m count=1000 read-ahead and multiple I/O queue depth: dd if=/mounted/mirror/volume of=/dev/null bs=1m count=1000 You can test read STR best with bonnie (see /usr/ports/benchmarks/bonnie); or just with DD on a mounted volume. You should mount with -o noatime to avoid useless writes during reading, or use soft updates to prevent meta data from taking it's toll on I/O performance. - Veronica
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