On 3/5/06, Beastie <[EMAIL PROTECTED]> wrote:
Nikolas Britton wrote:
On 3/3/06, Alex Zbyslaw <[EMAIL PROTECTED]> wrote:
Nikolas Britton wrote:
Please can you be careful when you attribute your comments. You've sent
this
email "to" me, and left only my name in the attributions as if I
were
someone suggesting either dd or diskinfo as accurate benchmarks,
when in
fact my contribution was to suggest unixbench and sandra-lite.
Maybe you
hate those too, in which case you can quote what I said
in-context and
rubbish that at your pleasure.
Yes I see your point, it does look like I'm replying to something you
wrote.
This was a oversight and I am sorry.
OK.
Remember that 105MB/s number I quoted above?, that's just the
sustained read
transfer rate for a big ass file, I don't need to work
with big ass files. I
need to work with 15MB files (+/- 5MB). After
buying the right disks,
controller, mainboard etc. and lots of tuning
with the help of iozone I get:
200 - 350MB/s overall (read, write,
etc.) for files less then or equal to
64MB*.
So anyways, that's what iozone can do for you. google it and
you'll
find out more stuff about it.
Thanks for the info. I think I can only dream about numbers like like
yours.
Iozone looks to be in the ports so I see some of my weekend
disappearing
looking at it :-)
It runs on over two dozen operating systems, including windows. Their are
two primary reasons I can get such high transfer rates from simple SATA
drives. The first one was the selection of the mainboard that had a PCI-X
slots, I built this system before PCI-Express mainboards and controllers hit
the market. The PCI bus is severely restricted and obsolete, I'm simply
going to post the theoretical maximum throughput in MB/s for the various bus
standards: f(x,y) = x-bits * y-MHz / 8 = maximum theoretical throughput in
MB/s PCI: 32 bits * 33 Mhz / 8 = 132 MB/s (standard PCI bus found on every
pc) PCI: (32bits, 66MHz) = 264MB/s (Cards are commonplace, mainboards
aren't) PCI-X: (64, 33) = 264MB/s (obsolete, won't find it on new boards.)
PCI-X: (64, 66) = 528MB/s (Commonplace.) PCI-X: (64, 100) = 800 PCI-X: (64,
133) = 1064 (Commonplace.) PCI-X: (64, 266) = 2128 PCI-X: (64, 533) = 4264
(very hard to find, even on high-end equipment.) PCI-X version 1 (66MHz -
133MHz) and PCI-X version 2 (266MHz - 533MHz). PCI-X is backwards compatible
with PCI and slower versions of PCI-X, for example you can put a standard
PCI card in a PCI-X 533MHz slot and it will simply run at (32, 33) similarly
a 66 MHz PCI card will run at (32, 66) and so on and so forth. PCI-X is also
forwards compatible in the fact that you can run a 133MHz PCI-X card in a
standard (32, 33) PCI slot. Because of the backwards and an forwards
compatibly I feel that PCI-X is superior to PCI-Express, *BUT* PCI-Express
moving forwards is far far superior to PCI & PCI-X because it does not have
13 years of legacy to remain compatible with, it's cheaper to produce, and
it's already in lower-end desktop systems as a replacement for AGP thanks to
all the gamers. A few years from now PCI will end up where ISA / EISA are.
I'm veering way off topic so I will not go into anymore details about PCI,
PCI-X, and PCI-Express. Google around for the shortcomings of PCI / PCI-X
and why PCI-Express is the future. PCI-Express: PCIe is not compatible with
PCI or PCI-X (except for PCIe to PCI bridging) and it's just, well, totally
different from the PCI spec and I'm already way off topic so again just
google the details. It's theoretical maximums are expressed in Gigabits per
second but I will convert them to MB/s for comparison with PCI and PCI-X.
x1: 2.5Gbps = 312.5MB/s x2: 625MB/s x4: 1250MB/s x8: 2500MB/s x12: 3750MB/s
x16: 5000MB/s x32: 10000MB/s Anyways back on topic, what was the topic? Oh
yes, why you won't see 200MB/s - 350MB/s if your using a standard PCI slot.
If you look back up all the way at the top you will see that the standard
PCI bus is a crap shoot and that it's limited to a theoretical maximum of
132 MB/s. What this means is that your RAID controller and the disks
attached to it and the cache buffers attached to the disks are all capped at
that theoretical maximum of 132MB/s. Then you have to take into account that
the PCI bus is shared with other devices such as the network card, video
card, USB, etc. Your RAID controller has to fight will all these devices and
a 1Gbit NIC card can eat up 125MB/s (12.5MB/s for a 100Mbit NIC). The next
reason for those high gains is because I picked drives with 16MB cache
buffers and that I'm insane enough to run a production server with the
write-back cache policy enabled on the array controller and enabling the
write cache on the disks. This is stupidly insane unless you've planned for
the worsts. The worst case scenario would be that you corrupt the array into
an unrepairable state and loose everything if you had a power failure. --
BSD Podcasts @ http://bsdtalk.blogspot.com/
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attach iozone result of amrd0 with 4 spindle Seagate Baracuda 300 Gb SATA II
(1 hotspare)
w/ Intel SRCS16 PCI-X
Is that fast or what ? :)
I'll have to take a closer look, but the first thing I noticed in your
test report is that you are only using a 1MB test file. You should run
a test that will also max out the on disk / controller buffers. I
think the Baracuda's have a 16MB buffers (16MBx4=64MB) so try a 128MB
test file. Also be nice to see more detailed hardware specs about the
system and what version of FreeBSD are you running.
Thanks.
--
BSD Podcasts @ http://bsdtalk.blogspot.com/
