Nikolas Britton wrote:
On 7/16/05, Chuck Swiger <[EMAIL PROTECTED]> wrote:
Nikolas Britton wrote:
I was reading on wikipedia about RAIDs trying to pass the time and I
was thinking why not have RAID 5+5 or 5+5+5 levels, sure you waste
2/3th's of your space but wouldn't this be a killer setup for a
directory server where fast reads are of the utmost importance?
Actually, no. RAID-5 prioritizes cost and reliability at the expense of
performance. RAID-5 does adequate for read-mostly volumes with big files, and
does worst with lots of writes to small files.
Ok then, a public FTP server... It doesn't matter, when your have a
405,000 RPM drive (27 drives * 15k rpm) you can do just about
anything, but it would excel for data reads and especially random data
reads.
RAID-5,0 or -1,0 would be a much better choice.
Would you add up the transfer rates for each drive to get the total
transfer rate of the array?, if true you could easily saturate a 10
gigabit ethernet connection with a 555 array of IDE or SATA drives.
Nope. Most machines are limited by their PCI bus and chipset to less than
1Gb/s of backplace bandwidth, although the higher-end boxes with multiple PCI
busses or PCIe will do better.
Yes I realize that the PCI bus is limited to a maximum of 260MB/s
(32-bit @ 66MHz) but PCI-X @ 133MHz is 1060MB/s.... Anyways...
I was just thinking out loud if there would be a useful purpose for
this type of RAID array, I was bored because I had to wait for
ethereal to build and then I had to wait till 3am, to do something,
before I could go to sleep for the night.
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If I am not mistaken the nforce products as well as sis and maybe uli
have direct connect techonlogies for some peripheral to bypass the pci
in there chipsets. All have ide connections (I think) that directly
hook up to the chipset like this to increase performance.
In the nforce products the ata controllers still appear as pci devices,
but only to make it easy on the drivers (I am guessing here). I could
be wrong on some of these products, but I do think most new chipsets
keep hard disks off the pci bus.
A stripped raid array will be faster than raid 5. You only do raid 5 if
you want to have reliability with many disks and waisting have the disks
with mirroring.
Have you seen the IRam from gigabyte? It is not out yet, but you should
google for it. Something like sustained 130-133Mb/s on SATA 150.
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