--- John MacLerran <[log in to unmask]> wrote:

> actually, i thought raid5 had a problem with writes always being
> slower than other topologies, due to the number of discs in a raid
> group.
>
> i seem to remember reading somewhere that the write performance of
> raid5 is exacerbated if the application does lots of non-sequential
> writes of small chunks of data. since that's basically what our
> systems do, it seems intuitive that we'd want to maximize our write
> performance, and, since we can afford to 'waste' half the disc space,

> then raid 1/0 is the way to go. the 165gb will give us about 65gb
> more space than we have on our nikes, and about 100gb more than we're

> currently using.

i'm way out on a limb...but i can report what i'm seeing with my
a-/n-class boxes and va7100.

the read/writes to the va just fly.  it's truely rare to see the system
paused for disc.  i very much think it's because of the pci
architecture in combination with the fibre channel interface.  life in
'pci' land is radically different from life in 'nio' land.

i should add that i also put extra cache on my va.  did i need?  i
don't know...no one from hp could advise me one way or another.  is it
hurting...probably not.  fair chance that it is helping....

look at it this way....running raid 5 is going to give you plenty of
disc.  may give you the opportunity to look like a hero down the road
:-)           - d

=====
Donna Garverick     Sr. System Programmer
dgarverick -at- longs -dot- com
925-210-6631        Longs Drug Stores

Come, my friends, 'Tis not too late to seek a newer world.
Tho' much is taken, much abides; and tho'
We are not now that strength which in old days
Moved earth and heaven, that which we are, we are.
"Ulysses", A. Tennyson

>>>MY opinions, not Longs Drug Stores'<<<




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