36.4GB drive formats out to 32.8GB? what am I missing please
grep sectors /var/run/dmesg.boot
lists at dylangoss.com
Tue Jun 14 17:51:06 GMT 2005
On Jun 14, 2005, at 8:48 AM, Wojciech Puchar wrote:
> think twice before making RAID-5 array. are you sure small writes
> will not be too common?
No, you are on to something - I will be making small writes / parity
calculations. This is going to be a web server but it is for clients
and they do have sites running with SQL backends and not just static
> i think buying 4 80GB FAST IDE/SATA drives and arranging it as
> RAID-10 will give you 160GB of FAST and protected storage.
> performance gain using mirror+strip will likely offset this of
> using faster 15k rpm drives.
> and it will be for sure cheaper. you may put 6 drives (RAID-10) and
> even larger drives and still have cheaper alternative and even
> faster. and MUCH more space.
Sure, it will be cheaper. For me it's too late, I've purchased the 4
x SCSI 15k drives I need for this project. I have bought mostly
unopened, in-box but secondhand IBM drives/sleds. They are still
expensive but certainly not the (what I consider) insane prices for
the same drives IBM direct. I'm paying around 1/3 of "list".
I'm curious as to if you're right, I'll certainly have something to
run some benchmarks on soon. Keep in mind this is all running though
hardware raid (IBM ServeRAID 6i). Somehow I feel that 15k SCSI on
U320 being processed as RAID-5 with this card will be better than you
state. You're right, it will have cost more than IDE but I wanted to
give this approach a try.
Worst thing is that I can fall back to SCSI 1+0 as you suggest at the
cost of one drive's space. My guess is that while the drives are
clean I will play with both structures for the RAID and compare some
benchmarks to give me an idea of what kind of hit the parity is
Thanks for you comments.
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