Adam Goryachev wrote:
>>
>>> The seek time for these may be the real killer since you drag the parity
>>> drive's head along for the ride.
>>>
>> The more drives you have in an array, the closer your seek time will tend to
>> approach worst-case, as the controller waits for the drive with the longest
>> seek time for a given operation. Does anyone know anything about
>> synchronizing drive spindles? I've heard of it, and I know it requires
>> drives that are built for it; but never worked with such hardware.
>>
>>
>
> I was always led to believe that the more drives you had in an array the
> faster it would get. ie, comparing the same HDD and controller, if you
> have 3 HDD in a RAiD5 it would be slower than 6 HDD in a RAID5.
If you are writing big files, the transfer throughput will go up because
you effectively stripe the data and can write more concurrently and
without additional head motion.
> Is that an invalid assumption?
If you are writing small files and doing directory operations you are
back to waiting for the heads to seek.
> How does RAID6 compare in all this? Would
> it be faster than RAID5 for the same number of HDD's ? (Exclude CPU
> overheads in all this)
I think raid 6 just adds an extra parity write so you can lose 2 disks
out of the array without failing.
--
Les Mikesell
[EMAIL PROTECTED]
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