Read throughput between RAID 10 and RAID 5

I know writes to RAID 5 are slower than RAID 10( I think). What about when
it comes to reading data ? Is it the same between reading from RAID 5 and
RAID 10 or is one faster than the other ? If so, let me know which one.
ThanksThey're fundamentally similar because they both use striping to improve read
performance.
Here's how I look at the read characteristic trade off when comparing RAID10
vs RAID5
For a given number of disks, RAID10 has the disadvantage that it throws half
the space away with mirroring. This means that you have fewer disks to
spread your stripes accross & therefore less read capacity. This is a real
limitation on many systems because most people have limited budgets & can
only squeeze a fixed number of maximum drives into whatever hardware they
have.
On the other hand RAID10 doesn't have the parity calculation overhead
associated with RAID5. This does have an effect on read operations because
the disks spend more time on write operations with RAID5 which has an
indirect impact on reads - the disks have less time to read because they're
spending more time writing on RAID5.
So, it's a scenario specific trade off that you need to evaluate for your
own system. The more read-oriented the workload, the better off you are with
RAID5. The more write intensive, the better off you are with RAID10.
It's also important to take RAM into consideration as well because most read
activity can be off-loaded to the buffer cache, never hitting the disks.
This generally makes the argument for RAID10 stronger..
HTH
Regards,
Greg Linwood
SQL Server MVP
http://blogs.sqlserver.org.au/blogs/greg_linwood
"Hassan" <hassan@.hotmail.com> wrote in message
news:O5Ei0jkfHHA.284@.TK2MSFTNGP05.phx.gbl...
>I know writes to RAID 5 are slower than RAID 10( I think). What about when
>it comes to reading data ? Is it the same between reading from RAID 5 and
>RAID 10 or is one faster than the other ? If so, let me know which one.
> Thanks
>|||Just to add to what Greg Linwood said.
It often helps to look at a storage subsystem not only in terms of its RAID
configuration, but all the components on the I/O path including the RAID
config. For instance, with enough disks, you may find the type of RAID confi
g
is less a factor than your controller in your read throughput because the
latter may have now become the bottleneck limiting your read throughput.
Linchi
"Hassan" wrote:

> I know writes to RAID 5 are slower than RAID 10( I think). What about when
> it comes to reading data ? Is it the same between reading from RAID 5 and
> RAID 10 or is one faster than the other ? If so, let me know which one.
> Thanks
>
>