Re: Huge Data sets, simple queries

Jim,

On 1/31/06 3:12 PM, "Jim C. Nasby" <jnasby(at)pervasive(dot)com> wrote:

>> The alternating technique in mirroring might improve rotational latency for
>> random seeking - a trick that Tandem exploited, but it won't improve
>> bandwidth.
>
> Or just work in multiples of tracks, which would greatly reduce the
> impact of delays from seeking.

So, having rediscovered the facts underlying the age-old RAID10 versus RAID5
debate we're back to the earlier points.

RAID10 is/was the best option when latency / random seek was the predominant
problem to be solved, RAID5/50 is best where read bandwidth is needed.
Modern developments in fast CPUs for write checksumming have made RAID5/50 a
viable alternative to RAID10 even when there is moderate write / random seek
workloads and fast read is needed.

>>
>> Works great with standard OS write caching.
>
> Well, the only problem with that is if the machine crashes for any
> reason you risk having the database corrupted (or at best losing some
> committed transactions).

So, do you routinely turn off Linux write caching? If not, then there's no
difference.

- Luke