Messages in this thread | | | Date | Wed, 9 Dec 1998 10:20:58 -0500 (EST) | From | Gregory Maxwell <> | Subject | Re: Dumb question: Which is "better" SCSI or IDE disks? |
| |
On Tue, 8 Dec 1998, Christopher Smith wrote:
> On Tue, 8 Dec 1998, Leonard Zhang System Administrator ISD RVIB wrote: > > RAID-1 is disk mirror. DPT is cache with RAID. RAID will increase the > > disk performance. > Ugh.. FYI, RAID does not always increase disk performance, and in > particular RAID-1 is guarunteed not to increase disk performance by it's
What? Join the real world but. Raid-1 doubles read throughput and the slowdown of writes is negligable.
> very nature (ok, it's conceivable that read performance could be > increased somewhat, but write performance would, if anything, be decreased > somewhat). Again, if the cache is actually playing a role in this > benchmark, then what you are really saying is that IDE is so fast that > it's 4x faster than DPT's cache memory. Think about that for a minute.
Come off it, when you do disk benchmarks you use a dataset sufficently large so that the cache doesn't matter. Linux does caching just fine, DPT's cache is somewhat redundant.
Almost all other raid levels perform worse (like raid 5 where the fastest write takes 2 reads 1 block XOR and 1 write).
The fastest raid array is a combo of raid-0(striping) and raid-1.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |