On Sat, 7 Nov 1998, Stephen Costaras wrote:
> Seeing as we're all using RAID here, someone might know how to eek
> better performance out of a I/O subsystem.
>
> I'm using a Dual PPro system (Tyan S1668) with 3 Mylex KT-958
> controllers. Each controller has 3 Seagate Barracuda ST15150W
> drives (fast/wide, approx. 5MB/sec internal transfer bandwidth).
> I have all nine disks in a RAID 5 array, so I figure 15*3=45MB/sec
> usable bandwidth. Raidtab has everything configured for 64k chunks.
--snip--
> (system has 256MB memory, CPU utilization is around 50-60% of one CPU,
> kernel=
> 2.0.35)
> -------Sequential Output-------- ---Sequential Input-- --Random--
> -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
> news:md0 1000 6213 89.0 11416 50.6 4412 34.4 6813 73.3 8395 23.8 149.7 10.0
Here's are some more (RAID0 _not_ 5) numbers for comparison. Mine is
a dual 233MHz ppro (Intel Providence PR440FX), 128MB RAM, with a single
Mylex 958 on which are RAIDed 6 Seagate Hawk ST32155W (2GB) disks. Note
that these disks belong to a previous generation -- Seagate no longer
sells them.
Kernel is 2.1.125 with 19981106-C-2.1.125 patches. Slowest and fastest
configurations are given below.
***************** RAID0: 4KB chunk, 1KB block, stride=4
[root@iam /zu]# bonnie -s 512 -m "raid0,4k" -d /zh
File '/zh/Bonnie.3754', size: 536870912
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
raid0,4k 512 3917 94.9 17706 77.2 6511 50.6 3773 80.7 19187 64.8 138.7 4.9
***************** RAID0: 32KB chunk, 4KB ext2 block, stride=8
[root@iam /zu]# bonnie -s 512 -m "raid0,32k,4k,8" -d /zg
File '/zg/Bonnie.3780', size: 536870912
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
raid0,32 512 3684 99.3 24511 65.4 9543 58.0 4569 94.2 22334 51.1 214.1 5.9
