Raid 5 performance

[Todd Lewis]

I am using FreeBSD 4.9, with a 3ware RAID 5
1 gig memory 2.8g p4

Three questions.

1. FreeBSD has a 16k block size. The RAID card is set at 64k
    Block size(its sweet spot). My logic tells me that
    increasing the block size to 64k would increase disk
    read and write access. But, everything I read suggest
    going above 64k is dangerous. Are their any recomendations
    on performance a stability concerns when increasnig the
    block size to 64k when using a RAID controler.

2. The vfs.hirunningspace variable defualts to 1meg. From what I've
    read this looks like a buffer. I'm guessing that its set to
    1meg becuase most drives have 1~2 megs of memory. So following
    that logic and with safety in mind. For drives with 4 megs
    cache, I would set vfs.hirunningspace to 2 megs. 8megs of cache
    4 megs to vfs.hirunningspace. So, my 64 megs raid control would
    have a vfs.hirunningspace 32.
3. Any other stellar performance info would be appriciated.


netstat -m

mbuf usage:
        GEN list:       4/480 (in use/in pool)
        CPU #0 list:    443/656 (in use/in pool)
        Total:          447/1136 (in use/in pool)
        Maximum number allowed on each CPU list: 512
        Maximum possible: 51200
        Allocated mbuf types:
          358 mbufs allocated to data
          89 mbufs allocated to packet headers
        2% of mbuf map consumed
mbuf cluster usage:
        GEN list:       12/564 (in use/in pool)
        CPU #0 list:    263/304 (in use/in pool)
        Total:          275/868 (in use/in pool)
        Maximum number allowed on each CPU list: 128
        Maximum possible: 25600
        3% of cluster map consumed
2020 KBytes of wired memory reserved (32% in use)
0 requests for memory denied
0 requests for memory delayed
0 calls to protocol drain routines

dd if=/dev/da0s1f of=/dev/null bs=1m count=100

code:
100+0 records in
100+0 records out
104857600 bytes transferred in 6.331798 secs (16560478 bytes/sec)