Robin H. Johnson wrote:
The single PMP numbers they have (under "Addonics ADSA3GPX8-4EM Striped RAID Set
Performance Comparison") has Write=211MB/sec Read=231MB/sec.
True. I wonder if the bus spec of 3Gb/s is somewhat optimistic in the
real world - a bit like saying one can get 132MB/s from a 32bit 33MHz
PCI bus.
The absolute ideal throughput for 1.5 Gb/s would be 187MB/s, so the
throughput figures above mean the link must be at 3Gb/s, it's just not
inpressive, given that the 5 drives can do at least 300MB/s and the
theoretical maximum for 3Gb/s is 375MB/s.
In another test at the same site, a Marvell 88SX7042 based card gets
slightly better throughput - 196.8 write 251 read:
http://www.amug.org/amug-web/html/amug/reviews/articles/sonnet/e4p/
Looking at the graphs towards the end of the article "Seagate 160GB
7200.9 Port Multiplier Write/Read Performance", it looks as though
better performance may be had by distributing disks across multipole PM
ports, rather than all on one - see 5 drives on one PM v 4 drives, each
on it's own PM.
There are quite a number of tests of many PM cards and enclosures here:
http://www.amug.org/amug-web/html/amug/reviews/reviews.html
Regards,
Richard
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