I'm ok with the fact that the disks are certainly PATA
with a SATA bridge. Ok also for the PDI bus limitations.
But with one active disk I have 20MB/s, and with two
doing some "complex" operations (file system, not dd) it
drops to 1MB/s. Master and slave on a PATA controller
can even do better! The same setup on the ICH5 SATA
controller works as expected in RAID-0 (with raidframe).

Sebastien

----Original Message Follows----
From: Derek God3 <derek0godfrey@netscape.net>
To: sebastien_erard@hotmail.com
CC: current-users@netbsd.org
Subject: Re: RAID over satalink SATA disks: poor performances
Date: Mon, 29 Dec 2003 12:45:00 -0800

I can not explain the poor perform of simultaneous access but
FYI you can't get 1.5Gb/sec from a sata interface - thats the
bit rate on the serial lines for commands and data not
the overall througput, expect no better than 70MB/sec on a
32/66Mhz PCI bus with todays SATA devices for sustained buffered data. Whats 
more most of the current SATA disks are PATA disks with a front
end chip so you end up with worse than PATA - but there
again nobody is claiming SATA is faster or better :-). I don't
have the 3112 (I have a CN2507) but I bet it isn't allowing overlapped 
access dispite the claim for "two 256 byte, per channel fifo's".
Either that or the PCI bus is bottlenecking

sebastien_erard@hotmail.com wrote:
>Hi,
>
>I have a SATALink 3112 controller with two 120GB SATA hard drives.
>(see below the dmesg output for these devices)
>
>If I access only one of them, I get up to 22MB/s trasfert rate on
>the first GB (ussing dd bs=256k count=4096). Using dd one both
>drives at the same time does not change much.
>
>With a single partition one both of them, using bonnie++ (from
>pkgsrc-current) shows some tranfert rates up to 50MB/s with a 1GB
>file! (I checked this value with 'systat vm', it's impressive!)
>But with bonnie++ on both drives at the same time, I nearly got
>only 1MB/s (still systat vm).
>
>My first idea was to use these two disks in RAID-0 (stripping).
>But I noticed this strange behaviour: poor performance when
>accessing both disks at the same time. Unusable with raidframe.
>
>Is this a known limitation of the SiI3112?
>
>Thanks for any answer,
>Sebastien
>
>PS: It seems that dd is doing some very small transfers, even
>    when specifying bs=256k, something like 11k tps. With
>    bonnie++, I only see 700 to 800 tps. All of this observed
>    witt systat vm.
>
>[dmesg for satalink0, wd0 and wd1]
>satalink0 at pci3 dev 12 function 0
>satalink0: Silicon Image SATALink 3112 (rev. 0x01)
>satalink0: SATALink BA5 register space disabled
>satalink0: bus-master DMA support present
>satalink0: primary channel wired to native-PCI mode
>satalink0: using ioapic0 pin 20 (irq 3) for native-PCI interrupt
>atabus2 at satalink0 channel 0
>satalink0: secondary channel wired to native-PCI mode
>atabus3 at satalink0 channel 1
>...
>satalink0: port 0: device present, speed: 1.5Gb/s
>satalink0: port 1: device present, speed: 1.5Gb/s
>wd0 at atabus2 drive 0: <Maxtor 6Y120M0>
>wd0: drive supports 16-sector PIO transfers, LBA addressing
>wd0: 114 GB, 238216 cyl, 16 head, 63 sec, 512 bytes/sect x 240121728 
>sectors
>wd0: 32-bit data port
>wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
>wd0(satalink0:0:0): using PIO mode 4, Ultra-DMA mode 6 (Ultra/133) (using 
>DMA data transfers)
>wd1 at atabus3 drive 0: <Maxtor 6Y120M0>
>wd1: drive supports 16-sector PIO transfers, LBA addressing
>wd1: 114 GB, 238216 cyl, 16 head, 63 sec, 512 bytes/sect x 240121728 
>sectors
>wd1: 32-bit data port
>wd1: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
>wd1(satalink0:1:0): using PIO mode 4, Ultra-DMA mode 6 (Ultra/133) (using 
>DMA data transfers)
>...
>
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