On Tue, 5 Jun 2007, Daniel Korstad wrote:
> Sounds like you are well on your way.
> I am not too surprised on the time to completion. I probably
> underestimated/exaggerated a bit when I said after a few hours :)
> It took me over a day to grow one disk as well. But my experience
> was on a system with an older AMD 754 x64 Mother Board with a couple
> SATA on board and the rest on two PCI cards each with 4 SATA ports.
> So I have 8 SATA drives on my PCI (33Mhz x 4 bytes (32bits) = 133MB/s)
> bus of which is saturated basically after three drives.
Related to this question, I have several of my own.
I have an EPoX 570SLI motherboard with 3 SATAII drives, all 320GiB: one
Hitachi, one Samsung, one Seagate. I built a RAID5 out of a partition
carved from each. I can issue a 'check' command and the rebuild speed
hovers around 70MB/s, sometimes up to 73MB/s, and dstat/iostat/whatever
confirms that each drive is sustaining approximately 70MB/s reads.
Therefore, 3x70MB/s = 210MB/s which is a bunch more than 133MB/s. lspci
-v reveals, for one of the interfaces (the others are pretty much the
same):
00:05.0 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a2)
(prog-if 85 [Master SecO PriO])
Subsystem: EPoX Computer Co., Ltd. Unknown device 1026
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 11
I/O ports at 09f0 [size=8]
I/O ports at 0bf0 [size=4]
I/O ports at 0970 [size=8]
I/O ports at 0b70 [size=4]
I/O ports at e000 [size=16]
Memory at fe02d000 (32-bit, non-prefetchable) [size=4K]
Capabilities: [44] Power Management version 2
Capabilities: [b0] Message Signalled Interrupts: Mask- 64bit+
Queue=0/2 Enable-
Capabilities: [cc] HyperTransport: MSI Mapping
which seems to clearly indicate that it is running at 66MHz (meaning
266MB/s maximum). As I say below, the best I seem to be able to get out
of it is 133MB/s, give or take. Can somebody explain what some of those
other items mean, such as 64bit something and different-sized I/O
ports...)
Each drive identifies with different UDMA levels:
The hitachi:
ata1.00: ATA-7, max UDMA/133, 625142448 sectors: LBA48 NCQ (depth 0/32)
The samsung:
ata2.00: ATA-8, max UDMA7, 625142448 sectors: LBA48 NCQ (depth 0/32)
The seagate:
ata3.00: ATA-7, max UDMA/133, 625142448 sectors: LBA48 NCQ (depth 0/32)
I'm trying to determine what the limiting factor of my raid is: Is it
the drives, my CPU (AMD x86_64, dual core, 3600+), my motherboard,
software, or something else. The best I've been able to get in userland
is about 133MB/s (no filesystem, raw device reads using dd with
iflag=direct). What *should* I be able to get?
--
Jon Nelson
<jnelson-linux-raid@xxxxxxxxxxx>
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