> Hi!
>
> Have you verified the write performance in Mandrake boxes.. using only
> local
> I/O ?
>
> Something like: "dd if=/dev/zero of=/path/to/file bs=1024k count=1024".
>
> That example will write 1 GB of zero to the file specified.. or to md
> device
> directly. Notice that if you test to md device it will wipe your FS/data
> from the device.
>
> You should get at least 40 MB/sec write performance when using single
> drive,
> and almost certainly more than 100 MB/sec when using 4 drives in raid0.
>
> Verify that, so you can be sure your setup is working properly..
>
> Then check network transfer speed between the initiator and target boxes
> by
> using FTP for example.. in gigabit LAN you should get over 500 Mbit/sec
> easily, also reaching 900 Mbit/sec should not be a problem either.
>
> After that add IETD and see if it's IETD problem.
>
> - Pasi
Thank you very much for the suggestions Pasi! Current transfer rate against
the boot drive on the iSCSI target is ~37MB/s. I haven't tested the raid0 as I
would really like to avoid intentionally wiping out the data I have on there.
The slow performance was noted on both the boot drive and the raid 0, and there
is a big enough difference between the ~3MB/s I'm getting through the MS
Initiator and the ~37MB/s I'm getting on local writes to hopefully rule out
drive write speed on the target boxes as the problem. Transferring 10 1GB
files with FTP from the Initiator machine to one of the target machines (boot
drive) results in a transfer rate of ~30MB/s. Doing a windows copy from the
Initiator local drive to the mounted iSCSI targets results in a transfer rate
around 3MB/s.
Wire speed, using iperf, comes in at about 600Mb/s. I would certainly like
this to increase this to +900Mb/s, but I think I'm currently hitting PCI bus
speed limitations.
With all that said, I'm going to try and switch to the StarPort iSCSI initiator
on the Windows box hopefully before the end of the weekend. Initial testing
I've done with it (iSCSI between my Windows laptop to my Linux laptop) show it
to perform pretty well compared to using the MS Initiator in the same
environment, so it may end up being an issue with the MS Initiator either by
itself, or when used with IETD.
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