On Fri, Jan 27, 2006 at 12:55:18PM -0800, Scott Harrington wrote:
> Hello everyone. I am new to this list, so please accept my apology if
> this has been covered at some point in the past (I did check archives
> though). Also, I hope this is the correct place for this.
>
> I don't even know if my problem is IETD specific, but I'm fresh out of
> ideas. I will try to include as much information as possible, while
> attempting to keep it relevant. I've been trying to solve this problem
> for going on two months now with no luck.
>
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
> I currently have 4 boxes running Mandrake 10.2 and IETD 0.4.13. Kernel
> version is 2.6.15. All the boxes are identical with a Celeron 2.8 and
> 512MB of RAM. Each box has an 80GB IDE boot drive and 4x300GB SATA
> drives configured as a raid 0 under /dev/md0. IETD is configured with
> Lun 0 Path=/dev/md0,Type=fileio. These boxes are all connected together
> with DLink DGE-530T gigabit NICs to an EG008W gigabit switch (dedicated
> to the iSCSI targets and initiator) with no jumbo frame support.
> Incidentally, the motherboards are Intel D915GAGLK boards and the
> onboard gigabit NICs don't work reliably with any kernel I have tried.
>
> At the initiator end I have a Windows 2000 box running MS's 2.0 iSCSI
> Initiator software. It attaches to each target, and then I have it set
> up to software raid 0 the 4 mounted iSCSI targets to make one ~4.3TB
> drive. I am aware that there is no redundancy anywhere, but that's ok
> for my purpose - I'm using it as a Disk-to-Disk-to-Tape solution. If a
> drive fails I know I will have to rebuild the whole thing, but that's
> fine with me. The Windows box runs Veritas Backup Exec 9 and backs up to
> the "local" D: drive (the mounted ~4.3TB volume). The Windows box is a
> P4 3.0 with 2GB of RAM and an Intel dual port gigabit network card.
>
> Now the problem; writes are slow. Very, very slow. This can be simply
> copying a file to the drive, or using Backup Exec to backup to the
> drive. To give an example, a 407GB backup I just finished running
> completed with an average speed of 204MB per minute. The verify
> (reading) finished with an average speed of 2,571MB per minute.
> Duplicating the data to tape now is streaming through at ~350MB per
> minute which is pretty much the maximum write speed to each tape drive.
> The 407GB of data came from a 2Gb/s fiber channel array connected to the
> Initiator box via gigabit, but the same problem is observed when trying
> to copy data from the local C: drive on the Initiator box to the mounted
> iSCSI volume.
>
> To try and exclude the Linux raid as being the source of the problem, I
> created a 20GB file on the IDE boot drive of one of the iSCSI target
> machines. I then set it up as a target and mounted it on the Windows
> box. Unfortunately I noticed the same write performance problems. I
> have tried a variety of configuration changes, none of which have made
> any difference at all. If there is more info you want, I'd be happy to
> provide it. If anyone could possibly provide any help I would be very
> grateful. I think it is maybe cache related as copies / backups usually
> start to go very quickly, but then taper off to very slow after about 10
> seconds or so.
>
>
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