Slow file copy

[russofris]

Good evening,

I am having trouble with HDD to HDD file moves/copies. Moving data from disk to disk seems to transfer at a rate of approx 6MB/sec on hardware capable of much more than that. The problem seems to be limited to the PATA disks in my system. SCSI is unaffected. Here's the setup.

1:WD120BB as /dev/hda. Master (single) on Via KT333 onboard controller.
2:Maxtor 160GB D540X as /dev/hde. Master (single) on PDC20276 onboard controller.
3:Maxtor 160GB D540X as /dev/hdg. Master (single) on PDC20276 onboard controller.

hdparm info. DMA is enabled, all drives are running at ata100. multi is 16, 32 bit transfers enabled on all drives. Uncached reads are as follows.

1:WD120BB at 39MB/sec
2:D540X at 27MB/sec
3: Same as 2 (it's the same model)

Symptoms:
When I copy/move a file from drive to drive in konqueror or from the CLI, the transfer rate is approximately 6MB/sec. Under dos and win32 I get about 25MB/sec. CPU utilization goes to 100% during the transfer.

The only thing that I can think of is that DMA is not 'actually' enabled for the drives on the PDC20276. Has anyone else experienced similar results? Is there some "write-verify" flag that exists in the newer kernels that could be causing this? Seems to happen with all of the 2.6 kernels I have tried.

Thank you for your time,
Frank Russo


Info is as follows:

[yaneurabeya]

Just as a side question, have you tried timing file copies and moves with mv and cp? I know it might be trivial, but just wondering if the issue is with konqueror or the drives.

[xbmodder]

[joeswift]

check out the performance options in this url attached:

http://www.laukas.com/knbase/linux_special/

You may find some hardware optimizatio setting that you can perform to improve loads. I have found in the past that piping output from one location to another is faster than running cp. For instance using tar and then piping to another location copies across by blocks (so you block size could be adjusted to increase performance for larger files). Using cp copies by characters, which could slower

[russofris]

I took a look at the performance tips, and aside from the filesystem block size, I do not believe that any of the others would make a huge difference (having already set up the hdparm tweaks). The problem is that the current FS is EXT2 on my drives. I intentionally chose this for it's low CPU overhead (and it appears that I am CPU limited on the file transfers). While increasing the block size will reduce the symptoms, I do not believe it will solve the actual problem; which is that file transfers across ATA disks peg the CPU regardless of the DMA setting.

Strange. I will keep looking.

Frank

[joeswift]

what does lspci tell you about the drives? emerge pciutils if you havent yet to get lspci

[russofris]