Extremely slow disk read access software raid 5
 

Hello,

I've just installed a box with Fedora Core 6, using the install program
to setup raid 5 over 3 disks, cele...@1.7ghz.

Now, the read access is descent unbuffered (apx 95mb/s with hdparm). It
feels fairly fast in most operations, but some are dreadfully slow.

For example:
* Copying a directory containig 100 files with cp to the same partition
only takes a whiff.
* Doing the same thing with MC and it only seems to copy one file per
sec.
* FTP Uploading a file to the box - about 10MB/s, Downloading from it
about 3kB/s.

It's the actual disk read that takes forever using some programs. It's
as if some progs use a special way of reading files that doesn't at all
go well with my disk setup.

It only seems to be when reading, but I havn't tested this that much.

Anyone have any ideas?


Running hdparm gives me this:

/dev/sda1:
Timing cached reads: 3032 MB in 2.00 seconds = 1515.26 MB/sec
Timing buffered disk reads: 124 MB in 1.79 seconds = 69.41 MB/sec

It's the same for sdb1 and sdc1 aswell. Looks pretty good, doesn't it?

So I'm confused.

Do your partitions span physical disks? Like are you using local volumes. If so maybe its something with the raid driver instead of something with the disks.

Finally found out what was wrong. It had nothing to do with the disks, what so ever.. It was because of the NIC - Attansic L1.

All I had to do was to disable TSO and it works like a charm. :)