[Samba] Miserable read performance (factor ~60 too slow)

Andrew Morgan morgan at orst.edu
Thu Jul 5 17:47:09 GMT 2007

On Thu, 5 Jul 2007, Arno Schäfer wrote:

> Hi,
> I am trying to migrate my files from a Windows XP Pro box to a new server 
> running OpenSuSE 10.2/Linux 2.6.18 (x86_64) and Samba 3.0.25b.
> The Server is a new Athlon 64 X2 4000+/1GB with two 400GB SATA disks in a 
> software RAID1 configuration. The share file system is reiserfs on a 350GB 
> RAID1 partition.
> I have a small LAN with three PCs on 100MBit Ethernet and a Laptop on WLAN on 
> a 4 Port Switch/WLAN/DSL router.
> I am experiencing extremely (an I really mean EXTREMELY) bad performance. It 
> is so bad that it can not have anything to do with performance "tuning", it 
> must be a configuration error somewhere.
> Doing some comparisons, I find that
> - copying a 700MB file from the CIFS share of the Windows XP box to a 
> different Windows PC starts immediately and takes about two minutes.
> - copying the same file via HTTP from the new Samba server takes a little 
> more than one minute (10.5 MB/sec).
> - copying the file from the Samba share varies hugely. It can take between 90 
> seconds and literally hours (!).
> - sometimes it goes faster, but almost always the startup time is between 20 
> and 90 seconds, that is the time before the copying even begins.
> - I have found repeatedly that when I am copying a file from the Samba share, 
> and it goes extremely slow (estimated time 90 minutes), and I start copying a 
> second file (from the same or a different PC), suddenly the copying speeds up 
> to "normal" speed.
> ifconfig does not show any collisions or errors, and as I said, copying via 
> HTTP is extremely fast.
> The Linux installation is as barebones as I could make it, no X11, no 
> firewall (for now), no ZENWorks or AppArmor or anything. I already once 
> reinstalled everything from scratch, to no avail.
> Any ideas would be immensely appreciated, as I am seriously considering going 
> back to Windows XP ;-)

You have an Ethernet duplex mismatch between your server and the switch 
port.  Based on the symptoms you describe, your server is probably at full 
duplex and the switch port is at half duplex.


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