I am currently having a problem with a small Linux server that is providing file-sharing services to four Windows 7 32-bit clients. The server is an AMD PhenomX3 with two Western Digital 10EADS (1TB) drives, attached to a Gigabyte GA-MA770T-UD3 mainboard and running Ubuntu Server 10.04.1 LTS.
The client machines are taking an extremely long time to access/transfer data on the file server. Applications often become non-responsive while trying to open files located remotely, or one program attempting to open a file but having to wait will prevent other software from accessing network resources at all. Other examples include one image taking 20 seconds or more to open, and in one instance a user waited 110 seconds for Microsoft Word 2007 to save a document.
I had initially thought the problem was network-related, but this appears not to be the case. All cables and switches have been tested (one cable was replaced) for verification. This was additionally confirmed when closing down all client machines and rebooting the server resulted in the hard-drive light staying on solid during the startup process. For the first 15 minutes during boot, logon and after logging on (with no client machines attached), the system displayed a load average of 4 or higher. Symptoms included waiting several minutes for the logon prompt to appear, and then several minutes for the password prompt to appear after typing in a user name. After logon, it also took upwards of 45 seconds for the 'smartctl' man page to appear after the command 'man smartctl' was issued. After 15 minutes of this behaviour, the load average dropped to around 0.02 and the machine behaved normally.
I have also considered that the problem is hard-drive-related, however diagnostic programs reveal no drive problems. Western Digital DLG, Spinrite and SMARTUDM show no abnormal characteristics - the drives are in perfect health as far as the hardware is concerned.
I have thus far been completely unable to track down the cause of this problem, so any help is greatly appreciated.
Output of 'free'
hxxp://pastebin.com/mfsJS8HS (stupid spam filter)
The command 'hdparm -d /dev/sda1' reports: HDIO_GET_DMA failed: Inappropriate ioctl for device (the BIOS is set to AHCI - I probably should have mentioned that).