Getting Error Disk quota exceeded

Hi i have a domain roboshop.in
I am getting the following error in my front end and backend
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Warning: session_start() [function.session-start]: open(/tmp/sess_557f9ef253bffb4a5c39554948520561, O_RDWR) failed: Disk quota exceeded (122) in /home/robos7mj/public_html/system/library/session.php on line 11Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/robos7mj/public_html/index.php:104) in /home/robos7mj/public_html/system/library/session.php on line 11Warning: fopen(/home/robos7mj/public_html/system/cache/cache.language.1443503950) [function.fopen]: failed to open stream: Disk quota exceeded in /home/robos7mj/public_html/system/library/cache.php on line 32Warning: fwrite() expects parameter 1 to be resource, boolean given in /home/robos7mj/public_html/system/library/cache.php on line 34Warning: fclose() expects parameter 1 to be resource, boolean given in /home/robos7mj/public_html/system/library/cache.php on line 36Warning: fopen(/home/robos7mj/public_html/system/cache/cache.currency.1443503950) [function.fopen]: failed to open stream: Disk quota exceeded in /home/robos7mj/public_html/system/library/cache.php on line 32Warning: fwrite() expects parameter 1 to be resource, boolean given in /home/robos7mj/public_html/system/library/cache.php on line 34Warning: fclose() expects parameter 1 to be resource, boolean given in /home/robos7mj/public_html/system/library/cache.php on line 36
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I didn't get what is exactly the problem is this .
Can anyone help me to resolve this problem.
Please reply as soon as possible.

It's liierally what the error says - you've run out of disk space.

If on shared hosting, it is also possible the area where the /tmp/ folder is has run out of space rather than it being your website space, in which case you'll have to request help from your host to ideally get the /tmp/ folder moved into your own hosting space.