Hard Drives going bad, how to get SATA/ATA device information.
# hdparm -tT /dev/sda
/dev/sda:
Timing cached reads: 582 MB in 2.00 seconds = 290.60 MB/sec
Timing buffered disk reads: 96 MB in 3.05 seconds = 31.49 MB/sec
Harddrives come in three kinds: Sata, Ide, and Scsi. Many type of hardware error will how up under linux if you use the command “dmesg”. In fact, almost any type of hardware error or information will show up there.
If you think your drive may be sub par, or you want to test it, then hdparm is a good command.
[~]# hdparm -tT /dev/sda
/dev/sda:
Timing cached reads: 270 MB in 2.01 seconds = 134.60 MB/sec
Timing buffered disk reads: 80 MB in 3.07 seconds = 26.10 MB/sec
If the second measurement is under 40MB/sec then you shoud change the drive for your server.
Below is the measurement for a new server.
[~]# hdparm -tT /dev/sda
/dev/sda:
Timing cached reads: 12252 MB in 2.00 seconds = 6135.69 MB/sec
Timing buffered disk reads: 212 MB in 3.01 seconds = 70.51 MB/sec
Note: SMART allows you to have a good degree of prediction on when the drive will reach its end of life.
What is the difference between Domain disk space and Hard disk quota?
Domain disk space - a calculation of everything the domain uses disk space for i.e. web, mail, databases, etc.
Hard disk quota - a calculation of disk space used by a domains ftp user account i.e. web files.
Domain disk space
This is how much disk space is used by the entire domain. It is made up of Plesk statistics and includes the amount of disk space taken by web pages, mail accounts, databases and other domain data including options specified in the statistic settings on Server -> Server preferences page in the Plesk CP.
Hard disk quota
Is a file system feature that limits how much disk space can be taken by the files which are owned by a specific system account (either domain FTP user or webuser or subdomain FTP user).
This file system quota cannot be exceeded. If the limit is reached, the system user will not be able to create new files and will receive the error “no more space left on device”.
Reference : http://parallels.com
Users are not allowed to create hard links for directories. This might transform the directory tree into a graph with cycles, thus making it impossible to locate a file according to its name.
Links can be created only among files included in the same file system. This is a serious limitation since modern Unix systems may include several file systems located on different disks and/or partitions, and users may be unaware of the physical divisions between them.
In order to overcome these limitations, soft links (also called symbolic links) have been introduced. Symbolic links are short files that contain an arbitrary path name of another file. The path name may refer to any file located in any file system; it may even refer to a nonexistent file.
The Unix command:
Creates a new soft link with path name f2 that refers to path name f1.
