ch5.3 Storage - Troubleshooting Storage, Storage Usage + Quotas Flashcards
ulimit
Bash command that limits the system resources for a user in a Linux-based server
df [options] [object names]
Bash command that displays the device’s storage space
du [options] [object names]
Bash command that displays how a device is used
I/O Scheduling
The process where the OS determines the order of input and output operations as they pertain to block storage devices
CFQ Scheduler
Deadline Scheduler
Noop Scheduler
What file to modify to set the scheduler used by each device?
/sys/block/queue/scheduler
rewatch the scheduler section of the training ->
Section 5: Storage
45. Troubleshooting Storage Issues
starting at 2:13
rewatch the scheduler section of the training ->
Section 5: Storage
45. Troubleshooting Storage Issues
starting at 2:13
iostat
Bash command that generates reports on CPU and device usage (input/output statistics)
IOPS
Acronym that stands for Input/Output Per Second
If there is a low IOPS on a system, you can use the iostat Bash command to identify what kind of input/output is being generated
tps (acronym)
Transfers (I/O requests) per second
kB_read/s (acronym)
Number of blocks read per second
kB_wrtn/s (acronym)
Number of blocks written per second
kB_read (acronym)
Total number of blocks read
kB_wrtn (acronym)
Total number of blocks written
ioping
Generates a report of device I/O latency in real-time
Storage Quota
The storage space allotted to a user for file storage on a computer
Used to prevent users from using up all of the storage space on a system, and either slowing the system down or crashing it.
quotacheck -cug [mount point
Bash command to create quota database files for a file system and check for user and group quotas
edquota -u [username]
Bash command to edit quotas for a specific user
edquota -g [group name]
Bash command to edit quotas for a specific group
setquota -u [username]
Bash command to edit quotas for a specific user
setquota -g [group name]
Bash command to edit quotas for a specific group
How to activate user and group quotas on the file system?
Edit the fstab file to add the options usrquota and grpquota to the relevant file system
(come back here and get the absolute path to the fstab file)
What Bash command can also be used to admin quotas on specifically xfs file systems?
xfs_admin
Quota Reports
Quota Reports are created by the system
Contents of a Report:
Name of the user/group
Number of blocks (in kilobytes) being used
User’s/Group’s storage soft limit
User’s/Group’s storage hard limit
Grace Period
Number of inodes used
Soft limit on inodes
Hard limit on Inodes
repquota -a
Bash command to display the reports for all file systems indicated as read-write with quotas in the mtab file
repquota -u [username]
Bash command to display the report for a particular user
quota -ua [username]
Bash command to display the quota report for a particular user with verbose output
warnquota -u
Bash command to check if users are not exceeding the allotted quota limit
warnquota -g
Bash command to check if groups are not exceeding the allotted quota limit
2nd Stanza
And sweetest - in the Gale - is heard -
And sore must be the storm -
That could abash the little Bird
That kept so many warm -
Go back to the trouble shooter section ->
Section 5: Storage
45. Troubleshooting Storage Issues
starting at 11:59
Go back to the trouble shooter section ->
Section 5: Storage
45. Troubleshooting Storage Issues
starting at 11:59
What tool should be used to create, manage, and monitor a RAID array?
mdadm
What tool allows a system admin to specify how read, write, and status requests are made to a file system?
fuse
