Shulou(Shulou.com)06/01 Report--

In this issue, the editor will bring you about how to set disk quota in Linux. The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article.

precondition

To make the most effective use of the articles in this series, you should have a basic knowledge of Linux and need to prepare a Linux system to practice the commands introduced in this article. Sometimes different versions of the program have different output formats, so the results you get may not always be the same as the listings and diagrams shown here.

Introduction to quota

Quotas allow you to control the disk usage of a user or organization. It can prevent individual users and organizations from using more than they allow in the file system, or causing complete congestion in the system. The XFS file system also supports project quotas, which limit the amount of space a project can use, regardless of which user creates files in the project's directory tree.

Quotas must be enabled and managed by root users or by users with root privileges. They are often used in multi-user systems and are not often used in single-user workstations.

There are 3 different quota support:

1, vfsold, or version 1 quota

2, vfsv0, or version 2 quota

3. Quotas on the xfs,XFS file system

This article includes version 2 quotas on non-XFS file systems and xfs quotas on XFS file systems. Please note that the LPI 101exams focus on version 2 quotas.

Quotas require kernel support introduced after the 2.4 kernel. The 2.6 kernel also has the support you need.

XFS quotas tend to be journalized. Kernel 2.6.11 and above support journalized version 2 quotas.

Test Settin

First, explain the test partition settings used in this article so that you can better understand some of the examples. If you already understand the file ownership and permissions and have installed the quota package, you can skip directly to the enabling section of the quota. Refer to the learning Linux,101:LPIC-1 roadmap for links to other articles in this series that provide more command details, and only brief instructions are provided here.

Test partitions and users

We use the 110GB ext4 partition (/ dev/sda7) and the 40GB XFS partition (/ dev/sda8) to demonstrate. They are installed in / quotatest/ext4 and / quotatest/xfs, respectively.

Listing 1. Set Partition

[root@echidna] # mkfs-t ext4 / dev/sda7mke2fs 1.41.10 (10-Feb-2009) Filesystem label=OS type: LinuxBlock size=4096 (log=2) Fragment size=4096 (log=2) Stride=0 blocks, Stripe width=0 blocks7159808 inodes, 28637862 blocks1431893 blocks (5.00%) reserved for the super userFirst data block=0Maximum filesystem blocks=4294967296874 block groups32768 blocks per group, 32768 fragments per group8192 inodes per groupSuperblock backups stored on blocks: 32768,98304,163840,229376,294912,819200,884736,1605632,2654208,4096000, 7962624,11239424,20480000 23887872Writing inode tables: doneCreating journal (32768 blocks): doneWriting superblocks and filesystem accounting information: doneThis filesystem will be automatically checked every 28 mounts or180 days, whichever comes first. Use tune2fs-c or-i to override. [root@echidna ~] # mkfs-t xfs / dev/sda8meta-data=/dev/sda8 isize=256 agcount=4, agsize=2622108 blks = sectsz=512 attr=2data = bsize=4096 blocks=10488429, imaxpct=25 = sunit=0 swidth=0 blksnaming = version 2 bsize=4096 ascii-ci=0log = internal log bsize=4096 blocks=5121 Version=2 = sectsz=512 sunit=0 blks, lazy-count=1realtime = none extsz=4096 blocks=0, rtextents=0 [root@echidna ~] # mkdir-p / quotatest/ext4 [root@echidna ~] # mkdir-p / quotatest/xfs [root@echidna ~] # mount / dev/sda7 / quotatest/ext4 [root@echidna ~] # mount / dev/sda8 / quotatest/xfs

In this example, we want the average user to be able to create files in the new file system. Created in this way, the file system is owned by root, and ordinary users cannot create files or directories on the system. We change ownership so that the new file system is owned by the user development who has a dedicated group named development. We change the permissions so that users in the development group can create files and directories. Listing 2 shows how we set ownership and permissions.

Listing 2. Change the ownership and permissions of the test partition

[root@echidna] # # Show default ownership and permissions [root@echidna ~] # ls-l / quotatest/total 4drwxr-xr-x. 3 root root 4096 Nov 18 22:43 ext4drwxr-xr-x. 2 root root 6 Nov 18 22:43 xfs [root@echidna ~] # Change user and group ownership to development [root@echidna ~] # chown development:development / quotatest/* [root@echidna ~] # # Allow group members to create files and directories [root@echidna ~] # chmod Grouw / quotatest/* [root@echidna ~] # ls-l / quotatest/total 4drwxrwxr-x. 3 development development 4096 Nov 18 22:43 ext4drwxrwxr-x. 2 development development 6 Nov 18 22:43 xfs [root@echidna ~] # # Set default group of new files and directories [root@echidna ~] # to development [root@echidna ~] # chmod gears / quotatest/ext4/ [root@echidna ~] # ls-l / quotatest/total 4drwxrwsr-x. 3 development development 4096 Nov 19 11:39 ext4drwxrwxr-x. 2 development development 6 Nov 18 22:43 xfs

We use three users, ian, gretchen and tom, each of whom have the same dedicated group as the user name and are also members of the development group.

Check quota package

If you are using a desktop system, you may not be able to install the quota package because quotas are not installed by a normal default desktop system. Use dpkg or rpm to confirm that you have the package installed, as shown in listing 3.

Listing 3. Check quota package

# On Debian-based systemsian@pinguino:~$ dpkg-l quotaDesired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend | / Err?= (none) / Reinst-required (Status Err: uppercase=bad) | | / Name Version Description+++-====ii quota 4.00~pre1-3 implementation of the disk quota system# On systems that use RPM [ian@echidna ~] $rpm-Q quotaquota-3.17-11.fc13.x86_64 if you do not install the quota package as described in this article Get help on the installation page, "learn Linux,101:Debian package Management" and learn Linux,101:RPM and YUM package Management.

Enabling of quotas

Add quota support to / etc/fstab

The next step in enabling quotas is to add the appropriate option to the file system definition of / etc/fstab, depending on whether you want to implement user quotas, group quotas, or both. The XFS file system also supports project quotas.

At the time of writing, the option to enable quotas is not centrally recorded in an obvious man page. Table 1 shows the available options and the types of quota systems to which they apply.

Table 1. Quota options in / etc/fstab

Options apply to

Use

All types of usrquota

Enable user quotas

Usrjquota=filenamevfsv0

Enable logging of user quotas; requires a quota database file name (usually aquota.user) and specifications for the jqfmt option

Uquotaxfs

Equivalent to usrquota

All types of grpquota

Support for group quotas

Grpjquota=filenamevfsv0

Enable logging group quotas; requires a quota database file name (usually aquota.group) and specifications for the jpfmt option

Gquotaxfs

Equivalent to grpquota

Prjquotaxfs

Enable project quotas

Pquotaxfs

Equivalent to prjquota

Jqfmt=formatvfsv0

Quota format used when usrjquota or grpjquota is specified; currently only vfsv0 is supported

Quotavfsold,vfsv0

Equivalent to usrquota

Noquotavfsold,vfsv0

Do not enable quotas

Uqnoenforcexfs

Enable user quota audit, but cannot enable enforcement measures

Gqnoenforcexfs

Enable group quota auditing, but cannot enable enforcement measures

Pqnoenforcexfs

Enable project quota audit, but cannot enable enforcement measures

We use an ext4 partition and a XFS partition for the demonstration. We will add user and group quotas to these file systems so that you can see how quotas run on two different file systems. Our / etc/fstab input is shown in listing 4.

Listing 4. Enable quota support in / etc/fstab

/ dev/sda7 / quotatest/ext4 ext4 defaults,usrquota,grpquota 1 2/dev/sda8 / quotatest/xfs xfs defaults,usrquota,grpquota 1 2

Reinstall the file system

After editing / etc/fstab and adding quotas, you need to reinstall the file system. For the XFS file system, quota data is part of the file system metadata. For other file systems, user quota information is stored in the aquota.user file of file system root, and group quotas are also stored in aquota.group. Version 1 quotas use quota.user and quota.group. For these file systems, after reinstalling the file system, you must create quota files and enable quota detection. The quotacheck command checks quotas on all file systems, and if the aquota.user and aquota.group files do not exist, the required aquota.user and aquota.group files are created. It can also repair damaged quota files. Check the man page for more information.

The following are some common options that are commonly used with the quotacheck command:

-an or-- all

Check all file systems installed on / etc/mtab (except the NFS file system)

-c or-- create-files

Ignore the current quota file. Run a new scan and write the results to disk

-u or-- user

Check user quotas (default)

-g or-- group

Check group quota

-v or-- verbose

Verbose output

Listing 5 shows the result of running the quotacheck command on our newly installed file system. If you do not use the-an option, you must specify the file system you want to check.

Listing 5. Create quota database files for vfsold and vfsv0

[root@echidna ~] # quotacheck-augvcquotacheck: Skipping / dev/sda8 [/ quotatest/xfs] quotacheck: Your kernel probably supports journaled quota but you are not using it.Consider switching to journaled quota to avoid running quotacheck after an uncleanshutdown.quotacheck: Scanning / dev/sda7 [/ quotatest/ext4] donequotacheck: Cannot stat old user quota file: No such file or directoryquotacheck: Cannot stat old group quota file: No such file or directoryquotacheck: Cannot stat old user quota file: No such file or directoryquotacheck: Cannot stat old group quota file: No such file or directoryquotacheck: Checked 2 directories And 1 filesquotacheck: Old file not found.quotacheck: Old file not found.

Note that the warning from the quotacheck command advises us to use a logged quota instead. Set the options in the ext4 file system / etc/fstab on / dev/sda7 by

Defaults,usrquota,grpquota

Change to

Defaults,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0, you can complete this change.

It is also important to note that the XFS file system can be skipped by the quotacheck command because the XFS quota structure is contained in metadata and logs.

Start or stop quota detection

To enforce vfsold and vfsv0 quota detection, you must enable it using the quotaon command. The commonly used options-a _ moment _ r _ Q _ u and-v have the same meaning as the quotacheck command. Similarly, if you do not specify the-an option, you must specify a file system. If you just want to show quotas on and off, you can use the-p option. Use the quotaoff command to turn off quota detection. Listing 6 shows an example of these commands.

Listing 6. Start quota check for vfsold and vfsv0 quotas

[root@echidna ~] # quotaon-p / quotatest/ext4/group quotaon / quotatest/ext4 (/ dev/sda7) is offuser quotaon / quotatest/ext4 (/ dev/sda7) is off [root@echidna ~] # quotaon-uagv/dev/sda7 [/ quotatest/ext4]: group quotas turned on/dev/sda7 [/ quotatest/ext4]: user quotas turned on [root@echidna ~] # quotaoff-ugv / quotatest/ext4//dev/sda7 [/ quotatest/ext4]: group quotas turned off/dev/sda7 [/ Quotatest/ext4]: user quotas turned off [root@echidna ~] # quotaon-ugv / quotatest/ext4//dev/sda7 [/ quotatest/ext4]: group quotas turned on/dev/sda7 [/ quotatest/ext4]: user quotas turned on

For XFS file systems, quota checking is enabled by default unless the file has uqnoenforce,gqnoenforce or pqnoenforce settings installed. Use the xfs_quota command and the-x (for experts) option to control xfs quotas. Without the-x option, your display of quota information is restricted. The command also has some subcommands, including help, to display a list of available subcommands, state, to show the overall status, enable, to enable quota detection, and disable to stop. The options-u,-g, and-p restrict the behavior of users, groups, or projects, respectively. Use-v to get the verbose output. You can run commands in command line mode, where separate subcommands are indicated by the-c option. You can specify this option for multiple seed commands multiple times. If you will specify options for a subcommand, you may need to reference the command. Some examples are shown in listing 7.

Listing 7. Start quota detection of xfs quota

[root@echidna] # xfs_quota-xxfs_quota > stateUser quota state on / quotatest/xfs (/ dev/sda8) Accounting: ON Enforcement: ON Inode: # 131 (3 blocks, 3 extents) Group quota state on / quotatest/xfs (/ dev/sda8) Accounting: ON Enforcement: ON Inode: # 132 (3 blocks, 3 extents) Project quota state on / quotatest/xfs (/ dev/sda8) Accounting: OFF Enforcement: OFF Inode: 3 extents) Blocks grace time: [7 days 00:00:30] Inodes grace time: [7 days 00:00:30] Realtime Blocks grace time: [7 days 00:00:30] xfs_quota > disablexfs_quota > quit [root@echidna ~] # xfs_quota-x-c "enable-gu-v" / quotatest/xfsUser quota state on / quotatest/xfs (/ dev/sda8) Accounting: ON Enforcement: ON Inode: # 131 (3 blocks 3 extents) Group quota state on / quotatest/xfs (/ dev/sda8) Accounting: ON Enforcement: ON Inode: # 132 (3 blocks, 3 extents) Blocks grace time: [7 days 00:00:30] Inodes grace time: [7 days 00:00:30] Realtime Blocks grace time: [7 days 00:00:30]

Check vfsold and vfsv0 quotas on startup

Although outside the scope of this article, the quotacheck and quotaon commands are usually included in initialization scripts so that quotas can be enabled at the same time whenever you start the system. Quota Mini HOWTO (see Resources for a link) has additional information. If you use log quotas, you do not need to run quotacheck at startup.

Set quota limit

As you can see, quotas are controlled either through binaries in the file system root or through file system metadata. To set a quota for a specific user, use the edquota command. This command extracts quota information for users from various quota-enabled file systems, creates a temporary file, and opens an editor for you to adjust quotas. With the default settings, edquota uses the vi editor. If you want to use a different editor, set the EDITOR or VISUAL variable. Edit the user quota, using the-u option (default) and one or more user names. Edit group quotas, using-g and one or more group names.

You must be a root user to edit quotas. Using vi as the editor, the information displayed is similar to that shown in listing 8.

Listing 8. Run edquota

Disk quotas for user ian (uid 1000): Filesystem blocks soft hard inodes soft hard / dev/sda7 000000 / dev/sda8 000000 ~

As you can see in listing 8, edquota shows my current usage, including 1K modules and inodes on each file system in quota enablement. There are also software and hardware restrictions on the use of modules and index nodes. In this case, they are all 0, meaning there is no quota limit.

The software limit is a value that is the number of times users will receive email warnings when they exceed the quota. The hardware limits the number of times the user cannot exceed. You can think of module limits as appropriate limits on the amount of data that users can store, and index nodes limit the number of files and directories that can be thought of.

Change quota limit

You can change the value in the temporary file, and then save the file to change the quota limit. If you don't want to change, close the file without saving it. We have used very small restrictions in the example so that you can easily see the effect. Suppose you want to set the quota to 10MB data and 50 files on each test file system. Allow an additional 10% hardware limit, which you can set as shown in listing 9.

Listing 9. Set limit

Disk quotas for user ian (uid 1000): Filesystem blocks soft hard inodes soft hard / dev/sda7 0 10240 11264 0 50 55 / dev/sda8 0 10240 11264 0 50 55

Save the file and the new quota will take effect. Note that any changes you make to the module or Inode value you use will be ignored.

Replication of quotas

Now you are going to create an id for additional developers. Suppose you have users gretchen and tom, and you want both of them to have the same quota as ian. You can use the-p option of edquota, which uses ian's quota as a prototype for other user quotas, as shown in listing 10.

Listing 10. Set quotas from the prototype

Root@pinguino:~# edquota-p ian gretchen tom

Group limit

You can also use edquota to limit disk space allocation based on the group ownership of the file. For example, the three developers mentioned above are members of the development group. To set the total amount available to all members of the group to 250MB and 100 files, use the command edquota-g development and set the value, as shown in listing 11.

Listing 11. Set quotas for a group

Disk quotas for group development (gid 505): Filesystem blocks soft hard inodes soft hard / dev/sda7 4 25600 28160 1100110 / dev/sda8 0 25600 28160 0100110

You might wonder why there are already modules and inodes in use on / dev/sda7 's ext4 filesystem. Recall that in listing 2, we used chown and chmod to set the default group for all new files to the development group? This also applies to two quota database files. You can change them back to the values in root, as shown in listing 12. Be sure to make changes after you turn off the quota check, and then turn it on.

Listing 12. Reset the group owner of the quota database file

[root@echidna ~] # quotaoff / quotatest/ext4/ [root@echidna ~] # chown: root / quotatest/ext4/aquota.* [root@echidna ~] # quotaon / quotatest/ext4/

Grace period

Users or groups may exceed the grace period limited by the software, with a default value of 7 days. After the grace period, software restrictions are implemented as hardware restrictions. Once the hardware limit is reached, you must delete some files before creating new files. Use the-t option of edquota to set the grace period. Once again, when you go back to the editor, you will see data similar to that in listing 13. As before, save the changes to update the value. Make sure you have enough time for users to receive warning messages and delete some files accordingly.

Listing 13. Set the grace period

Grace period before enforcing soft limits for users:Time units may be: days, hours, minutes, or seconds Filesystem Block grace period Inode grace period / dev/sda7 7days 7days / dev/sda8 7days 7days

Check quota

The quota command with no option shows the quota for the activated user on any file system, and if the user has files on that system, the quota is set on it. The-v option displays information for all file systems with quotas enabled. Root users can add a user name to the command to view quotas for specific users. In listing 14, we create a 1MB file on the ext4 file system and illustrate the use of the quota command with or without the-v option.

Listing 14. Show quota

[ian@echidna ~] $dd if=/dev/zero of=/quotatest/ext4/ianfile1 bs=1024 count=10241024+0 records in1024+0 records out1048576 bytes (1.0 MB) copied, 0.00793796 s MB/s [ian@echidna ~] $quotaDisk quotas for user ian (uid 1000): Filesystem blocks quota limit grace files quota limit grace / dev/sda7 1024 10240 11264 1 50 55 [ian@echidna ~] $quota-vDisk quotas for user ian (uid 1000): Filesystem blocks quota limit grace files quota limit grace / dev/sda7 1024 10240 11264 1 50 55 / dev/sda8 0 10240 11264 0 50 55

Based on the statistics currently in use, you can see the software and hardware configuration limits that are displayed. If you run the quota command immediately after creating the file, you will see a slightly larger module count display in a short period of time. Listing 15 shows what happens if you exceed the software limit and what happens if you exceed the hardware limit. In this example, we add the 9.5MB file to the created 1MB, which obviously exceeds the software limit. Notice how the software limit gets an asterisk, except that it indicates that the user exceeds the quota. Also note that the grace period column indicates how long it will take the user to solve the problem. When we tried to copy the 1MB file, the operation failed because it exceeded the hardware limit of the user's ian.

Listing 15. Exceed the quota

[ian@echidna ~] $dd if=/dev/zero of=/quotatest/ext4/ianfile2 bs=1024 count=95009500+0 records in9500+0 records out9728000 bytes (9.7MB) copied, 0.0754223 s 129 MB/s [ian@echidna ~] $quotaDisk quotas for user ian (uid 1000): Filesystem blocks quota limit grace files quota limit grace / dev/sda7 10552 * 10240 11264 7days 2 50 55 [ian@echidna ~] $cp / quotatest/ext4/ianfile1 / quotatest/ext4/ianfile3cp: writing `/ quotatest/ext4/ianfile3': Disk quota exceeded

Quota report

Checking quotas for one user at a time is inefficient, so you will want to use the repquota command to generate a quota report. Listing 16 shows how to view quotas for all users and groups on / quotatest/ext4/.

Listing 16. Generate quota report

[root@echidna ~] # repquota-ug / quotatest/ext4/*** Report for user quotas on device / dev/sda7Block grace time: 7days Inode grace time: 7days Block limits File limitsUser used soft hard grace used soft hard grace----root-- 24002 0 0ian +-11260 10240 11264 6days 3 50 55gretchen-2080 10240 11264 44 50 55tom-+ 660 10240 11264 55 50 55 6daysdevelopment-400 100 yuan * Report For group quotas on device / dev/sda7Block grace time: 7days Inode grace time: 7days Block limits File limitsGroup used soft hard grace used soft hard grace----root-- 24 00 20 0development-+ 14004 25600 28160 103 100 110 7days

Notice the plus sign for user ian, tom, and group development in listing 16, which indicates that each now exceeds the quota. User ian has too much data. User tom has too many files. Group development also has too many files.

"as with other quota commands, the-an option generates a report of mounted file systems with quotas enabled." The-v option produces a more detailed output. The-n option generates the number of a numeric user instead of resolving the user number to a name. This will provide a performance boost for large reports, but it is not that useful to readers.

Project quotas on the XFS file system

The XFS quota system also supports project quotas, which are substitutes for group quotas. You cannot use both group and project quotas on the XFS file system. Project quotas are enabled by adding prjquota (or pquota) to / etc/fstab.

Project quotas use the concept of digital id and a more descriptive project name. The file / etc/projects is used to map the digital item identifier to the directory tree, while the file / etc/projid maps the digital item identifier to the project name. You can operate without using these two files in / etc, but this is less convenient. Check the mapping page for more information.

To set project quotas, you must use the xfs_quota command in expert mode (- x option). First you must use the project subcommand and the-s option to set project quotas by marking all affected index nodes as part of the project. Then use the limit subcommand to set hardware or software restrictions. Listing 17 shows how to set a 15MB project hardware limit project tree under / quotatest/xfs/proj-dir1. We will also set up an unlimited parallelism / quotatest/xfs/proj-dir2 to illustrate.

Listing 17. Set xfs project quota

[root@echidna ~] # mkdir-m ag+w / quotatest/xfs/proj-dir {1Yu2} [root@echidna ~] # chown development:development / quotatest/xfs/proj-dir* [root@echidna ~] # echo "50:/quotatest/xfs/proj-dir1" > > / etc/projects [root@echidna ~] # echo "dev-projects:50" > > / etc/projid [root@echidna ~] # xfs_quota-xxfs_quota > path Filesystem Pathname000 / quotatest/xfs/ dev/sda8 (uquota Pquota) [001] / quotatest/xfs/proj-dir1 / dev/sda8 (project 50, dev-projects) xfs_quota > project-s dev-projectsSetting up project dev-projects (path / quotatest/xfs/proj-dir1)... Processed 1 (/ etc/projects and cmdline) paths for project dev-projects with recursiondepth infinite (- 1). Xfs_quota > limit-p bhard=15m dev-projectsxfs_quota > Q

We will explain the project quota by having the user chris create several files. The user chris is not a member of the development group and has not set quotas for himself or the group. Listing 18 shows that chris cannot create data greater than 15MB in / quotatest/xfs/proj-dir1, but there is no limit in / quotatest/xfs/proj-dir2.

Listing 18. Project quota in action

[chris@echidna xfs] $id chrisuid=1010 (chris) gid=1010 (chris) groups=1010 (chris) [chris@echidna xfs] $dd if=/dev/zero of=proj-dir1/chris1 bs=1024 count=1000010000+0 records in10000+0 records out10240000 bytes (10 MB) copied, 0.0379557 s, 270 MB/s [chris@echidna xfs] $cp proj-dir1/chris1 proj-dir1/chris2cp: writing `proj-dir1/chris2': No space left on device [chris@echidna xfs] $ls-l proj-dir1total 15356 RWMut. 1 chris chris 10240000 Nov 23 13:16 chris1-rw-rw-r--. 1 chris chris 5484544 Nov 23 13:16 chris2 [chris@echidna xfs] $# Note: second copy was truncated at hard limit [chris@echidna xfs] $cp proj-dir1/chris1 proj-dir2/chris1 [chris@echidna xfs] $cp proj-dir1/chris1 proj-dir2/chris2 [chris@echidna xfs] $cp proj-dir1/chris1 proj-dir2/chris3 [chris@echidna xfs] $du-sh * 15m proj-dir130M proj-dir2

User warning

The warnquota command is used to issue email warnings to users who exceed quotas. When a group exceeds the quota, an email is sent to the specified user of the group in / etc/quotagrpadmins. The message format is controlled by the file / etc/warnquota.conf. The file / etc/quotatab is used to map the name, for example, / dev/sda7 maps to a description that is easier for the user to understand, such as "Shared EXT3 filesystem". Usually warnquota runs as a cron job on a regular basis. Check out the user's manual page to learn more about cron and warnquota.

This is how to set disk quota in the Linux shared by the editor. If you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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