<s>
A	O
disk	B-Application
quota	I-Application
is	O
a	O
limit	O
set	O
by	O
a	O
system	B-Application
administrator	I-Application
that	O
restricts	O
certain	O
aspects	O
of	O
file	B-Application
system	I-Application
usage	O
on	O
modern	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
The	O
function	O
of	O
using	O
disk	B-Application
quotas	I-Application
is	O
to	O
allocate	O
limited	O
disk	O
space	O
in	O
a	O
reasonable	O
way	O
.	O
</s>
<s>
There	O
are	O
two	O
basic	O
types	O
of	O
disk	B-Application
quotas	I-Application
.	O
</s>
<s>
The	O
first	O
,	O
known	O
as	O
a	O
usage	O
quota	B-Application
or	O
block	O
quota	B-Application
,	O
limits	O
the	O
amount	O
of	O
disk	O
space	O
that	O
can	O
be	O
used	O
.	O
</s>
<s>
The	O
second	O
,	O
known	O
as	O
a	O
file	O
quota	B-Application
or	O
inode	O
quota	B-Application
,	O
limits	O
the	O
number	O
of	O
files	O
and	O
directories	O
that	O
can	O
be	O
created	O
.	O
</s>
<s>
In	O
addition	O
,	O
administrators	O
usually	O
define	O
a	O
warning	O
level	O
,	O
or	O
soft	O
quota	B-Application
,	O
at	O
which	O
users	O
are	O
informed	O
they	O
are	O
nearing	O
their	O
limit	O
,	O
that	O
is	O
less	O
than	O
the	O
effective	O
limit	O
,	O
or	O
hard	O
quota	B-Application
.	O
</s>
<s>
There	O
may	O
also	O
be	O
a	O
small	O
grace	O
interval	O
,	O
which	O
allows	O
users	O
to	O
temporarily	O
violate	O
their	O
quotas	B-Application
by	O
certain	O
amounts	O
if	O
necessary	O
.	O
</s>
<s>
Disk	B-Application
quotas	I-Application
are	O
typically	O
implemented	O
on	O
a	O
per-user	O
or	O
per-group	O
basis	O
.	O
</s>
<s>
That	O
is	O
,	O
a	O
system	B-Application
administrator	I-Application
defines	O
a	O
usage	O
or	O
file	O
quota	B-Application
specific	O
to	O
a	O
certain	O
user	O
or	O
group	O
.	O
</s>
<s>
In	O
some	O
filesystems	B-Application
(	O
e.g.	O
</s>
<s>
ext4	B-Application
,	O
XFS	B-Application
,	O
f2fs	B-Application
,	O
ZFS	B-Application
,	O
Lustre	O
)	O
it	O
is	O
also	O
possible	O
to	O
also	O
define	O
block	O
and	O
inode	O
quota	B-Application
limits	O
for	O
a	O
particular	O
project	O
or	O
directory	O
,	O
by	O
adding	O
a	O
project	O
ID	O
to	O
files	O
that	O
directory	O
tree	O
and	O
defining	O
quota	B-Application
limits	O
for	O
the	O
project	O
ID	O
.	O
</s>
<s>
In	O
doing	O
so	O
,	O
an	O
administrator	O
can	O
prevent	O
one	O
user	O
from	O
consuming	O
an	O
entire	O
file	B-Application
system	I-Application
's	O
resources	O
,	O
or	O
create	O
a	O
system	O
of	O
tiered	O
access	O
,	O
whereby	O
users	O
can	O
have	O
different	O
levels	O
of	O
restriction	O
.	O
</s>
<s>
In	O
most	O
cases	O
,	O
quotas	B-Application
are	O
also	O
specific	O
to	O
individual	O
file	B-Application
systems	I-Application
.	O
</s>
<s>
Should	O
an	O
administrator	O
want	O
to	O
limit	O
the	O
usage	O
of	O
a	O
specific	O
user	O
on	O
all	O
file	B-Application
systems	I-Application
,	O
a	O
separate	O
quota	B-Application
would	O
have	O
to	O
be	O
specified	O
on	O
each	O
.	O
</s>
<s>
When	O
a	O
soft	O
quota	B-Application
is	O
violated	O
,	O
the	O
system	O
normally	O
sends	O
the	O
user	O
(	O
and	O
sometimes	O
the	O
administrator	O
as	O
well	O
)	O
some	O
sort	O
of	O
message	O
.	O
</s>
<s>
Some	O
systems	O
prevent	O
disk	O
write	O
operations	O
that	O
would	O
result	O
in	O
hard	O
quota	B-Application
violations	O
from	O
completing	O
successfully	O
,	O
while	O
others	O
wait	O
until	O
the	O
quota	B-Application
has	O
been	O
physically	O
violated	O
before	O
denying	O
write	O
requests	O
.	O
</s>
<s>
Disk	B-Application
quotas	I-Application
are	O
supported	O
by	O
most	O
modern	O
operating	B-General_Concept
systems	I-General_Concept
,	O
including	O
Unix-like	B-Operating_System
systems	I-Operating_System
,	O
such	O
as	O
AIX	B-Application
(	O
using	O
JFS	B-Application
or	O
JFS2	B-Application
filesystem	B-Application
)	O
,	O
Linux	B-Application
(	O
using	O
ext3	B-Application
,	O
ext4	B-Application
,	O
ext2	O
,	O
XFS	B-Application
(	O
integrated	O
support	O
)	O
among	O
other	O
filesystems	B-Application
)	O
,	O
Solaris	B-Application
(	O
using	O
UFS	B-Operating_System
or	O
ZFS	B-Application
)	O
,	O
Microsoft	B-Application
Windows	I-Application
starting	O
with	O
Windows	B-Application
2000	I-Application
,	O
Novell	B-Operating_System
NetWare	I-Operating_System
,	O
VMS	B-Operating_System
,	O
and	O
others	O
.	O
</s>
<s>
The	O
method	O
of	O
administration	O
for	O
disk	B-Application
quotas	I-Application
varies	O
between	O
each	O
of	O
these	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Unix-like	B-Operating_System
systems	I-Operating_System
typically	O
provide	O
a	O
quota	B-Application
command	O
for	O
both	O
administration	O
and	O
monitoring	O
;	O
graphical	O
front-ends	O
to	O
the	O
command	O
may	O
also	O
be	O
used	O
.	O
</s>
<s>
Unix	O
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
frequently	O
feature	O
a	O
grace	O
period	O
where	O
users	O
may	O
exceed	O
their	O
quota	B-Application
limits	O
for	O
a	O
brief	O
period	O
of	O
time	O
.	O
</s>
<s>
Windows	B-Application
2000	I-Application
and	O
newer	O
versions	O
use	O
the	O
"	O
Quota	B-Application
"	O
tab	O
of	O
the	O
disk	O
properties	O
dialog	O
.	O
</s>
<s>
Other	O
systems	O
provide	O
their	O
own	O
quota	B-Application
management	O
utilities	O
.	O
</s>
<s>
quota	B-Application
-	O
display	O
a	O
user	O
's	O
file	B-Application
system	I-Application
disk	B-Application
quota	I-Application
and	O
usage	O
;	O
</s>
<s>
edquota	O
-	O
Edit	O
user	O
quotas	B-Application
for	O
file	B-Application
system	I-Application
;	O
</s>
<s>
setquota	O
-	O
Set	O
disk	B-Application
quotas	I-Application
for	O
file	B-Application
system	I-Application
;	O
</s>
<s>
repquota	O
-	O
Summarize	O
quotas	B-Application
for	O
a	O
file	B-Application
system	I-Application
;	O
</s>
<s>
quotacheck	O
-	O
File	B-Application
system	I-Application
quota	B-Application
consistency	O
checker	O
;	O
</s>
<s>
quotaon	O
-	O
Turn	O
file	B-Application
system	I-Application
quotas	B-Application
on	O
and	O
off	O
;	O
</s>
<s>
/etc/fstab	B-Protocol
(	O
Linux	B-Application
)	O
or	O
/etc/vfstab	B-Protocol
(	O
Solaris	B-Application
)	O
-	O
list	O
of	O
default	O
parameters	O
for	O
each	O
file	B-Application
system	I-Application
including	O
quota	B-Application
status	O
.	O
</s>
