Copyright@1994~2015
Advanced
Computer
&
Network
Corp.
All
Rights
Reserved.
66
JetStor
NAS
724UX
/
724UX
10G
–
User
Manual
TIP:
“Compression”
options:
Disabled:
No
compression
at
all.
Default
value.
Zero
Reclaim:
When
the
data
block
contains
all
zeros,
no
physical
space
will
be
consumed.
The
block
will
be
marked
specifically.
Generic
Zero
Reclaim:
This
is
JetStor
patent
filing
technology
that
will
reclaim
data
blocks
with
special
patterns
such
as
all
0’s,
all
1’s.
Theoretically,
it
will
have
better
storage
efficiency.
Enabled:
This
will
always
enable
lossless
data
compression
function
using
LZJB
algorithm.
TIP:
“Sync”
means
synchronous
I/O,
which
is
similar
to
the
definition
of
write
‐
through.
Synchronous
I/O
is
that
every
file
system
transaction
is
written
and
flushed
to
stable
storage
devices
by
a
system
call
return.
The
application
needs
to
wait
for
the
physical
data
update
completion
before
it
could
issue
another
command.
Latency
will
be
longer
and
performance
will
suffer.
If
you
don’t
know
how
to
use
this
setting,
please
leave
it
as
default.
Disabled:
All
write
commands
become
asynchronous.
It
will
ignore
the
synchronous
transaction
demands
of
applications
such
as
database
or
NFS.
Standard:
The
default
value.
It
depends
on
the
applications.
Always:
All
write
commands
become
synchronous
even
if
the
application
issues
asynchronous
transactions.
The
“Sync”
option
will
be
grey
out
if
“volume”
is
selected
instead
of
file
system.
This
is
because
synchronous
write
function
is
not
supported
in
iSCSI
block
access
for
the
time
being.
TIP:
“Number
of
data
copies”
in
Create
File
System
or
Volume
UI
is
used
to
create
mirroring
of
data
to
avoid
data
corruption.
When
the
original
file
corrupts,
the
system
will
use
the
extra
“copy”
to
recover
the
corrupt
file.
The
value
of
two
means
that
when
you
copy
a
10MB
file,
it
will
take
up
20MB
space.
The
value
of
three
means
that
it
will
take
up
extra
double
space
to
store
the
same
data
in
the
same
storage
pool.
Users
will
not
be
able
to
see
the
actual
extra
copies.
They
are
controlled
by
the
file
system.
Thin
provisioning
The
following
are
the
thin
provision
features:
Dynamic
allocating
space
to
store
user
data.
Applied
to
both
file
system
and
volume.
Remove
stranded
or
reserved
‐
but
‐
unused
capacity.
Improve
storage
efficiency.
