D-Link DSN-6110 User Manual for DSN-6110 & DSN-6110 with DSN-610 - Page 88

DSN-6110 & 6110w/610, What if the snapshot space is over?

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Figure 5.4.4.1 On Linux and UNIX platform, a command named sync can be used to make the operating system flush data from write caching into disk. For Windows platform, Microsoft also provides a tool - sync, which can do exactly the same thing as the sync command in Linux/UNIX. It will tell the OS to flush the data on demand. For more detail about sync tool, please refer to: http://technet.microsoft.com/en-us/sysinternals/bb897438.aspx Besides the sync tool, Microsoft develops VSS (volume shadow copy service) to prevent this issue. VSS is a mechanism for creating consistent point-in-time copies of data known as shadow copies. It is a coordinator between backup software, application (SQL or Exchange...) and storages to make sure the snapshot without the problem of datainconsistent. For more detail about the VSS, please refer to http://technet.microsoft.com/en-us/library/cc785914.aspx. DSN-6110 & 6110w/610 can support Microsoft VSS. • What if the snapshot space is over? Before using snapshot, a snapshot space is needed from RG capacity. After a period of working snapshot, what if the snapshot size over the snapshot space of user defined? There are two different situations: 1. If there are two or more snapshots existed, the system will try to remove the oldest snapshots (to release more space for the latest snapshot) until enough space is released. 2. If there is only one snapshot existed, the snapshot will fail. Because the snapshot space is run out. 88

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88
Figure 5.4.4.1
On Linux and UNIX platform, a command named
sync
can be used to make the operating
system flush data from write caching into disk. For Windows platform, Microsoft also
provides a tool –
sync
, which can do exactly the same thing as the
sync
command in
Linux/UNIX. It will tell the OS to flush the data on demand. For more detail about
sync
tool, please refer to:
Besides the
sync
tool, Microsoft develops
VSS
(volume shadow copy service) to prevent
this issue. VSS is a mechanism for creating consistent point-in-time copies of data known
as shadow copies. It is a coordinator between backup software, application (SQL or
Exchange…) and storages to make sure the snapshot without the problem of data-
inconsistent.
For
more
detail
about
the
VSS,
please
refer
to
.
DSN-6110 & 6110w/610
can support Microsoft VSS.
•
What if the snapshot space is over?
Before using snapshot, a snapshot space is needed from RG capacity. After a period of
working snapshot, what if the snapshot size over the snapshot space of user defined?
There are two different situations:
1.
If there are two or more snapshots existed, the system will try to remove the oldest
snapshots (to release more space for the latest snapshot) until enough space is
released.
2.
If there is only one snapshot existed, the snapshot will fail. Because the snapshot
space is run out.