●
SDPE Capacity
Snap Data Pool Element (SDPE) is a unit of pool area to be allocated from an SDPV to an SDV (copy
destination area). When data is written to the copy destination, the SDP is divided into small units called
SDPE, so that only as much as is required is used.
1GB, 2GB, or 4GB can be specified for an SDPE unit. Specify as small a value as possible, because the usage
efficiency of area allocation improves as the SDPE unit becomes smaller.
The maximum SDP capacity differs depending on the specified SDPE unit. When a small value is specified for
the SDPE, the maximum SDP capacity will be smaller. Because a storage area exceeding the copy source
capacity (logical SDV capacity) that was specified during the SDV creation cannot be supplied, set a large
value to the SDPE capacity only when the total data capacity that is to be saved to the SDV exceeds the total
SDP capacity that is to be created.
●
Number of SDPVs
Multiple SDPVs with a maximum of 2TB capacity can be created. When SDPVs are created, the total capacity
of the SDPVs is pooled as an SDP.
Distribute SDPVs to multiple RAID groups so that the load is not concentrated on a specific drive. In addition,
distribute controlling CMs of the RAID groups where the SDPVs are created so that load is balanced.
When SDPVs are concentrated on one RAID group, the time required for restoration increases as the number
of snapshot generations to acquire increases.
■
How to Check Snapshot Data
Acquired snapshot data can be verified from the client with the following methods.
●
CIFS Client
Identical to Windows shadow copy, snapshot data can be verified from the client using Explorer. Open the
directory or file properties and when the [Previous Versions] tab screen is selected, a list of collected data is
displayed.
●
NFS Client
After a shared folder is mounted, snapshot data can be referred to from the ".snap" directory under that
shared folder.
Snapshots are saved to directories that are created using the acquisition time stamp as the name under the
".snap" directory in the shared folder.
A directory is created according to the following naming rule.
@GMT—yyyy.mm.dd—hh.mm.ss
"yyyy.mm.dd" indicates year/month/day, "hh.mm.ss" indicates the Greenwich Mean Time (GMT) and the
seconds (ss) are rounded off.
For example, when "/mnt/share_dir/" is mounted as the shared folder, the snapshot of file (A) in the shared
folder is acquired to the following destination (B).
A. Copy source file
/mnt/share_dir/aaa.txt
(*1)
B. Snapshot destination
/mnt/share_dir/.snap/@GMT—2019.06.10—09.13.00/aaa.txt
(*2)
*1:
"/mnt/share_dir/" is the mount point of the shared folder.
*2:
"@GMT—2019.06.10—09.13.00" is the directory where the snapshots acquired at 9:13 AM on June 10, 2019 are saved.
4. NAS Functions
Snapshot
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Design Guide
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