User`s manual

RNAS-1200 Series Managing Drives and Storage
7-5
JBOD
JBOD stands for "Just a Bunch Of Drives". In this configuration, each memory drive is treated as an
independent volume, with no collective properties of any kind. JBOD configurations offer standard performance
with a standard failure rate and normal data security.
Big
The BIG configuration is also called SPANNING. Both disks are concatenated together as if they were one single
drive, or one very large logical volume. BIG is different from RAID 0 because there is no striping of data
involved: each drive handles data at the file level, without any write or read sharing between devices. BIG
configurations have no data redundancy, offer no increase in performance, and have a failure rate double that
of JBOD. Alongside RAID 0, BIG/SPANNING configurations are significantly less reliable and secure than other
configurations.
RAID 0
This configuration stripes data across two physical disks as if they were a single, larger disk. Because both disks
operate as one, the read-write heads are doubled, providing much faster read-write times. However, there is
no data redundancy, so if one drive fails all data across both disks will be lost, simultaneously. This effectively
doubles the configuration's failure rate. RAID 0 provides a moderately increased read-write performance at a
significant cost to reliability and security.
RAID 1
For the RAID 1 configuration, all data is fully duplicated, with one drive mirroring and journaling all data
recorded to the other drive. This provides full data backup at half the failure rate of a normal drive, but at the
cost of reducing the total capacity of the raid to that of a single drive. RAID 1 is among the most secure forms
of memory storage available.
In addition, for RAID 1 you may enable Fast Synchronizations. This is a recommended feature that is only
meaningful in RAID 1 architectures. Fast synchronizations will come at a very slight cost to overall access
speeds, a speed cost that in nearly all cases is negligible. Click Apply to implement. To read more about Moxa’s
fast synchronization technology, see Chapter 10, Enabling Fast Synchronizations.