Whitepaper: ReadyNAS FlexRAID Volume Optimization Guide

Whitepaper:
Optimizing Your ReadyNAS® OS Flex-RAID Volumes
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2. RAID Groups and RAID Levels Explained
RAID is short for redundant array of independent disks.
RAID is a storage technology that balances data protection,
system performance, and storage space by determining
how the storage system distributes data. Different ways of
distributing data are standardized into various RAID levels.
Each RAID level offers a tradeoff of data protection, system
performance, and storage space. For example, one RAID
level might improve data protection but reduce storage
space, another RAID level might increase storage space but
also reduce system performance. RAID is not a backup.
RAID groups organize large volumes so that the OS
can distribute I/O across the groups. This can improve
I/O performance. For example, the OS will write some
operations to one RAID group, and then to a second. The
performance is like being able to write to two independent
drives, but with the capacity and management efficiency of a
single logical drive.
Below is a table containing the various RAID levels
supported by the ReadyNAS and recommended number of
drives for each RAID level.
RAID Min. # selected drives
Max. # of drives for single
volume (RAID group)
Redundancy
(# of drive failure
tolerance)
Notes
JBOD 1 1 0
Selecting JBOD will remove all disk
protection in the event a disk fails.
1 2 2 1
5 3 6 1
Selecting more than 6 disks is not
recommended for the performance
and reliability of the ReadyNAS.
6 4 15 2
Selecting more than 15 disks is not
recommended for the performance
and reliability of the ReadyNAS.
10 4 4 1
50 6 6 (in a single RAID group) 1 per RAID group
Selecting more than 10 RAID
groups is not recommended for the
performance of the ReadyNAS.
60 8 15 (in a single RAID group) 2 per RAID group
Selecting more than 4 RAID groups
is not recommended for the
performance of the ReadyNAS.
Remaining Disks Global Spare
3. How We Tested
The test environment consisted of four Windows 10 computers with 10-Gbps Ethernet interfaces connected to a NETGEAR
XSM7224S switch, and one ReadyNAS RR4312 system with twelve 1TB hard disk drives. The tests used workloads defined for
and run by the test application fio. Random reads, random writes, sequential reads, and sequential writes used a 4K byte block
size. Drag and drop tests used a 128K block size. Separate tests were run against iSCSI targets and SMB file systems. Tests
were repeated with SSDs configured in using ReadyTIER. High tier and low tier environments were also compared. For more
information about ReadyTIER, see the Overview of ReadyTIER section.