User`s guide

Document Number: MAN-000SR5-000 Revision 1.40
In exchange for low overhead necessary to implement protection, Parity RAID degrades performance for all
write operations. The parity calculations for Parity RAID may result in write performance that is somewhat
slower than the write performance to a single disk.
Concatenated
The Concatenated mode combines multiple disks or segments of disks into a single large volume. It does not
provide any data protection or performance improvement but can be useful for utilizing leftover space on
disks. Concatenation allows the segments that make up the volume to be of different sizes.
Just a Bunch of Disks (JBOD)
The JBOD is a virtual disk that can either be an entire disk drive or a segment of a single disk drive. JBOD is
the Contiguous configuration option when creating RAID Groups (or sets) in the SATARAID5 Manager
utility.
RAID Volume Status
A RAID volume can be in any one of the following statuses.
Status Meaning
Good All disks are currently functioning as normal.
Reduced
For RAID levels that provide data protection, one or more disks have failed but
the data is still available via the RAID algorithms. The failed disk should be
replaced as soon as possible to avoid loss of data.
Rebuilding
A failed disk drive has been replaced and the data is being regenerated on the
replacement disk. When complete, the RAID Group will return to Good status.
Resynchronizing
An error has occurred and requires that the RAID algorithms be regenerated on
this RAID Group. When complete, the RAID Group will return to Good status.
Failed
One or more disks have failed and RAID algorithms can no longer regenerate
the data. The minimum number of failures required to reach this state depends
on the RAID level:
• RAID 0, Concatenated, JBOD/Contiguous: Single-disk failure.
• RAID 1, 5, 10: Two-disk failure.
For increased versatility, the SATARAID5 software allows individual disks to be divided into smaller
segments that can then be combined into different volumes. As an example, if a user has one set of data that
must be protected at all costs, another set of data that should be protected at reasonable cost, and another set
that needs no protection at all, the user can divide three disks into segments as shown in
Figure 1.
SATARAID5 Management Software User's Guide
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