Oracle Video server, Manual

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Oracle Video Server (OVS)
2-8 Introducing Oracle Video Server
The MDS supports striping on a volume-by-volume basis. In a striped volume each
file is striped across all the volume’s disks. To write a file to a striped volume, the
MDS writes a stripe on each of the volume’s disks beginning with the first. If the
file requires more space than a single stripe on each disk in the volume, the MDS
writes another stripe to each disk beginning with the first. The MDS continues to
write stripes across all the volume’s disks until the entire file has been written. The
shaded area in
Figure 2–3 shows a single stripe on each disk in a volume.
Figure 2–3 A striped volume
Striping is transparent to the user and a striped file appears logically as one
contiguous sequence of bytes.
RAID (Redundant Arrays of Inexpensive Disks) Protection RAID protection
means storing data redundantly so it remains accessible in the event of a disk
failure. The RAID protection implemented for the MDS is similar to hardware-
based RAID protection but also guarantees on-time delivery even if a disk or
controller fails. RAID is similar to disk mirroring, but uses less space for redundant
data. Together, striping and RAID offer tremendous performance benefits with a
high degree of reliability.
The MDS supports RAID protection on a volume-by-volume basis. If RAID
protection is enabled for a volume, the disks in the volume are divided into RAID
sets. The number of disks in each RAID set is called the RAID size. The RAID size
must be consistent across all RAID sets in a volume, so the number of disks in a
volume must be a multiple of the RAID size.