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CentricStor - Virtual Tape Library Hardware architecture
The metadata of the logical volumes to be written or read is stored on the 1st RAID system,
as a result of which the usable capacity of this RAID system is reduced by 16 GB.
A CentricStor can contain up to 8 RAID.
The number of cache file systems determines the number of logical volumes available (up
to 500,000). At least one cache file system is required for each 100,000 logical volumes.
The Cache Mirroring Feature (CMF) requires an additional cache file system for possible
recovery measures. Under these conditions the following minimum requirements conse-
quently apply for logical volumes with the standard size of 900 MB:
When larger logical volumes are used (2 - 200 GB, see the section “New system functions”
on page 43), correspondingly more cache file systems can be required. When the Cache
Mirroring Feature (see the page 55) is used, all cache file systems are mirrored to RAID
system pairs and therefore require double the disk resources. The capacity is therefore
reduced by 50%.
2.2.3 FibreChannel (FC)
The entire flow of data between all CentricStor components (ISPs and external RAID sys-
tems) is handled via an internal SAN which can provided with redundancy. It is implemented
by one high-performance FC switch or, if redundancy is provided, by two high-performance
FC switches.
2 FC technologies are available, Multi Mode and Single Mode. In Multi Mode the devices
which are connected via Fibre Channel can be located up to 300 m from each other; in Sin-
gle Mode the distance can be as much as 10 km. The FC controllers used in CentricStor
support bandwidths between 1Gb/s (Gigabits per second) and 4 Gb/s.
2.2.4 FC switch (fibre channel switch)
In the CentricStor models VTA 1500-5000, the entire flow of data between all CentricStor
components is handled by means of an FC switch.
Logical volumes Cache file systems required
100,000 At least 2
200,000 At least 3
300,000 At least 4
400,000 At least 5
500,000 At least 6