Specifications

Escala Tower PL & S, E, T System Hardware
Chapter 3: External Storage and SAN Subsystems 26/116
9es3s1c3.doc
Rev 5.9
02/12/2003
The usable cache size is computed as described in the next table:
1 SP 2 SP
Raw memory per SP M M
Write cache 0 W < M
Read cache M 2 x (M – W)
Total M W + 2 x (M – W)
M is the amount of available raw memory per SP
W is the value configured for the write cache size.
Because of the mirroring, the usable write cache is not multiplied by the number of SPs.
2.1.5.5. Summary of high availability features
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dual port disks
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dual loops / LCCs
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dual Power supply with independent power cords
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redundant fans.
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no electronics in the chassis or back plain
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all active components are hot plug
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RAID protection
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redundant SP
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mirrored write cache.
2.1.5.6. Supported Fibre Channel topologies
The DPE supports various fibre channel topologies:
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point to point (connection with a direct cable)
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loop (connection to a fibre channel hub)
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fabric (connection to a fibre channel switch)
2.1.5.7. RAID features
The RAID features of the DPE are:
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RAID 0, RAID 1, RAID 1/0, RAID 3, RAID 5 and “individual disk” modes support
LUN type: Possible number of disks in the RAID volume:
RAID 0: 3 to 16 disks
RAID 1: 2 disks
RAID 1/0: 4 to 16 disks (must be an even number)
RAID5: 3 to 16 disks
All disks within a RAID volume must have the same capacity, otherwise, disk storage space is
wasted.
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Any combination of RAID levels can exist in the same subsystem