Specifications

Escala Tower PL & S, E, T System Hardware
Chapter 3: External Storage and SAN Subsystems 25/116
9es3s1c3.doc
Rev 5.9
02/12/2003
2.1.5.4.5. Cooling Fans
DPE enclosures are equipped with a drive fan pack that cools the disk modules. DPE enclosures also
include an SP fan pack that cools the SPs. Any type of fan pack contains three fans. If a fan fails, the
speed of the remaining fans increases to compensate. If needed, a fan pack can be removed for
exchange operation while the storage system continues to operate (the exchange operation, however,
must not exceed two minutes, otherwise disks and SPs will shut down).
2.1.5.4.6. Disk drives
DPE enclosures use the same disks as the DAE and iDAE enclosures. The minimum number of disks
per DPE enclosure depends on the number of LCCs and SP. The maximum is always 10 disks, but one
or two DAE can be chained to increase the capacity of the array:
Minimum
(DPE enclosure)
Maximum
(DPE enclosure)
1 SP / 1 LCC 5 10
2 SP / 2 LCC 9 10
Disks are formatted with 520 bytes per sectors.
2.1.5.4.7. Memory
The available memory depends on the SP model.
Size
(MB)
4500 256, 512, 1024
5700 64, 128, 256, 512
A few amount is reserved to store the LIC (Licensed Internal Code) running on SPs. The exact size
depends on version, and is around 12 MB. The rest of the cache is available for read cache, or write, or
a mixture of both, to improve performances of the subsystem. To ensure data consistency in case of
failure,
the write cache is always mirrored
, and the following hardware configuration must be used:
•
Two SPs per DPE
•
Two power supplies and two LCCs in the DPE and in each DAE
•
Disk slots 0 through 8 of the DPE enclosure must be populated.
•
One SPS with a fully charged battery (two SPSs provide higher availability)
•
Identical cache memory in both SPs.
It is not possible to use write caching without mirroring across SPs and without the hardware
configuration described above. For example, it is not possible to configure a write cache on a DPE
with a single SP.