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Table 2. IBM Enterprise Storage Server feature comparison (continued)
Feature
Disk drive module (DDM) format
Peer-to-Peer remote copy (PPRC)
(See Notes 2 and 3.)
Concurrent Copy
Extended Remote Copy (XRC)
XRC planned outage
FlashCopy (See Note 3.)
IBM Subsystem Device Driver (see
Note 1 below)
Multi-path locking facility (MPLF)
Multiple allegiance
Parallel-access volume
Notes:
1. See the ESS web site at
www.ibm.com/storage/hardsoft/products/ess/refinfo.htm
for details about host-system adapters supported with the ESS. See the following web site for details
2. This feature requires that you install an ESCON adapter on both the primary ESS and the secondary ESS.
3. The ESS does not support PPRC or FlashCopy on the AS/400.
Table 3 lists the physical features for the ESS.
Table 3. IBM Enterprise Storage Server physical features
Feature
Continuous availability, designed to virtually eliminate
single points of failure or repair (See Note 1.)
Dual-cluster configuration
SSA device adapters
Spare DDM (See Note 2.)
Read/write functions
22
ESS Introduction and Planning
Host Systems with SCSI or
Fibre-Channel Interfaces
Fixed block address (FBA)
Yes
No
No
No
Yes
Yes
No
No
No
Description
v Cluster-processor complex failover
v Device adapter failover
v Concurrent maintenance
v Failover/failback
v Eight cluster processors
v Cache: 6 GB for Models E10 and E20, 8 GB standard
and optional 16 GB for Models F10 and F20
v NVS: 384 MB
Eight serial storage adapter loops (maximum)
v RAID 5 (6+P+S, 7+P)
v RAID reconstruction with spare DDM
v Read/write cache
v Fast-write NVS in storage server
v Maximum sequential bandwidth
– 180 MB/second read
– 140 MB/second write
Host Systems with ESCON
Interfaces
Count key data (CKD)
Yes
Yes
Yes
Yes (MVS operating systems)
Yes
No
Yes
Yes
Yes
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