LSI MegaRAID User Manual
LSI® MegaRAID® LSIiBBU08
Intelligent Battery Backup Unit for 6Gb/s MegaRAID
SAS Controller Cards
Higher Ambient Temperature Tolerances and Increase Serviceability
The LSIiBBU08 can tolerate higher ambient temperatures around the battery backup unit as
compared to the previous generation battery, with tolerances of up to 55°C versus 45°C for
ambient cell temperature. There is also a remote mount option available which allows
customers who have limited chassis space or a constrained thermal environment to reposition
the battery backup unit away from the RAID controller card for cooling purposes.
A lower temperature environment will generally help prolong the service life of a battery
backup unit, while high temperatures and extreme conditions will shorten the battery life. For
LSIiBBU08
Key Features:
Helps protects integrity of cache in the
event of power or server failure
Higher maximum ambient temperature
tolerance than previous generation battery backup units
Multiple modes of operation and retention
times
Transparent and shorter learning cycles
For use on all existing 6Gb/s MegaRAID
controllers
Customize mounting location in chassis
with remote mounting options
example, if the battery is set to a 12-hour DRT and 45°C mode, it may not require replacement
for the life of the RAID controller1. However, using a 48-hour DRT and 55°C mode with your
battery may cause a situation where the battery requires replacement after the rst
year of use2.
Multiple modes of operation and retention time
The LSIiBBU08 allows for multiple modes of operation, which let the user select a shut-o
data retention time (DRT) of 12, 24, or 48 hours with associated operating temperatures, learn
cycles, and estimated service lives. The MegaRAID controller rmware will use the LSIiBBU08
until it calculates that the battery can only guarantee cache data for the selected period of
time in the event of power loss to the server. With previous generation MegaRAID batteries,
there was only one mode of operation with a retention time of 72 hours. By oering these
multiple modes of operation, the LSIiBBU08 provides the exibility to select the optimum DRT,
performance based on cache policy, and maximum operating temperature that best ts their
specic application and environment.
Product Brief
1. Life of the controller is estimated at three years based on
standard warranty
2. Estimated Calculation based on; 1GB (5 chips) DDR2 and one
1500 mAh Lithium ion cell, individual results may vary.
3. Based on internal calculations regarding estimated battery life
and losses over time, individual results may vary.
Note: BBU warranty is still one year for all modes of operation.
LSIIBBU08 Mode 1 Mode 2 Mode 3 Mode 4 Mode 5 LSIIBBU07
Data Retention
12 Hrs 12 Hrs 24 Hrs 48 Hrs 48 Hrs 72 Hrs
Time (DRT) 2
Transparent
P P P X X X
Learn Cycle
Op Temp (Charg-
45oC 55oC 45oC 45oC 55oC 45oC
ing Temp)
Estimated service
3
life
5 years 3 years 3 years 3 years 1 years 1 years
Product Brief
Transparent and Shorter Learn Cycles
The battery learn cycle is the process where MegaRAID rmware recalibrates the battery gas
gauge with respect to the battery’s chemical capacity so that controller can decide whether or
not the battery can maintain the controller cache for the selected period of time (DRT) in the
event of a power failure. The battery learn cycle partially discharges and then fully charges the
battery backup unit.
With the LSIiBBU08, if the user requests a limited DRT of 12 or 24 hours, the controller will
continue to work in write-back mode during the discharge and recharge learn cycle. In the
event of a power failure during this learn cycle, the controller is designed to accommodate
that there is still enough energy left in the battery to provide the selected retention time (12 or
24 hours). Because the learn cycles can be performed as needed by the BBU without impact to
the write cache policy or performance, this is called a transparent learn cycle.
During the learn cycle in 48-hour DRT modes, the controller is forced to a write-through cache
policy for the duration of the discharge/recharge process, as the Relative State of Charge
crosses the boundary where the stated retention time cannot be maintained. This cache policy
writes the data directly to the disk and helps protect against data loss during a potential power
loss. While this is similar to the existing learn cycle process for the LSIiBBU07 with a 72 hour
DRT, it does allow for much shorter learn cycles. Typically, the LSIiBBU08 only takes 3-4 hours to
discharge and recharge the battery to capacity, versus an 8-10 hour process required with the
LSIiBBU07 due to periodic deep discharges.
No Change To Cache Policy
3 - 4 Hour Learn Cycle
LSIIBBU08
Mode 4 & 5
Learn Cycle
WBWT
LSIIBBU08
Mode 1, 2, 3
Learn Cycle
— Yes Yes
Cache Policy
Discharging Yes (37%) Yes (37%) Yes (90%)
Relaxation Yes Yes Yes
Charging Yes (37%) Yes (37%) Yes (90%)
WTWB
— Yes Yes
Cache Policy
3 - 4 Hour
Learn Cycle
LSIIBBU07
Learn Cycle
8 - 10 Hour
Learn Cycle
For more information and sales oce locations, please visit the LSI website at: www.lsi.com
North American Headquarters
San Jose, CA
T: +1.866.574.5741 (within U.S.)
T: +1.408.954.3108 (outside U.S.)
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Copyright ©2013 by LSI Corporation. All rights reserved. > 1213
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