HP 273914-B21 HP Smart Array Controller technology, 3rd edition - Page 20

The HP 650 mAh P-Series battery has the same form factor as previous versions and extends battery life up to 48 hours before recharging is necessary. Battery replacement HP Smart Array controllers include serviceable battery packs that allow tool-free battery pack replacement with no need to replace either the Smart Array controller or the detachable cache module. Alternatives to battery replacement If it is not possible or desirable to replace the batteries, administrators have three options to disable write-back cache and avoid losing critical data: 1. The ACU provides a method for adjusting the read-and-write cache ratio to 100 percent read cache. 2. The ACU provides a method to disable the array accelerator for each logical drive, which disables both read-ahead and write-back cache. 3. Administrators can replace an existing RAID controller with a newer Smart Array controller model. NOTE: If the write cache is turned off, some write performance degradation may occur. For more information about Smart Array controller battery configuration and specifications download the "HP Smart Array Controllers for HP ProLiant Servers User Guide": http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01608507/c01608507.pdf?ju mpid=reg_R1002_USEN Flash-backed write cache HP introduced the flash-backed write-cache (FBWC) system in the fourth quarter of 2009 (Figure 7). 20