topic Re: ML380 G6 SmartArray P410i cache module - replace with flash-based so that no battery is required in ProLiant Servers (ML,DL,SL)

ML380 G6 SmartArray P410i cache module - replace with flash-based so that no battery is required?

BOYAN BIANDOV — Wed, 14 Feb 2018 16:25:04 GMT

Hi everyone,

This is in context of ML380 G6. Integrated SmartArray P410i controller with a battery baked-up stock cache module -- I would like to replace the stock battery-backed 512M module with a flash-based one so that no battery is required any longer?

Problem is the maintanence guide of DL380 G6 doens't list the part number of flash based modules compatible with P410i

Is anyone running the newer flash based backup modules with this controller and what is the part number of the flash mased module that you chose to run with your P410i?

Thank you

Re: ML380 G6 SmartArray P410i cache module - replace with flash-based so that no battery is required

krasinka1409 — Wed, 14 Feb 2018 17:05:15 GMT

Hi,

the part numbers are the same as those for the p410 PCI controller and are listed here:

https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c01682458

Even if you upgrade to FBWC module, you will still need a capacitor - "super capacitor module assembly "

Re: ML380 G6 SmartArray P410i cache module - replace with flash-based so that no battery is required

BOYAN BIANDOV — Wed, 14 Feb 2018 18:01:50 GMT

@krasinka1409 Thanks so much for the quick reply. You bring up a good point - I was under the impression that if one uses FBWC module then no battery/capacitor will be required since this is a flash backed cache module. Is that not the case?

My objective is to do away with battery/capacitor on P410i - is that not possible at all even with flash backed cache module?

Thank you

Re: ML380 G6 SmartArray P410i cache module - replace with flash-based so that no battery is required

krasinka1409 — Wed, 14 Feb 2018 18:15:39 GMT

Hello Boyan,

actually this is not the case, you will still need a capacitor. BBWC and FBWC cache modules do both require a battery module. The differance between the battery and supercap is the technology. Here some detailed information about it, I found on web:

While batteries and capacitors have similarities, there are several key differences.
The potential energy in a capacitor is stored in an electric field, where a battery stores its potential
energy in a chemical form.
A capacitor is storing the electrical energy directly on the plates so discharging rate for
capacitors are directly related to the conduction capabilities of the capacitors plates.
A capacitor is able to discharge and charge faster than a battery because of this energy
storage method also. The voltage output of a supercapacitor declines linearly as current flows.

Flash-backed write cache
HP introduced the flash-backed write-cache (FBWC) system in the fourth quarter of 2009. The FBWC uses
flash devices to retain cache data and super-capacitors (Super-caps) instead of batteries to provide power
during a power loss. A BBWC must provide power during the entire power loss, while a FBWC only needs
to provide power during the time to backup from DRAM to flash. The FBWC offers significant advantages
over the HP Battery-backed write-cache (BBWC) system. Since the FBWC writes the contents of memory to
flash devices, there is no longer a 48-hour battery life limitation, and the data posts to the disk drive on the
next power up.

You may also check out the "Smart Array Controller Technology" User Guide here:

https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c00687518

You may use your controller with the FBWC only, wthout installing a capacitor, but this would cause some limitations of the controller features (raid extension, migration etc) and reduced performance.

Best Regards :-)

Re: ML380 G6 SmartArray P410i cache module - replace with flash-based so that no battery is required

BOYAN BIANDOV — Sun, 19 May 2019 03:30:50 GMT

@krasinka1409 Should've said Thanks back then. Yah no escape, one way or another I needed to have a little pig tail with wires hooked to the module and that's just life. Thank you for the detailed compare/contrast between the 2 technologies. I always hated the 48 hour thing and couldn't realize it had to do with simple depletion of the battery :)