Eye on Blades Blog: Trends in Infrastructure
Get HP BladeSystem news, upcoming event information, technology trends, and product information to stay up to date with what is happening in the world of blades.

Information on DDR3 memory lock-step technology

Lots of questions about advaced memory protection and capabilities with the latest HP ProLiant G6 server announcement.

HP BladeSystem Announcing today page: www.hp.com/go/bladesystem/news

How does DDR3 memory work and one of the new features is memory lock-step capabilities?

Lock-step mode is an advanced memory protection feature supported in many of the G6 servers announced yesterday (3/30/09), including the BL460c G6 and BL490c G6.  It takes two of the Xeon 5500 processor's three memory channels and runs them together, which enables 8-bit error correction instead of the 4-bit correction you get in normal Advanced ECC (non-lockstep) mode. PositivesSmiley Sad1) Achieves the same level of protection as ChipKill*, so there are some additional scenarios in which the system can correct memory errors.   Negatives: (1) You have to leave one of the three memory channels on each processor un-populated, so you cut your available number of DIMM slots by 1/3.  (2) Performance is measurably slower than normal Advanced ECC mode.(3) You can only isolate uncorrectable memory errors to a pair of DIMMs (instead of down to a single DIMM). Lock-Step mode is not default operation; it must be enabled in RBSU. We don't know how many customers will want to use it.   *Normal" ECC can correct single-bit errors and detect double-bit errors.  HP's term "Advanced ECC" means that the server corrects single-bit errors, detects multi-bit errors, and corrects some multi-bit errors that occur on the same DRAM.   Advanced ECC is not the exact same thing as ChipKill, which is an IBM term.   In some but not all scenarios, Advanced ECC offers the same protection as ChipKill.
We are updating the "HP Advanced Memory Protection technologies - Technology Brief" to include info about new features like this.http://h18004.www1.hp.com/products/servers/technology/whitepapers/index.html?jumpid=servers/technolo...

Anonymous | ‎01-28-2010 04:53 PM

i have full information of ddr3 technology.

nandini kalra | ‎10-19-2010 08:17 AM

with reference to the positive point detailed above, does it imply that Chipkill=Lockstep when only level of protection is being considered?

kalamworld | ‎07-29-2011 03:12 AM

It’s great that you have published such knowledge. I just hope these are all reliable. It would be better if you also include in your page the references that you are using. Thanks!

rishuaggarwal | ‎12-09-2012 07:49 AM

IS there any one .who can explain me  wht lockstepping is ?????  how lockstepping works in G6,G7 server and G5 as well .....

Showing results for 
Search instead for 
Do you mean 
About the Author

Follow Us
The opinions expressed above are the personal opinions of the authors, not of HP. By using this site, you accept the Terms of Use and Rules of Participation.