The Real Story about IBM’s blades

January 2007.  There are important differences that you should consider when evaluating HP and IBM blade servers.  HP has designed the HP BladeSystem c-Class with a look to the future, while IBM’s blade designs are burdened with the legacy of the past.

Here are some facts you may not know about IBM blades -- they’re ones IBM hopes you don’t find out.  Please consider the following.

Fact 1: HP tests found that the HP BladeSystem c-Class is more energy efficient, requires less airflow, produces less noise, and has more accurate power management systems than IBM BladeCenter H.[1]

Fact 2: The processors on the IBM HS21 blade server are mounted upstream of the memory and hard drives.[2]  IBM admits, “this resulted in undesirable preheating to all downstream components, namely memory and hard drives.”[3]

Fact 3: The IBM blade server HS21 does not support hot pluggable drives without an additional expansion unit, which reduces blade density by half.[4]

Fact 4: The base IBM blade server, HS21, is limited to just four DIMM  (dual in-line memory modules) slots without adding an additional memory expansion unit.[6] 

Fact 5: The base IBM blade server HS21 does not have an option of a battery-backed write cache without adding an additional expansion unit.[7] 

Fact 6: When configured with hot-plug drives and 8 DIMMs to match HP, the IBM HS21 blade server takes up three blade slots, resulting in just 4 servers per IBM BladeCenter H enclosure vs. 16 HP BL460c servers per HP BladeSystem c7000.

Fact 7: IBM’s highly touted backwards compatibility between BladeCenter and BladeCenter H[9] comes with limitations, and doesn’t hold up in all cases.

• The IBM blade server HS21 with Intel Xeon 5160, 3 GHz dual core processors are only supported on the BladeCenter H enclosure, not the BladeCenter.¹⁰

• IBM states that the  blade servers LS21 and LS41 using the 95 watt version of the AMD Opteron processor  (LS21 - 3AY, 6AY & LS41 - 3AY, 6AY, 3BY, 6BY) are designed for use in the BladeCenter H chassis. When these blade servers are placed in a BladeCenter or BladeCenter T chassis, the processors run at “n-2” speed which IBM says results in a speed reduction of 400 MHz in most cases.¹¹

• The JS21 blade server with the 2.5 GHz dual core PowerPC970 processor is throttled to run at 2.3 GHz when installed in the BladeCenter or BladeCenter T.  The JS21 blade server with the single core 2.7 GHz PowerPC970 processor is throttled to run at 2.6 GHz when installed in the BladeCenter or BladeCenter T.¹²

 • 4X Infiniband is only available in the BladeCenterH.¹³

Fact 8: The IBM BladeCenter H 4X Infiniband bandwidth is 10 Gb/s[14], one-half of the bandwidth the HP BladeSystem c-Class delivers at 20 Gb/s.[15]

Fact 9: IBM’s onboard diagnostics, called Lightpath Diagnostics, offers only LED displays but no detailed, intuitive and interactive LCD display like HP’s Insight Display.[14]

Fact 10: IBM has no comparable offering to HP Virtual Connect.[15]

HP Virtual Connect streamlines blade server provisioning and management.

Bottom-line:   The above comparisons are only the beginning.  HP BladeSystem c-Class infrastructure offers flexibility and scalability, and requires no compromise. It takes advantage of the best technologies across HP – innovations that make everything from NonStop servers to HP printers the best in the industry – and brings them together to fundamentally improve how customers buy, manage and use their computing resources.

To find out more about the HP BladeSystem, see: http://h71028.www7.hp.com/enterprise/cache/80316-0-0-0-121.html

¹  For test results and details see:  “The Real Story about IBM’s BladeCenter power claims”  http://h71028.www7.hp.com/ERC/cache/133820-0-0-0-121.html?ERL=true

²  See visual tour link at http://www-03.ibm.com/servers/eserver/xseries/tours/blade_tour_05/blades_shell_05.html

³ http://researchweb.watson.ibm.com/journal/rd/496/crippen.html, “This resulted in undesirable preheating to all downstream components, namely memory and hard drives. Cooling with preheated air presented extreme cooling challenges for the hard drives. Careful balancing of airflow and life prediction tests at given air temperatures was required. For higher-powered processor blades, the processor blade front allows some fresh air to bypass the processors, providing much-needed local cooling to hard drives..”

⁴ http://www-03.ibm.com/systems/bladecenter/hs21/features.html

⁵ IBM Redbook:  http://www.redbooks.ibm.com/redpapers/pdfs/redp3581.pdf, pDF page 43 states, "When completed, line the SCSI Expansion Unit directly on top of the blade server so the pins could snap directly into the slot where the terminator used to be. That will make the blade server a little wider and that means two slots will be used in the IBM Eserver BladeCenter, so every Expansion Unit takes away a slot for a blade server."

⁶http://www-03.ibm.com/systems/bladecenter/hs21/features.html

⁷ http://www-03.ibm.com/systems/bladecenter/hs21/features.html

⁸ http://h18004.www1.hp.com/products/servers/proliant-bl/c-class/460c/benefits.html

⁹http://www-03.ibm.com/systems/migratetoibm/hearit.html, “All three [BladeCenter, BladeCenter H and BladeCenter T] are compatible with the same set of blades and switches, and this interoperability enables customers to choose a combination of BladeCenter products that best meets their needs

¹⁰ System x Reference, dated 12 Dec 06, http://www-03.ibm.com/servers/eserver/education/cust/xseries/xref/usxref.pdf  PDF page 71

¹¹ Note 1:  http://www-03.ibm.com/servers/eserver/xseries/cog/bchassis8677/bchassis8677aag.html

¹²  IBM Redbook, http://www.redbooks.ibm.com/redpapers/pdfs/redp4130.pdf , page 8 table 1-7
  
¹³  http://www-132.ibm.com/webapp/wcs/stores/servlet/CategoryDisplay?categoryId=4611686018425093905&storeId=1&catalogId=-840&langId=-1

¹⁴http://www-03.ibm.com/systems/bladecenter/switch/switch_infiniband_overview.html

¹⁵http://h18004.www1.hp.com/products/blades/components/infiniband/index.html

¹⁶ See the table http://www-1.ibm.com/support/docview.wss?uid=psg1MIGR-56991

¹⁷ HP analysis of IBM’s offering