Dual memory dimms in a Cisco 3845 router

[joseph.a.marino]

We still have Cisco 3845 routers in our infrastucture, each router has a single 512 chip. We are starting to have memory chip failures, we have spares and that gets us by but my question is - if I equip a Cisco 3845 with two 512 chips and either chip goes bad will the device continue to operate on the one good 512 chip?

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Show Ver:

Cisco IOS Software, 3800 Software (C3845-ADVIPSERVICESK9-M), Version 15.0(1)M8.1, MAINTENANCE INTERIM SOFTWARE
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Fri 30-Mar-12 02:50 by prod_rel_team

ROM: System Bootstrap, Version 12.4(13r)T11, RELEASE SOFTWARE (fc1)

XXXXXXXXXXX uptime is 11 weeks, 20 hours, 17 minutes
System returned to ROM by power-on
System restarted at 11:28:02 EST Thu Feb 3 2022
System image file is "flash:c3845-advipservicesk9-mz.150-1.m8.1.bin"
Last reload type: Normal Reload

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Cisco 3845 (revision 1.0) with 223232K/38912K bytes of memory.
Processor board ID FTX1213A3JM
2 Gigabit Ethernet interfaces
3 Serial interfaces
64 terminal lines
1 Virtual Private Network (VPN) Module
DRAM configuration is 64 bits wide with parity enabled.
479K bytes of NVRAM.
126976K bytes of ATA System CompactFlash (Read/Write)

License Info:

License UDI:

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Device# PID SN
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*0 CISCO3845-MB         XXXXXXXXX

Configuration register is 0x2102

[marce1000 · Accepted solution]

 - No , second chip offers expanding capabilities for memory , not memory-failover.

 M.

[Joseph W. Doherty]

Cannot say with 100% assurance, but as @marce1000 notes, a second memory slot usually would only provide memory expansion, not any kind of memory redundancy.

Further, BTW, as a side note, often additional memory chips have to be "like" what's already installed, i.e. capacity and often, I recall, speed too.

Lastly, besides additional memory capacity, additional memory chips often allow faster access as access can be spread across multiple banks of memory.  (I doubt this feature, if implemented, would make a noticeable difference on most network devices.)

Some systems are designed to use memory chips without any kind of error detection, some are designed to detect basic errors (like a single flipped bit) and some are designed to use error correcting memory (ECC).  Don't recall if any systems are designed to use more than one kind of the forging memory types or what Cisco generally uses in their network platforms.

[joseph.a.marino]

Thank you both for a quick reply, its appreciated!!

[joseph.a.marino]

I thought that woudl be the case, thank you for your reply!

[balaji.bandi]

i can not remember the how many slots...but the one you looking not going to work.