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New Hall of Fame Member-Peter PAluch

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UCS M5 RAID

Hello

I'm wondering why Cisco recommends RAID 5 for the BE7H-M5-K9 model. I know there is a larger amount of space, verses RAID 10, for example, but the performance increases in RAID 10 over 5 is dramatic. 

If we were to switch to RAID 10, is that still supported under the TRC?

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Hall of Fame Cisco Employee

Re: UCS M5 RAID

No, the RAID is part of the TRC specs

 

  • For TRCs using DAS storage, includes specification of required RAID configuration (e.g. RAID5, RAID10, etc) - including battery backup cache or SuperCap.

https://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/uc_system/virtualization/collaboration-virtualization-hardware.html

 

If you choose to change it, you lose the TRC support level and go to UC on UCS spec based.

HTH

java

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Contributor

Re: UCS M5 RAID

Understood, but what is the reasoning behind the RAID 5 verses 10? I asked our account team and we never got a straight answer. Is it purely because the write level is good enough for UC products? Seems like faster HDD would speed performance, upgrades, etc.


Hall of Fame Cisco Employee

Re: UCS M5 RAID

You'd need to ask your SE/AM to reach out to the team that is in charge of UC on UCS and UC virtualization so they can provide the technical answer and the reasoning behind that choice, assuming it's something they can share.

HTH

java

if this helps, please rate
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Re: UCS M5 RAID

I had a similar “but why?!” expression about not supporting RAID 6 since it offers better protection from a read errors during a rebuild from parity. The answer I got was that every product team that supports the TRCs have to test every hardware variation to certify it - that’s the whole point of TRC model. “Min-spec” continues to be the long-term goal/dream and we’re most of the way there: non-TRC is supported so long as you only expect Cisco to support their app and not the full stack
Contributor

Re: UCS M5 RAID

Account team got me this response. RAID 5 is rough from a risk standpoint, i.e. one failed disk kills it all, not to mention RAID 10 has performance gains far beyond RAID 5 (and I don't need 6TB of space with RAID 5 let alone 3.6TB with RAID 10, but regardless, here it is.

Subject: RE: RAID Configuration for M5

Specific to appliances and TRCs...those are targeting voice/video admins with low skillset and low opinion level on HW BOM.
We also have to balance a number of (contradictory?) tradeoffs

1. "support" / how many different RAID configs across the set of TRCs (affects TAC MTTR et. al.)
2. Validating / maintaining performance for new SW release or new HW generation (including "qualification lag")
3. Usable GB space (runtime vs. for TRCs that are also appliances ... size of factory preload)
4. Latency and IOPS performance (big deal as so many of our apps are real-time and IO-driven)
5. Fault tolerance (with assumption of redundant VMs running redundant HW)
6. Ease of failed disk replacement and other customer/partner procedures (remember...voice/video persona not DC persona which is different)
7. Net HW cost vs. Customer willingness to pay

We actually used RAID10 in the 1st-generation Small TRC (C200 M2 TRC#1) with cheap SATA disks.
But in M3 and beyond, RAID5 became a better option in terms of ticking off more boxes above.

"Server/storage/DC persona admin" types dislike RAID5 and will debate what is a "better" or "best" configuration. Usually they prefer additional hot standby disks, RAID6 or RAID10.

If doing specs-based-infra, use whatever RAID you want as long as it meets our min specs around HCL, latency, GB, IOPS.
But we don't test on RAID6/10 nor do we provide prescriptive BOMs, so we don't make the same promise level as we do on our TRCs.
Should not be a surprise, but freaks out risk-averse customers.

If doing prescribed-infra, i.e. a TRC or a BE6K/7K appliance, then assumption is you are not opinionated on the HW BOM, and we've standardized on RAID5 for above reasons.





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