Question

Safe to Disable cache on a PowerEdge 2800 PERC 4e/Di ?

Asked by: hpcadmin06

We have an out of warranty Dell PowerEdge 2800 server running Win Server 2003 with the following embedded RAID controller: PERC 4e/Di. Here are a few of its specs:

RAID BIOS H435 Build April 23, 2008
PERC/CERC BIOS Configuration utility U827
RAID 5

At boot we get the following RAID Post error message:
"Memory/battery problems were detected. The adapter has recovered, but cached data was lost.
Press any key to continue."

While up and running, we get various blue screens and random OS freezing and crashing.

Blue Screen
A process or thread crucial to system operation has unexpectedly exited or been terminated.
Stop: 0x000000F4 (0x00000003, 0x899A9D08, 0x899A9E6C, 0x8094C6E6)

Through multiple Dell technician phone calls, we arranged for them to send us a replacement battery for the RAID controller. We installed it, let it charge for 24 hours, but we still get the Post error and the random crashing. I have also reseated the RAM DIMM, but the problems persist. We updated the MLB BIOS as well as the PERC firmware BIOS, with the problems still persisting.

Now, we believe that the problem is a bad RAM DIMM on the controller. The documentation for the PERC 4e/Di is hard to find on Dell's website and not very helpful. I found LSI's site a bit more helpful because they give detailed manuals for their controllers, which is the platform upon which dell's PERC controllers are based. All troubleshooting there and in other places on the web all point to the battery or the memory DIMM being the problem. And since we have a brand new battery, we think it is the DIMM.

Here are the specs for the existing memory DIMM:
Samsung Part Number: M393T3253FZ0-CC
256 MB DDR2 PC2-3200R ECC Registered SDRAM MODULE 240pin Registered Module based on 256Mb F-die 72-bit
400MHz; 1R x 8

We would like to simply buy a new one, but apparently this is a very hard part to come by. Dell agreed with our diagnosis (replacing the DIMM) but they no longer carry it. I called around to our local computer shops (Altex and Fry's) and the local ones that sell white label and custom computers- nothing. I also called 4allmemory.com, but they don't carry it. Apparently, the fact that it is "Regsitered" and "DDR2" makes it hard to find.

I cam across the following thread that indicates that i can turn off the cache feature on the RAID controller, which is the only function that uses the DIMM. By doing so, the cache will no longer become corrupted because it's not being used.
http://en.community.dell.com/forums/t/17436588.aspx?c=us&l=en&cs=&s=gen

I mentioned this option to Dell technical support and he wasn't sure if it was safe to do so. He thought I might blow out my entire RAID configuration and force me to recover from backup tapes to a newly initialized and configured RAID volume.

However, through my research on various forums, I've seen people mention that they have turned their cache off as a matter of troubleshooting other issues (I/O speed, ie) which leads me to believe that the setting changing would not kill my configuration.

Does anyone have any experience with this? Specifically, can I change my cache settings within the PERC manager and NOT have to lose all of my RAID configurations (and be forced to format and reinstall)?

Thanks in advanced!

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Asked On
2009-03-10 at 14:27:04ID24217854
Tags

Dell

,

RAID

,

Cache

,

DIMM

Topics

Storage Technology

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Computer Hard Drives

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Computer Servers

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Answers

 

by: AustinDellManPosted on 2009-03-10 at 15:09:42ID: 23852076

Yes you can do this and it is perfectly safe.  The question is; has the loss of cached date caused corruption that is unrecoverable.  If you do disable the Caching, especially on a RAID 5 you will see quite a bit of performance loss as RAID 5 is slow to start with on writes.  If this is not an issue then yes by all means disable the caching on the controller and you will eliminate the problem

Also, it sounds to me that your PERC DIMM is the problem as the battery is only neccesary to preserve cached data when there is a power loss situation.  So if you were not losing power and you were still getting this error I would definatly point at the DIMM.  

If it were my system, I would backup ASAP, and get a new controller.

Let me know if you need directions to disable the PERC Cache policy.  It can be done in the OS with OMSA or thru the BIOS on the controller

 

by: hpcadmin06Posted on 2009-03-10 at 16:34:54ID: 23852701

AustinDellMan, thanks for your thorough reply. And I feel better knowing that disabling and enabling cache is safe.

Answers to your questions:
1. We have not had any power issues, so I agree that the battery is not the issue.
2. Performance lag is to be expected without caching, and that is acceptable foor the short term.
3. We are not sure if the cached data corrupted the RAID configuration, and don't know how to check fo that.

Now we are having difficulty booting into Windows. We get a blue screen either right before or right after the domain login prompt. We can only boot into Windows once er three or four blue screens and restarts. We are very antsy about our data now, and we are doing manual drag copy backups because the system freezes when BackupExec runs. (High RAID load.)

You asked if I knew how to turn off cache... Not sure. We will need to do so in the PERC manager at this point. I found an option in this location:
Objects->Logical Drives->View Parameters->Cache Policy
  Option 1: Cached IO
  Option 2: Direct IO

The setting is currently set to Direct IO. Does this mean that the controller is not using the cache anyway? Meaning the cache is already turned off?

Do you think any of the following will allow us to boot more reliably into Windows:
1. Turning off cache
2. Replacing the DIMM on the controller.
3. Replacing the controller (which is embedded on the riser)

My preference is to replace the entire controller, but that might be a few days off.

Final question...
If we order a new controller (which means riser for this model since it is embedded on the riser), can we simply swap the controller and still maintain the RAID configuration, and keep all my data? Or does replacing the controller mean I'm starting from scratch with my entire RAID configuration?

Thanks again.

 

by: AustinDellManPosted on 2009-03-10 at 18:14:34ID: 23853165

Sounds like you need to run CHKDSK /r from recovery console to try and repair corruption in you file system.  Are you familiar with this process?  

If the system even attempts to boot then your RAID config is fine.  If the config was damaged the controller would tell you that the array is failed or would not list one at all.  I think the dirty cache issue casused NTFS corruption and this is why the system is bouncing all the time.  Run CHKDSK /r from recovery console till it comes back with no errors found, this could mean you need to run it 4 or 5 times.  When it comes back with no errors found try rebooting normally.  Oh yeah, to get to recovery console you will need to load the PERC 4e/Di driver for the OS to communicate with the controller.  Do you have a floopy drive?  If not there is an ISO that you can burn to load the driver into memory.  Let me know.

CNTRL M on post will get you to the Controller BIOS, check the following
Objects, Logical Drive (you will have to do this on each logical drive):
Write Policy: WRTHRU
Read Policy: No Readahead
Cache Policy: Direct IO

This needs to be set on all logical drives to completely disable cache.

Back to swaping controllers.  If you get a new controller,preferably a PERC 4e/DI again, it will give you an NVRAM mismatch error on boot post installing the new controller.  YOu will enter the CNTRL M bios again and import config from the drives.  THis is a seamless process and will not destroy your data.  Also on the current controller under
Ojects, Adapter, Other Adapter Information,
what is the FW VER on the controller?

Check against the dell site and make sure that this is up to date.
http://support.dell.com/support/downloads/format.aspx?c=us&l=en&s=gen&deviceid=6395&libid=35&releaseid=R186634&vercnt=8&formatcnt=0&SystemID=PWE_PNT_P3C_2850&servicetag=&os=WNET&osl=en&catid=-1&impid=-1

Should be 5B2D

 

by: hpcadmin06Posted on 2009-03-10 at 21:09:10ID: 23853889

Again, thanks for these ideas.

We have been running CHKDSK throughout the day, but only when Windows asks us to do so while in its boot process. We'll run it again according to your instructions (from the recovery console and until we get no errors).

In the morning, we will disable the three cache settings. I only found the "Cache Policy" on my own, and I will find and set "Write Policy" and "Read Policy" accordingly. Interestingly, our Cache Policy setting was already set to Direct IO, so I hope the others aren't also already set to disable cache.

Hopefully, fully disabling the cache will stabilize Windows until we receive the new controller.

Finally, we upgraded the firmware for the PERC controller when we began troubleshooting a couple of days ago; in any case, I will check to make sure we are the latest version (5B2D).

More info in the morning...

 

by: hpcadmin06Posted on 2009-03-11 at 08:25:03ID: 23858380

AustinDellMan,

I'm getting conflicting information about disabling the cache. My colleague was on the phone with Dell tech support this morning and they followed up with an email. Quoted from the support rep, "Also you can not disable caching, plus it is the reason that you are having issue with transferring data is because it turned off because of the Dimm."

This rep works in the "Enterprise Expert Center."

He says we can't turn off cache, and you say we can. Any thoughts?

Thanks in advance.

 

by: hpcadmin06Posted on 2009-03-11 at 09:40:40ID: 23859309

Another update: I just got off the phone with a escalated Dell support person and he confirmed what we have been talking about here. So this is my course of action:

1. Order the new controller and DIMM.
2. Disable the cache on the current controller until the new parts arrive.

Will keep you posted.


 

by: AustinDellManPosted on 2009-03-11 at 11:11:24ID: 23860339

The first tech you spoke with must be misinformed.  You can safely disable cache in order to circumvent data corruption due to a faulty DIMM.  Did the escalations manager explain this to you?  Sounds like you are on the right path with getting a new controller and DIMM.  Let me know how it all goes.

Also did you run chkdsk /r till no errors were found, and if so did the OS succesfully boot post this process?

 

by: hpcadmin06Posted on 2009-03-12 at 14:38:53ID: 31556493

Thanks for all of your help. Your information and guidance has been wonderful. I may be back to ask more questions when we receive the parts.

 

by: hpcadmin06Posted on 2009-03-12 at 14:41:57ID: 23873956

Just to followup, yes, we had the latest firmware, and we did run CHKDSK /r until we received no errors (twice). We disabled the three cache settings, and we haven't gotten any errors or blue screens for 24 hours. We have the riser/controller on order from Dell, and the DIMM on order from an aftermarket vendor. When the parts come in, we will have replaced the controller, its battery, and its DIMM. Hopefully this will fully resolve our core issues. Thanks again AustinDellMan.

 

by: AustinDellManPosted on 2009-03-12 at 18:38:43ID: 23875464

Great, let me know when you get your parts and get them installed.  Would love to address any questions that may come up.

 

by: rrablePosted on 2009-06-04 at 04:15:35ID: 24545535

Just went through the exact same issue. cache is now disabled pending arrivial of new memory. Did this solve your issue? Thanks

 

by: hpcadmin06Posted on 2009-06-04 at 08:08:05ID: 24547773

rrable, yes, the new parts solved the problem. I can't be certain *which* part solved the problem, but when we replaced all three, the errors and crashing went away. We replaced the controller (riser), its battery, and its DIMM.  (By the way, I don't think it was the battery because we replace it first, but still had the problems. My guess is that the problem was the DIMM.) Good luck!

 

by: ronlwilliamsPosted on 2009-09-18 at 08:37:32ID: 25367078

I just had the same problem, replacing memory and battery solved the problem.  After 3 attempts to continue and boot windows, the server would lock at "press any key to continue..."  I could not enter RAID config or system setup.  I had another PE 2800 that I moved the drives to temporarily to make an updated backup while waiting on the memory, thankfully my server was still under warranty.  I didn't have any spare memory of that type in house either.

 

by: rwoodhallPosted on 2010-11-30 at 11:37:56ID: 34242038

Having the same problem on my PowerEdge 2800. Followed the steps. Disabled the cache. Ran CHKDSK /R 4 times and now have no errors. However, when I boot up I still get the BSD Stop: 0x000000F4 error. What do I need to do next?

 

by: AustinDellManPosted on 2010-11-30 at 15:57:04ID: 34244259

your filesystem may have been corrupted to the point of no repair.  Have you tried booting the system from Windows media and seeing if it recognizes an OS install?  If it does, you have two options:

1:  Parallel install.  This will allow you to salvage date on the system volume and the restore
2:  Repair install.  If this works then you may get the OS back up and going.

Oh yeah, have you tried FIXBOOT and FIXMBR from recovery console?

 

by: BuildingITCPosted on 2011-07-15 at 09:43:28ID: 36196461

Following the instructions below posted by AustinDellMan did the trick for us on an out of warranty 1850.  Thank you so much!

CNTRL M on post will get you to the Controller BIOS, check the following
Objects, Logical Drive (you will have to do this on each logical drive):
Write Policy: WRTHRU
Read Policy: No Readahead
Cache Policy: Direct IO

20120131-EE-VQP-002

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