On Nov 15, 2012, at 15:32 , Ken Teh wrote:

> Thanks Nico!
> 
> Anyone else want to comment?  I'd like to hear people's opinions about such
> issues.  When one is not 100% involved in such efforts, it helps to have input
> from people who are or have dealt with similar issues.

Just like Graham's, our experience with (mostly OEM'ed) LSI cards is not bad at all. And we've been running many of them for years. Mail me in private for suggestions what to avoid like the plague - including one of Nico's favorites.

> On a related note, this is probably the last disk array I want to put together
> myself. I discovered to my exasperation that I needed enterprise class drives
> because of the TLER effect.  The next disk array I buy will be a ready-made
> appliance.

Wise indeed. No need to go to the extreme of buying appliances though. Get a complete system, including the drives (!), cables etc., from a major vendor, certified to run TUVEL. Apply firmware updates as soon as you can (purchase hardware that's been on the shelf for at least a year, preferably longer, if you want to keep those to a minimum). There's still a 1% chance you'll experience major grief. But that's a lot better than what you're asking for when sticking some desktop drives into an enclosure and hoping for the best.

- Stephan

> On 11/14/2012 08:58 PM, Nico Kadel-Garcia wrote:
>> On Wed, Nov 14, 2012 at 12:37 PM, Stephen John Smoogen <[log in to unmask]> wrote:
>>> On 14 November 2012 10:20, Ken Teh <[log in to unmask]> wrote:
>>>> The common thread is I/O to a MegaRAID raid5 device.  Which is cause for
>>>> concern since the primary function of both machines where I've encountered
>>>> this problem is file-serving.
>>>> 
>>>> Perhaps I am just unlucky and have 2 bad MegaRAID cards in a row.  I'm
>>>> trying
>>>> to understand this better, figure out if I am doing something wrong.
>>> 
>>> Well there are a couple of issues this could be:
>>> 
>>> 1) You are asking more than the MegaRaid is meant to do... it may be
>>> running out of cache, or other resources.
>> 
>> My experience with MegaRAID has been *horrible*. Poor driver
>> compatibility, awkward and destructive firmware, and deceitful
>> specifications only start the list of horrible failures. Their best
>> technological use is as doorstops.
>> 
>>> 2) The megaraid is still rebuilding its array beneath and you are
>>> hitting a locking problem because it hasn't finished what it needs to
>>> do before you ask it to do something else (really sort of #1).
>>> 
>>> Most of the time you will need to install the proprietary Megaraid
>>> tools to see what is going on under the disks to find out.
>> 
>> See above: good luck getting those tools working!
>> 
>> Every hour you spend waiting on those things to come to their senses,
>> or trying to debug them, is an hour wasted on problems that may not
>> ever be solved by your efforts. I encourage you to replace them with a
>> better quality manufacturer: Adaptec makes very solid, not too
>> expensive controllers, and Rocketport remains the cream of the crop.
>> 

-- 
Stephan Wiesand
DESY -DV-
Platanenenallee 6
15738 Zeuthen, Germany