Re: reboot - is there a timeout on filesystem flush?

[Gary Greene <ggreene@xxxxxxxxxxxxxxxxxxx>]

> On Jan 7, 2015, at 12:08 PM, John R Pierce <pierce@xxxxxxxxxxxx> wrote:
> 
> On 1/7/2015 11:30 AM, Gary Greene wrote:
>> During the reboot, most card’s drivers on init, will invalidate the cache on the card to ensure dirty pages of data don’t get flushed to disk, to prevent scribbling junk data to the platters. From what I recall, this is true of both the megaraid and adaptec based cards.
> 
> Presumably, this cache invalidation is only on cards that don't have battery (or flash) backed write cache?     Doing that on a BB/FBWC system would negate the usefulness of said battery backed cache entirely.
> 


The ones with batteries will try to properly write the content of the cache to the disk right before the cache invalidate occurs. This is one of the few times when they aren’t lazy in their write patterns.

Regarding cheap vs. enterprise drives, agreed. You should absolutely never trust the disks to do the “right” thing with cheap models.

--
Gary L. Greene, Jr.
Sr. Systems Administrator
IT Operations
Minerva Networks, Inc.
Cell: +1 (650) 704-6633

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