[gpfsug-discuss] RAID type for system pool

[Ed Wahl]

That isn't necessarily true.  The ONLY way to ensure you aren't saving 
tiny little <~400 byte files is to have encryption enabled with the 
advanced license.   There are QUITE a few types of MD that can be saved, 
just look at the output from a file using mmlsattr -L...

Ed


On 09/11/2018 11:48 AM, Buterbaugh, Kevin L wrote:
> Hi Marc,
>
> Understood … I’m just trying to understand why some I/O’s are flagged 
> as metadata, while others are flagged as inode?!?  Since this 
> filesystem uses 512 byte inodes, there is no data content from any 
> files involved (for a metadata only disk), correct?  Thanks…
>
> Kevin
>
>> On Sep 11, 2018, at 9:12 AM, Marc A Kaplan <makaplan at us.ibm.com 
>> <mailto:makaplan at us.ibm.com>> wrote:
>>
>> Metadata is anything besides the data contents of your files.
>> Inodes, directories, indirect blocks, allocation maps, log data ... 
>>  are the biggies.
>>
>> Apparently, --iohist may sometimes distinguish some metadata as 
>> "inode", "logData", ...  that doesn't mean those aren't metadata also.
>>
>>
>>
>>
>> From: "Buterbaugh, Kevin L" <Kevin.Buterbaugh at Vanderbilt.Edu 
>> <mailto:Kevin.Buterbaugh at Vanderbilt.Edu>>
>> To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org 
>> <mailto:gpfsug-discuss at spectrumscale.org>>
>> Date: 09/10/2018 03:12 PM
>> Subject: [gpfsug-discuss]  RAID type for system pool
>> Sent by: gpfsug-discuss-bounces at spectrumscale.org 
>> <mailto:gpfsug-discuss-bounces at spectrumscale.org>
>> ------------------------------------------------------------------------
>>
>>
>>
>>
>> *From: * _gpfsug-discuss-owner at spectrumscale.org_ 
>> <mailto:gpfsug-discuss-owner at spectrumscale.org>
>> *Subject: Re: [gpfsug-discuss] RAID type for system pool*
>> *Date: * September 10, 2018 at 11:35:05 AM CDT
>> *To: * _klb at accre.vanderbilt.edu_ <mailto:klb at accre.vanderbilt.edu>
>>
>> Hi All,
>>
>> So while I’m waiting for the purchase of new hardware to go thru, I’m 
>> trying to gather more data about the current workload.  One of the 
>> things I’m trying to do is get a handle on the ratio of reads versus 
>> writes for my metadata.
>>
>> I’m using “mmdiag —iohist” … in this case “dm-12” is one of my 
>> metadataOnly disks and I’m running this on the primary NSD server for 
>> that NSD.  I’m seeing output like:
>>
>> 11:22:13.931117  W       inode    4:299844163      1    0.448  srv   
>> dm-12 <redacted>
>> 11:22:13.932344  R    metadata    4:36659676       4    0.307  srv   
>> dm-12 <redacted>
>> 11:22:13.932005  W     logData    4:49676176       1    0.726  srv   
>> dm-12 <redacted>
>>
>> And I’m confused as to the difference between “inode” and “metadata” 
>> (I at least _think_ I understand “logData”)?!?  The man page for 
>> mmdiag doesn’t help and I’ve not found anything useful yet in my 
>> Googling.
>>
>> This is on a filesystem that currently uses 512 byte inodes, if that 
>> matters.  Thanks…
>>
>> Kevin
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