Re: [gpfsug-discuss] SMB share size on disk Windows

Wed, 22 May 2019 21:01:20 -0700

The parameter 'allocation roundup size' was introduced in Samba back
in 2005. Since then the world has moved on to SMB2 and SMB3. It is not
clear whether this has any performance benefits these days. Also with
Samba in Scale, the only effect is that the reported allocation size
is rounded up, but the space is not actually allocated.
 
|Allocation roundup size actually was a performance win back
|in the day (SMB1). Reporting it as larger (1MB) caused the
|SMB1 client to issue larger read requests against Samba than
|it did against a Windows server which reported the NTFS
|allocation extent.
|
|In the world of SMB2, not sure how much it's needed anymore.
 
You can change this parameter for a test to get consistent reporting
of used space:
 
/usr/lpp/mmfs/bin/net conf setparm global 'allocation roundup size' 0
 
In case there is a problem, remove it again to revert back to the
default:
 
/usr/lpp/mmfs/bin/net conf delparm global 'allocation roundup size'
 
Regards,
 
Christof Schmitt || IBM || Spectrum Scale Development || Tucson, AZ
[email protected]  ||  +1-520-799-2469    (T/L: 321-2469)
 
 
----- Original message -----
From: "L.walid (PowerM)" <[email protected]>
Sent by: [email protected]
To: "[email protected]" <[email protected]>
Cc:
Subject: [EXTERNAL] Re: [gpfsug-discuss] SMB share size on disk Windows
Date: Wed, May 22, 2019 6:01 PM
 
Hi Everyone,
 
Through some research, i found it's a normal behavior related to Samba "allocation roundup size" , since CES SMB is based on Samba that explains the behavior. (Windows assumes that the default size for a block is 1M).
As such, i found somewhere else that changing this parameter can decrease performance, so if possible to advise on this. For the block size on the filesystem i would still go with 256k since it's the recommended for File Serving use cases.
 
Thank you
 
References : 
 
On Wed, May 22, 2019 at 11:59 PM L.walid (PowerM) <[email protected]> wrote:
Hi,
 
We are contacting you regarding a behavior observed for our customer gpfs smb shares. When we try to view the file/folder properties, the values reported are significantly different from the folder/size and the folder/file size on disk.
 
We tried to reproduce with creating a simple text file of 1ko and when we check the properties of the file it was a 1Mo on disk! 
 
I tried changing the block size of the fs from 4M to 256k , but still the same results 
 
Thank you 
--
Best regards, 
 
Walid Largou
Senior IT Specialist
Power Maroc
Mobile : +212 621 31 98 71
320 Bd Zertouni 6th Floor, Casablanca, Morocco


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--
Best regards, 
 
Walid Largou
Senior IT Specialist
Power Maroc
Mobile : +212 621 31 98 71
320 Bd Zertouni 6th Floor, Casablanca, Morocco


This message is confidential .Its contents do not constitute a commitment by Power Maroc S.A.R.L except where provided for in a written agreement between you and Power Maroc S.A.R.L. Any authorized disclosure, use or dissemination, either whole or partial, is prohibited. If you are not the intended recipient of the message, please notify the sender immediately.
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