Re: Is filesystemio_options relevant when the database is on ASM ?

Hi Hemant,

1) Answer to your original question is - NO, in my experience I have not observed the setting of filesystemio_options to be relevant on ASM, if there is no other layer such as NFS underneath ASM. Frits has already alluded to this. The last time I did a test of this was on 10gR2 many moons ago, when I observed identical system calls by trussing and dtracing DBWR and foreground processes (without NFS).

2) There is an associated note - Physical Corrupted Blocks consisting of all Zeroes indicate a problem with OS, HW or Storage (Doc ID 1545366.1), which may be of interest to you (if you have not already seen it). Basically, the note states that corrupted "zeroed out" blocks definitely => an issue in the underlying OS/storage layer.

3) The reason why I mention the above is that, I have set filesystemio_options to SETALL in the past 12+ years till date (even on ext4) and have yet to encounter the issue mentioned in Doc ID - 1487957.1. I hope I have not jinxed the good run ;) It is quite possible that I have been lucky ALL this time to not encounter the error, but I think I am leaning on the side of Doc ID - 1545366.1, which clearly indicates that I have worked with some good Sys & Storage Admins, who got their part done right :)

Having said the above, it is also comforting to note from Doc ID - 1487957.1 that the following Linux releases fixes this "OS/storage layer issue" on ext4:

1) Oracle Linux version - kernel-uek-2.6.39-200.29.3.el6uek

2) RHEL5 - kernel-2.6.18-238.el5 - RHEL5.6 Errata RHSA-2011-0017 or later
3) RHEL6 - kernel-2.6.32-71 or later  

Cheers,

Gaja

Gaja Krishna Vaidyanatha,

CEO & Founder, DBPerfMan LLC
http://www.dbperfman.com
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________________________________
 From: "Chitale, Hemant K" <Hemant-K.Chitale_at_sc.com>
To: Mark W. Farnham <mwf_at_rsiz.com> 
Cc: ORACLE-L <oracle-l_at_freelists.org> 
Sent: Thursday, October 16, 2014 7:19 PM
Subject: RE: Is filesystemio_options relevant when the database is on ASM ?
 


Is filesystemio_options relevant when the database is on ASM ?
Found Support Note “ORA-1578 ORA-353 ORA-19599 Corrupt blocks with zeros when filesystemio_options=SETALL on ext4 file system using Linux (Doc ID 1487957.1)”
 
Hemant K Chitale
 
 
From:Mark W. Farnham [mailto:mwf_at_rsiz.com] 
Sent: Thursday, October 16, 2014 11:04 PM
To: frits.hoogland_at_gmail.com; Chitale, Hemant K
Cc: 'ORACLE-L'
Subject: RE: Is filesystemio_options relevant when the database is on ASM ?
 
The immediate side question becomes: Can we catalog any situations in which the ‘setall’ setting is suboptimal?
 
IF there are no known situations where ‘setall’ is harmful, then I believe it would be wise to set it as standard operating procedure.
IF there are some known situations where ‘setall’ is suboptimal, then the catalog of exceptions would be gold.
(Setting it when it does no harm operationally being irrelevant beyond a few microseconds at database restart to parse the parameter.)
 
mwf
 
From:oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce@freelists.org] On Behalf Of Frits Hoogland
Sent: Thursday, October 16, 2014 5:35 AM
To: Hemant-K.Chitale_at_sc.com
Cc: ORACLE-L
Subject: Re: Is filesystemio_options relevant when the database is on ASM ?
 
Hi Hermant,
 
With version 11 ASM (ASM needs to be available on the node where the database lives), and when using Exadata, filesystemio_options is NOT relevant to the database processes when using files (redo, data, temp) on local ASM managed devices. 
I am not sure with version 12, probably the locality between the device and the ASM instance which it manages is relevant.
 
When using NFS underneath ASM, I've witnessed filesystemio_options being honoured by the database, which means it needs setting it to 'setall' for the combination AIO+DIO. Which makes sense, because you need to create a file on a (NFS) filesystem to be used as ASM disk device.
 
Frits Hoogland

http://fritshoogland.wordpress.com
frits.hoogland_at_gmail.com
Office : +31 20 5939953
Mobile: +31 6 14180860
 
On 16 Oct 2014, at 11:25, Chitale, Hemant K <Hemant-K.Chitale_at_sc.com> wrote:
 
Is filesystemio_options relevant when the database is on ASM ?
 
Hemant K Chitale
 
 

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