Ayaz Anjum and others,
I think once you move into NFS over TCP in a client
server env, the chance for lost data is significantly
higher than just a disconnecting a cable,
Scenario, before a client generates a delayed write
from his violatile DRAM client cache, client reboots,
and/or a asynchronous or a delayed write is done,
no error on the write and the error is missed on the
close because the programmer didn't perform a fsync
on the fd before the close and/or expect that a
close might fail,
and/or the tcp connection is lost and the data is
not transfered,
Thus, I know of very few FSs that can guarantee against
data loss. What most modern FSs try to prevent is data
corruption and FS corruption,...
However, I am surprised that you seem to indicate that
no hardware indication is/was present to indicate some
form of hardware degredation/failure had occured.
Mitchell Erblich
----------------
is generated because of
the delayed
On 11-Mar-07, at 11:12 PM, Ayaz Anjum wrote:
>
> HI !
>
> Well as per my actual post, i created a zfs file as part of Sun
> cluster HAStoragePlus, and then disconned the FC cable, since there
> was no active IO hence the failure of disk was not detected, then i
> touched a file in the zfs filesystem, and it went fine, only after
> that when i did sync then the node panicked and zfs filesystem is
> failed over to other node. On the othernode the file i touched is
> not there in the same zfs file system hence i am saying that data
> is lost. I am planning to deploy zfs in a production NFS
> environment with above 2TB of Data where users are constantly
> updating file. Hence my concerns about data integrity.
I believe Robert and Darren have offered sufficient explanations: You
cannot be assured of committed data unless you've sync'd it. You are
only risking data loss if your users and/or applications assume data
is committed without seeing a completed sync, which would be a design
error. This applies to any filesystem.
--Toby
> Please explain.
>
> thaks
>
> Ayaz Anjum
>
>
>
> Darren Dunham <[EMAIL PROTECTED]>
> Sent by: [EMAIL PROTECTED]
> 03/12/2007 05:45 AM
>
> To
> zfs-discuss@opensolaris.org
> cc
> Subject
> Re: Re[2]: [zfs-discuss] writes lost with zfs !
>
>
>
>
>
> > I have some concerns here, from my experience in the past,
> touching a
> > file ( doing some IO ) will cause the ufs filesystem to failover,
> unlike
> > zfs where it did not ! Why the behaviour of zfs different than ufs ?
>
> UFS always does synchronous metadata updates. So a 'touch' that
> creates
> a file is going to require a metadata write.
>
> ZFS writes may not necessarily hit the disk until a transaction group
> flush.
>
> > is not this compromising data integrity ?
>
> It should not. Is there a scenario that you are worried about?
>
> --
> Darren Dunham
> [EMAIL PROTECTED]
> Senior Technical Consultant TAOS http://
> www.taos.com/
> Got some Dr Pepper? San Francisco, CA bay
> area
> < This line left intentionally blank to confuse you. >
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