[gpfsug-discuss] Preliminary conclusion: single client, single thread, small files - native Scale vs NFS

Jan-Frode Myklebust janfrode at tanso.net
Wed Oct 17 14:50:38 BST 2018


Also beware there are 2 different linux NFS "async" settings. A client side
setting (mount -o async), which still cases sync on file close() -- and a
server (knfs) side setting (/etc/exports) that violates NFS protocol and
returns requests before data has hit stable storage.


  -jf

On Wed, Oct 17, 2018 at 9:41 AM Tomer Perry <TOMP at il.ibm.com> wrote:

> Hi,
>
> Without going into to much details, AFAIR, Ontap integrate NVRAM into the
> NFS write cache ( as it was developed as a NAS product).
> Ontap is using the STABLE bit which kind of tell the client "hey, I have
> no write cache at all, everything is written to stable storage - thus,
> don't bother with commits ( sync) commands - they are meaningless".
>
>
> Regards,
>
> Tomer Perry
> Scalable I/O Development (Spectrum Scale)
> email: tomp at il.ibm.com
> 1 Azrieli Center, Tel Aviv 67021, Israel
> Global Tel:    +1 720 3422758
> Israel Tel:      +972 3 9188625
> Mobile:         +972 52 2554625
>
>
>
>
> From:        "Keigo Matsubara" <MKEIGO at jp.ibm.com>
> To:        gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
> Date:        17/10/2018 16:35
> Subject:        Re: [gpfsug-discuss] Preliminary conclusion: single
> client, single thread, small files - native Scale vs NFS
> Sent by:        gpfsug-discuss-bounces at spectrumscale.org
> ------------------------------
>
>
>
> I also wonder how many products actually exploit NFS async mode to improve
> I/O performance by sacrificing the file system consistency risk:
>
> gpfsug-discuss-bounces at spectrumscale.org wrote on 2018/10/17 22:26:52:
> >               Using this option usually improves performance, but at
> > the cost that an unclean server restart (i.e. a crash) can cause
> > data to be lost or corrupted."
>
> For instance, NetApp, at the very least FAS 3220 running Data OnTap
> 8.1.2p4 7-mode which I tested with, would forcibly *promote* async mode to
> sync mode.
> Promoting means even if NFS client requests async mount mode, the NFS
> server ignores and allows only sync mount mode.
>
> Best Regards,
> ---
> Keigo Matsubara, Storage Solutions Client Technical Specialist, IBM Japan
> TEL: +81-50-3150-0595, T/L: 6205-0595
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