[Unionfs] disable unionfs cache?

[Pásztor Lénárd Zoltán]

...and it has the same result.

2007/7/16, Pásztor Lénárd Zoltán <lenard.pasztor at gmail.com>:
>
> OOPS.
> I missed the nfs layers set to nfs ro on this test session.
> So I repeat the test sorry...
>
> 2007/7/16, Pásztor Lénárd Zoltán <lenard.pasztor at gmail.com >:
> >
> >
> >
> >
> > > Lenard, what version of Unionfs have you been using?  I assume by
> > > "newest"
> > > you mean something in which we added the mtime-based cache-coherency
> > > support.  Are you?  All of our recent releases include that automatic
> > > cache-coherency support.
> >
> >
> > v2.0, 2.6.22.1-u1
> >
> > >
> > >
> > > One possibility is that you mount unionfs on top of nfs mounts, and
> > > the nfs
> > > mounts don't reflect server-side changes fast enough for you?  This
> > > would be
> > > an NFS issue, since it caches attributes from the server onto the
> > > client,
> > > and doesn't purge them frequently enough.  In that case, I'd recommend
> > > that
> > > you mount all of your NFS mounts with "-o noac" (No Attribute Cache),
> > > or
> > > play with the four options ac{reg,dir}{min,max}.
> > >
> > > In other words, if the lower file system doesn't see new objects' data
> > > and
> > > attributes (esp. mtime/ctime), then Unionfs, sitting above, cannot see
> > > them
> > > either -- thus you have to first make the lower file systems see the
> > > updated
> > > file attributes.
> >
> >
> > My test config:
> > 2 nfs servers loadbalanced via LVS. Backend filesystem is ocfs2 on top
> > of a drbd 0.8. block device (primary/primary config)
> > This is for HA.
> >
> > Clients have an initrd. Initrd mounts the root filesystem.
> > NFS related kernel command line opions:
> > nfsroot=10.0.3.2:/storage,soft,noac
> >
> > #nfs root mounted by kernel internally at boot time (autoconfig):
> > nfs:/storage /root nfs
> > ro,sync,vers=3,rsize=8192,wsize=8192,acregmin=0,acregmax=0,acdirmin=0,acdirmax=0,soft,noac,nolock,proto=tcp,timeo=7,retrans=3,sec=sys,addr=10.0.3.20 0
> >
> > # local storage for write support
> > /dev/disk/by-label/local /union_local ext3 rw,data=ordered 0 0
> >
> > # 'new' root filesystem by unionfs (mounted by initrd)
> > unionfs / unionfs
> > rw,dirs=/union_local=rw:/root/layers/by-host/app1=ro:/root/layers/by-role/app=ro:/root/systems/current=ro
> > 0 0
> >
> > There is only one nfs export ( /storage ), but the union branches has 3
> > nfs layer. This layers are in the same nfs mount's sub directories.
> >
> > The nfs export (/storage) hierarchy:
> > /layers
> > /layers/by-host/app1
> > /layers/by-host/app1/etc
> > /layers/by-host/app1/etc/hostname "app1"
> > /layers/by-role/app
> > /layers/by-role/app/etc
> > /layers/by-role/app/etc/hostname "app"
> > /systems
> > /systems/current/
> > /systems/current/bin
> > /systems/current/boot
> > /systems/current/dev
> > ...
> > /systems/current/etc/hostname "base-system"
> > ...
> >
> > For testing all layer has the /etc/hostname file.
> > The local storage is empty ext3 filesystem.
> > So, when the client boots it sets the hostname from by-host branch to
> > "app1".
> >
> > (nfs)$cat /storage/layers/by-host/app1/etc/hostname
> > app1
> >
> > (client)$cat /etc/hostname
> > app1
> > # from /storage/layers/by-host/app1/etc/hostname. It's ok.
> >
> >
> > (nfs)$echo "xyz" > /storage/layers/by-host/app1/etc/hostname
> > (nfs)$cat /storage/layers/by-host/app1/etc/hostname
> > xyz
> >
> > (client)$cat /etc/hostname
> > app1
> > # It not changed on client side. :(
> >
> > (server)$rm /storage/layers/by-host/app1/etc/hostname
> > # source deleted from by-host branch
> >
> > (client)$cat /etc/hostname
> > app
> > # from /storage/layers/by-role/app/etc/hostname. It's ok.
> >
> > (nfs)$echo "xyz" > /storage/layers/by-host/app1/etc/hostname
> > # the /storage/layers/by-host/app1/etc/hostname now exists
> >
> > (client)$cat /etc/hostname
> > app
> > # client site not changed :(
> >
> > (server)$rm /storage/layers/by-role/app/etc/hostname
> >
> > (client)$cat /etc/hostname
> > xyz
> > # from /storage/layers/by-host/app1/etc/hostname. It's ok.
> >
> >
> >
> > --
> > thx,
> >
> > Lénárd
>
>
>
>
> --
> üdv,
>
> Lénárd




-- 
üdv,

Lénárd
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