[clug-talk] WD Green HDD's with ZFS

Gustin Johnson gustin at meganerd.ca
Sun Mar 25 21:37:29 PDT 2012


The feature that they removed is not that big of a problem if you are using
mdadm to create the array (which is what I do).

See here for more info on this:
http://en.wikipedia.org/wiki/Error_recovery_control

On Sun, Mar 25, 2012 at 10:26 PM, Andrew J. Kopciuch <akopciuch at bddf.ca>wrote:

> On March 25, 2012, Royce Souther wrote:
> > I have a few file servers that I am using Western Digiatl Green HDD's
> with
> > LVM. I am not using RAID1 because that would burn out a Green drive very
> > quickly. My servers are identical clones of each other and I like that
> > better then RAID1 because if a power supply dies the other server keeps
> the
> > work going until I can get the dead one fixed.
> >
>
> I'm not sure what you mean by "burn out".  It depends on the actual drives,
> but as I understand it, the draw back from using the WD drives is they do
> not
> have TLER.  That can cause stability (ie. performance degradation) if you
> have a nice RAID controller, as it will mark the drive(s) as unreliable
> because they are not responsive while fixing read/write errors themselves.
> That's only when you have read/write errors ... it's not all the time.
>
> > I one big issue with LVM is having to unmount the file system to resize
> the
> > partition. Every time I add a drive and grow the system it takes longer
> and
> > longer to go through the steps of fsck'ing the partiion and then resizing
> > it. It takes most of a day now to do this. ZFS does not have this
> problem.
> > As I understand it ZFS is able to resize the file system on the fly.
> > Mirrored Vdev would be like using RAID1 and that would kill a Green drive
> > but just using a ZFS to have the abilty to grow the FS on the file would
> be
> > good enough and should not hurt the Green drives. Does anyone know if
> using
> > ZFS not using mirror would be safe to use on drives like these?
>
> Your gripe is with your filesystem not LVM.
>
> You might not need to unmount the filesystem to resize it.  It depends on a
> lot of things.
>
> XFS & JFS filesystems _have_ to be mounted in order to resize actually.
> reiserfs can be either or.   For ext filesystems it depends on on the
> versions, kernel, and kernel options you have.  The utility you want is
> ext2online.
>
> You extend the underlying volume the filesystem is on with lvextend, and
> then
> extend the filesystem with ext2online.   e2fsadm apparently will do both of
> those steps in one shot for you.  There are some incompatibility issues
> between LVM1 & LVM2 utilities apparently
>
> I've never used ZFS, but it's apparently all-in-one.  Manage devices,
> volumes,
> partitions, FS ... all from the command line with the utilities.
>
> --
>
> If you have brand new servers (meaning not deployed).   I'd create your
> volumes, and use XFS on top of the volume.  You can "convert" the
> filesystem
> if already deployed, but that seems risky to me ... but should be possible.
>
>
> Andy
>
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