Re: journal on an ssd

Look at: http://www.fusionio.com/Products.aspx

At 120K IOPS @1K blocks, it should make for a very good journaling device.

It's not an SSD per se; it bypasses old disk controllers altogether (very innovative block device design).

The block device layer and hardware are tailored for NAND failure idiosyncrasies... which results in their data loss is less than any available SSD or rotating disk.

Put two together in a RAID1 configuration to compensate for device failures (assure you have 2 PCIe x8 slots available).

Chris

On Wed, Sep 10, 2008 at 10:05 AM, Tobias Oetiker <tobi oetiker ch> wrote:

Hi Eric,

I have not tested this, but since we are putting about 16 different
journals on this one ssd, I would assume that the loss through
seeking between the journals would be pretty bad, and again bring
back that inter-filesystem-dependency we were trying to loose with
this measure.

cheers
tobi

Today Eric Sandeen wrote:

> Tobias Oetiker wrote:
> > Experts,
> >
> > What happens if the disk hosting an external journal of a filesytem
> > running with data="" goes bust.
> >
> > The Backstory ...
> >
> > I have been batteling with filesystem performance for some time
> > now. Our setup is a HW Raid(6) with LVM on top and ext3 filesytems.
> >
> > Recently we added an SSD to our setup and have moved all the journals
> > to this ssd. This has dramatically improved performance and
> > especially reduced the interdependence between performance of
> > different partitions hosted on the same RAID.
> >
> > http://insights.oetiker.ch/linux/external-journal-on-ssd.html
>
> How does this compare to putting journals on a separate non-ssd device?
>
> -Eric
>
>

--
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi oetiker ch ++41 62 775 9902 / sb: -9900

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