[CentOS] Are SSD disks worth the cost for server usage?

[Brian Mathis]

On Tue, Jan 12, 2010 at 7:30 AM, Mathieu Baudier <mbaudier at argeo.org> wrote:
> Hi,
>
> we want to upgrade our infrastructure and are considering renting two
> different types of server by a provider:
>
> - A: one is with 80 GB SSD (and 12 GB memory)
> http://www.ovh.co.uk/products/eg_ssd.xml
> - B: the other with 750 GB SATA2 (and 8 GB memory).
> http://www.ovh.co.uk/products/eg_best_of.xml
>
> The target infrastructure will host:
> - a few public web sites (PHP / MySQL)
> - a development infrastructure (subversion, bugzilla, automated builds)
>
> This will use KVM virtualization with Cent OS 5.4 hosts and guests.
>
> On the long run we will probably rent quite a few of type B depending
> on our needs of space and computing power.
>
> My question is whether it is worth using one of type A (with SSD
> drives) in order to host the critical data such as the web sites and
> the subversion repository (critical in the sense that these services
> should be fast, always available, and the related data as safe as
> possible).
>
> This critical server will be more read oriented than write.
> We will probably use a hardware RAID 1 with battery backed unit on it.
>
> My understanding is that SSD are much much faster.
> Is it really true in the real world?
>
> Are SSD drives also safer?
> (that is, less likely to crash under load)
> Or to the contrary?
>
> I have read/heard conflicting opinions so far and I'll be happy to
> hear opinions/experiences on SSD drives in a server settings from
> people on the list.
> More general comments about our plans are always welcome of course!
>
> Cheers,
>
> Mathieu
>
> PS: we will actually rent them in France, but I put links to the
> equivalent in Britain in order to have the description in English.
> For reference and for the French-speaking people, here are the actual
> servers we consider:
> http://www.ovh.com/fr/produits/eg_ssd.xml
> http://www.ovh.com/fr/produits/eg_best_of.xml
> (they are exactly the same)


It's too early to start putting Flash-based SSDs in servers unless you
have a really specific need.  Based on you description above, this
does not sound like a hugely high-performance I/O server.  I suggest
you look into 15k RPM disk drives setup in a RAID10 configuration.
That will get you the most speed.  Additionally, the Linux IO system
uses RAM extensively for caching, so you'll be getting the benefit of
that anyway.