CentOS - Jan 2010 - Are SSD disks worth the cost for server usage?

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)

> 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
<snip>
> 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).
The real question is how many hits/hour you expect. I interviewed last
year at a major advertiser... but (and I'm trying to remember from last
May) they were getting hundreds of millions of hits per day.

For tens or hundreds of thousands, the normal drives are more than fine.
That, of course, also depends on the sites: in early '03, I looked at a
small site, and the guy's web pages took *forever* to load... but that was
because he'd taken photos of his work, and each page had something like
four or six photos, each of which was 1.5M-4M.
<snip>
> 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?
The enterprise grade ones. And, if they're not enterprise grade, and the
provider's cheaping out and using the kind sold in stores, they're not
as
reliable. If this is that important, I trust you're looking at SLA in the
contract.

        mark

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.

Mathieu Baudier wrote:
> 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).
Go with 10/15k RPM SAS, not Intel SSD or SATA if you want best
availability. Intel SSDs have had firmware issues since they came
out, I doubt we've seen the end of firmware changes on them.

If you want even higher availability go with a better provider,
this is a good cloud hosting provider which uses VMware and high
availability storage -

http://www.terremark.com/technology-platform/nap-data-centers.aspx

http://vcloudexpress.terremark.com/

Looks like they have 4 locations in Europe, I haven't used them
myself but went through a presentation for them last year very
impressive, though they are pricey. If you have simple requirements
it's probably not bad though(will be a few times more $ than the
hosting provider your looking at, but hey you wanted fast, always
available, and safe, those aren't cheap). You can provision machines
yourself, manage a remote firewall, and load balancers from their
web UI.

nate

Hi,
> - 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 Intel SSD are fast but have a history of firmware problems. So I
wouldn't suggest using them on a mission critical data. Personally I
think asking for more RAM on the SATA server would do more for
performance especially since you are going to be running several VM.

Just my noobish 2 cents' worth.