10 Oct
2011
10 Oct
'11
3:43 p.m.
Hi Phil,
On Fri, Oct 07, 2011 at 08:29:23AM +0100, Phil Stewart wrote:
On 06/10/2011 20:32, Andy Smith wrote:
Do they typically mention this in the specs? I am concerned because
the afewmoreamps.com link I posted above was using the relatively
new OCZ Vertex 3 and were still seeing this issue.
If they say "Enhanced power-loss data protection" in the specs, is
this what we're talking about? That's on Intel spec sheets; I don't
know what the equivalent might be for e.g. OCZ.
Given that they can lose transactions on Vertex 3 I think that we
can assume that no Vertex 2 or 3 SSD has this power loss
protection.
SSDs can lose transactions if they are abruptly
powered off, even if
you disable their write cache:
http://www.evanjones.ca/intel-ssd-durability.html
http://www.afewmoreamps.com/2011/08/fsync-durability.html
One of the differences (particularly on newer models) between consumer
and enterprise SSDs is enterprise models tend to come with a big power
cap to ensure pending writes can be completed in the event of power loss.
Some of the older gen drives don't have this (in particular the Intel
X25-E and the now rather vintage X25-M). You may want to take a look at
the Intel 710 (or maybe the 320, which isn't quite so hideously
expensive). Other manufacturers also have designs with power loss
protection, so it's certainly worth shopping around. Enterprise SSDs do tend to be eye-wateringly expensive
though: I guess
the balance is between how much it costs for full blown enterprise SSDs
vs sticking some cheap Vertex 2s or somesuch behind a hardware raid card.
How do you work out which products are "enterprise"?
http://www.span.com/index.php?cPath=73_499_1452&page=1&sort=221d
The above URL shows some Intel X25-Ms as being more expensive than
Intel 320s of the same capacity.
Here's a comparison of some products in the price range I'm
considering:
http://www.span.com/compare.php?image1=submitname&&compare[]=34034&…
or http://is.gd/vnKuiY
Hovering over the product image will give a tooltip with the actual
product name. Of these, Span thinks only the Intel 510 is
"enterprise". It doesn't list "Enhanced power-loss data
protection"
on its actual spec sheet though, whereas the Intel 320 does.
The cheapest Intel 710 that Span do seems to be £4.72/GB:
http://www.span.com/product_info.php?products_id=35173
That is about 3 times what I was hoping to spend, indeed. Just
buying more servers/spindles probably becomes cheaper, at that
point.
Cheers,
Andy
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