SSD Experience

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Re: SSD Experience (on developer machine)

Isaias alves
>> we are probably running out of topic here, but for the record, there is
>> also someone lamenting about ssd

> I find all of this highly on-topic. SSD reliability is an important
> issue. We use customer-grade SSDs (Intel 510 were the latest ones
> bought) in our servers as we see no point in enterprise-grade
> reliability when we are mirroring machines.

Yes, it is on-topic. Tks for all informations.


>> so, as far as developer machines are involved, you should go for OSes
>> that use the disk efficiently [...]

> Efficiently as speed, yes. Efficiently as minimizing writes, no. On the
> contrary, disk swapping is much faster on SSDs along with temporary
> files and all the other secondary writes that are done throughout the
> day. Hit them hard. They're designed for it.


Good... the speed is not a most important parameter always. The merge of SSD
and NON-SSD ( backup? low relevance/old records? etc.. ). for me, is a
example of complete solution ( fast and secure ) using lucene.

--
I$@I@$
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Re: SSD Experience (on developer machine)

Toke Eskildsen
In reply to this post by Federico Fissore
On Wed, 2011-08-24 at 13:42 +0200, Federico Fissore wrote:
> I add a question. Toke you said that "the current state of wear can be
> queried". How?

With a S.M.A.R.T.-tool, preferably up-to-date to get it to display the
vendor-specific properties in an easy to understand manner.

On my Ubuntu-box with a 160GB Intel X25-M G2,
sudo smartctl -A /dev/sdb1
gives me (abbreviated by me)
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE
UPDATED  WHEN_FAILED RAW_VALUE
  9 Power_On_Hours          [...]   9372
 12 Power_Cycle_Count       [...]     50
225 Host_Writes_Count       [...] 176888
233 Media_Wearout_Indicator [...]      0
and
http://forums.storagereview.com/index.php/topic/28649-intel-x25-interpreting-smart-values/
tells me that I'll have to divide the raw value from #225 with 29,8,
resulting in 5,8TB written in total (about 15GB/day).

Some vendors provide specific software that makes it much easier.
Intel makes the Intels SSD Toolbox that unfortunately is Windows only.

> AFAIK, cells target for a write are chosen just randomly between the
> free ones, ignoring other factors

That would be a very bad wear-leveling strategy. Keeping a counter for
each cell and selecting the free cell with the lowest count is trivial.
However, given the bumpy road to great SSDs, I am sure that some vendors
has done it this way.

Regards,
Toke Eskildsen


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Re: SSD Experience (on developer machine)

Toke Eskildsen
In reply to this post by David Nemeskey
On Wed, 2011-08-24 at 11:46 +0200, David Nemeskey wrote:
> Theoretically, in the case described above, it would be possible to move
> 'static' data (data of cells that have not been written to for a long time) to
> the 5GB in question and use the 'fresher' cells as free space; this could be
> done in a round-robin fashion.

A fine idea. Of course it is not guaranteed that data remains static,
but the probability if high.

> Do SSDs (or some one them) implement a similar
> functionality? Or alternatively, are there tools that do this?

I am sorry, but I have no idea if this is the case.


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