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The Smart Response Technology (SRT) of a Intel Z68 can operate in two modes: Enhanced (Write-through) or Maximized (Write-back). Clearly, the Maximized mode sounds better since it will give you near SSD speed even with a relative small SSD.

The manual (Last two links on this page ) says the following about Maximized mode:

In this mode, cached data is written to the accelerated disk or volume at intervals to increase performance. If the cache device is reported as missing or failed and it contained data that had not yet been written to the accelerated disk or volume, then that data will be lost.

To me, this sounds like only when there is "dirty" data on the SSD cache and the SSD fails, data will be lost. A power outage will not cause any trouble since it will write them to the HDDs when the power is back.

However, a test by PC Perspective notes the following:

..I'd personally stick with enhanced mode unless I was extremely confident in the stability of my system (and had it connected to a good UPS).

So, does this mean SRT requires a uninterruptible power supply to prevent data loss?

Update #1

I have now talked to Intel support (using web chat) and this is the outcome:

Me: .... If I have an accelerated system using SRT and there is a power outage, will the ICH/Z68 write the outstanding data (that is still only on the SDD and not on the HD) write the outstanding blocks onto the HDD when the power returns? ...

Victor: Every device that will work as cache will loose the information on a power failure. In your case the data in the cache ( Solid-State Drive ) will be lost.

Me: ... Does this also mean I get a cache problem if Windows just crashes (but the power remains)? Would this also invalid all data inside the cache?

Victor: Correct, but the amount of data should not be that much, it will depend in the process that you are doing and the speed of your hard drives.

Me: Can you please give me a link or something where this is documented? ...

Victor: Unfortunately this information is not posted on the web site, but I will send your request up so that they add it. ....

Update #2

I also talked to the technical writer of the last Z68 test in the last c't - he is disagreeing with what the Intel Support said so they will now try to simply test it out. If I have new information, I will update again.

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I really hopped that somebody could dig up some information about this, but so far it really seems that no exact information exist about this issue. Basically @harrymc and CodeBlend are saying the same, so it's impossible for me to choose the "best" answer. I will award this bounty and the answer to CodeBlend since he was first (sorry harrymc). –  TeX HeX Aug 9 '11 at 17:06
    
In theory, if your system "froze", in Maximized mode, Intel's drivers should still be able to recover the data, since it's on the SSD still. However, if your SSD were to say, instantly fail, you'd lose all the pending write-thru data, forever. Does that make sense? That's why I still run maximized mode, and use Crashplan/etc. for realtime backups of my important files. –  Nicholas Jun 15 '13 at 13:42

3 Answers 3

up vote 1 down vote accepted
+50

Seem to be a recomendation as opposed to a necessity but you may find issues arise without. From reading the discussion pointsin the comments in the discussion here:

And yes, a UPS is recommended as having a power outage while it's syncing a few MB of data would be pretty bad. For those folks, the Enhanced mode is probably recommended.

http://www.maximumpc.com/article/features/everything_you_need_know_about_intels_new_z68_chipset?page=0,1

I think the test by PC Perspective's notes say it well. In my experience typically it's servers that have a UPS, not that a single home/client PC couldn't have one especially without a server to backup to but again it just depends how far you want to go / budget / how valuable the data is.

To directly answer your question:

In enhanced mode no but in Maximized mode, to be absolutely sure, yes is the answer

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Thanks for the answer, but this would assume that the controller only tries once to sync the data from the SSD to the HD (at least that's what I interpret from the quote). To be honest, I can't believe this is true because what would happen if the HDD has one or more bad blocks? There must be some sort of retry procedures build-in or else any (correctable) HD error could cause the entire system to crash. –  TeX HeX Aug 4 '11 at 16:39
    
Neither me or @harrymc are experts it seems so we don't have the first hand knowledge, I suppose it is up to you based on articles and research as to how best to configure your setup. –  CodeBlend Aug 5 '11 at 8:36
    
@TeX HeX: All hard disks contain redundant sectors to replace defective ones. I agree that the complexity of this SSD/HDD hybrid approach probably causes this technology to be less robust. –  harrymc Aug 6 '11 at 6:57

Since yesterday I can answer this question myself: No, no data is lost.

While moving about 100 GB (10k+ files) from one partition to another (both on the accelerated array), the main power in my house went down. The file move was about 60% done at this time.

Upon restoring power and turning the computer back on, the Intel controller displayed the following during POST: POST image

Some lines are missing, but to me this looks like it has detected it has dirty data on the SSD and fixed it.

Checking the files on the new and the old location from my backup I could verify that no file was lost or damaged.

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This was done with Maximized mode? –  Nicholas Jun 15 '13 at 13:40

I don't have first-hand knowledge, but Intel Smart Response Technology Explained says :

The two different modes set up the SSD caching in different ways.

Enhanced mode is designed for maximum security, reducing the possibility of data loss but also limiting write speed as it writes data to the SSD and HDD at the same time.

Maximized mode is designed for optimum performance, writing data to the SSD and only periodically transferring it to the hard drive. This means that if anything should go wrong with the SSD, you could lose some data.

The outcome of an SSD failure would depend largely on what the SSD was caching at the time of failure, so it’s difficult to predict how it would affect your system.

It sounds like a power failure could lose the data from the hard-disk, but maybe not from the SSD (the emphasis is on "maybe").

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Thanks for the answer, so this basically means that no UPS would be needed. Because the data would still be on the SSD and upon the next start, it would be written to the HD? –  TeX HeX Aug 4 '11 at 16:35
    
I don't think so, since every reviewer of this technology that I have seen warns against using Maximized mode when a crash is possible. I would guess that the SSD only serves as a "window" upon the HDD, so once the HDD is corrupted then the SSD is also corrupted. If I were you, I would not dare use this mode at all, UPS or not (since Windows itself is also is entirely capable of crashing totally). –  harrymc Aug 4 '11 at 17:02
    
So the advise is to stop using a SRT with Windows and using Linux with a UPS? :-). Just kidding, I think I'm getting your point. –  TeX HeX Aug 4 '11 at 17:14
    
It shouldn't matter much to SRT whether one uses Windows or Linux. –  harrymc Aug 4 '11 at 20:18
    
A German PC magazine (c't) tested Z68 mainboard two weeks ago and they wrote that Linux does currently not support SRT. A SRT enabled configuration will appear as normal Drive/Raid in Linux. –  TeX HeX Aug 4 '11 at 20:40

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