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Will I lose any benefits of an SSD drive if I JBOD it with a SATA HDD?

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June 16, 2012 5:15:39 PM

I am looking to get a SSD drive for the performance benefits but would like to supplement it with a SATA HDD for more storage space. I prefer to have one logical disk as opposed to a separate C and D drive.

If I JBOD the two drives together will I miss out on the benefits of the SSD or will it simply write everything to the SSD and then move on to the SATA HDD?

I will be setting up the JBOD from the on-board RAID controller.

So far I have not yet been able find a definite answer.
a c 326 G Storage
June 16, 2012 7:26:54 PM

You will lose TRIM for now, and I strongly suspect that your performance will decline considerably, as the array performance is dictated by the slowest device.
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June 16, 2012 7:35:54 PM

RealBeast said:
You will lose TRIM for now, and I strongly suspect that your performance will decline considerably, as the array performance is dictated by the slowest device.

That is absolutely correct, you will lose any performance gains that the ssd would have on it's own, if you want a larger OS drive you're gonna have to either get a larger SSD or use a RAID array that uses 2 or more ssd's (of the same performance grade preferably the same model). Although then you're gonna have to manually do TRIM functions since TRIM is disabled with any RAID array.

Another option is to use a small SSD as a cache drive on a capable motherboard, but that isn't as effective as a dedicated SSD OS drive.
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June 16, 2012 10:00:36 PM

RealBeast said:
Thorkle, have you tested the RST 11.5 beta that supports TRIM in R0? My test machines are busy but my brother claims it works. http://www.station-drivers.com/telechargement/intel/sat...(www.station-drivers.com).exe

Hopefully, the final release will be coming soon.

Oh wow, that is awesome news! I have been waiting forever for this. I can't wait until they have solid drivers for it. Then I can get a second vertex 3 and be flying! :pt1cable:  I would test it out, but I only have 1 ssd and it is in my main machine, so I will just wait until there are verified stable drivers, but this gives me high hopes.
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June 19, 2012 1:05:00 AM

RealBeast said:
You will lose TRIM for now, and I strongly suspect that your performance will decline considerably, as the array performance is dictated by the slowest device.


Why will my performance decline ? With JBOD, will it not write all data to the SSD at its native speed and then move over to the SATA HDD? Does setting up JBOD create an array?
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a c 326 G Storage
June 19, 2012 1:44:18 AM

Well since all the physical drives are just mapped to one logical drive the data will get written to whatever location, and AFAIK Windows does not provide a way to allocate the specific destination block by physical drive to which it will go -- only to the logical drive when there are multiple physical drives in the logical drive. JBOD is really not an array in the sense of RAID, but rather just a concatenation of all of the physical drives into one logical drive. In other words without SRT the SSD will not perform caching for the HDD but would just be the first or last bunch of blocks where data is written.

How are you implementing the JBOD, through spanning into a volume set in Windows or with motherboard/add in card RAID? Although JBOD is not RAID many controllers allow it as an option, which is where I have concern that the SSD may lose TRIM support, that the controller would not pass the TRIM command until RST 11.5, although I am not sure that if that is an issue that 11.5 will address it, as it is directed at RAID 0. If you are implementing through Windows you may still have TRIM capability as there is no controller in the way, which seems to be the issue currently.

Another negative is that you will lose unknown data if a drive fails, maybe nothing significant, but it really depends what ends up on that drive.

While I do not recommend it, and I would prefer using the SSD alone for best performance, a more controlled approach would be to use Intel SRT for caching. Then at least you know you will get a performance improvement for the HDD.

The real useful purpose for JBOD for home users is to allow drives of different sizes to be combined into a larger volume, no performance advantage.
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