Hybrid drive temps

Got a question about hard drive temps.

I used to have a WD raptor drive as a cache drive how ever this drive started to fail and so I replaced my Cache drive with a Hybrid drive. 

I put the Hybrid drive in the "Ice pack" from the raptor drive and placed it into the unraid.

This drive is always at least 10 degrees lower then all of the other drives (Which I am not complaining about at all, but it always reads 24 to 25 degrees)

Is this pretty common because it's reading and writing from the SSD part of the drive or is it because I placed it in the "Ice pack" from the raptor drive?

Or maybe because it is a smaller "Laptop" drive it just runs cooler?

This is the first experience with these types of drives and any input would be greatly appreciated!

Most likely it's the "ice pack" cooler that's helping ... in addition to the much better airflow around the drive, since it's so much smaller than your other drives.  Laptop drives do NOT inherently run cooler than their desktop cousins .. in fact, in actual use they're often warmer, due to the very cramped mounts in laptops with relatively poor airflow.    But when mounted in a case with excellent airflow -- AND with the excellent conductive cooling the "ice pack" adds -- it's not surprising that it's running at such good temps.

... It's very unlikely you're just using the SSD part of the drive.  Writes would in fact still spin up the physical platter to do the actual write; and reads are unlikely to be limited to what's in the SSD cache.

Honestly I don't think that I have written anything larger then the 8GB of SSD storage on it... but I also have my mover moving the data over ever like 3 hours... Maybe I should update that now that I am thinking about it. Cause the only reason I had the mover working that often is because I could fill up a 130gig rapter drive in a 3 hour period (Not had with a 1Gbps connection lol) 

Has anyone used one of the 4TB hybrid drives as a Parity drive?

Cause my next upgrade is going to be a 4TB drive when I get the chance to go there.

Doesn't matter if you've ever written more than 8GB ... the SSD serves as a cache -- anything you write to it is automatically written to the spinning platter part of the drive as well, so it's still spinning.

Using a 4TB hybrid drive for parity would have almost no benefit, since the parity drive isn't file-based, but will be very randomly accessed based on where on the other drives you're writing data to.

Has anyone used one of the 4TB hybrid drives as a Parity drive?

Cause my next upgrade is going to be a 4TB drive when I get the chance to go there.

I'm using one for my mp3 drive. Impetus being, since I have 400,000 files, at least the directories would be stored in the 8GB cache.

Reality is, I've yet to see this theory proven. I question if the premium for the drive was worth it as it's not all that much faster then the drive it replaced when sweeping the directories.

I know as a point of reference with various programs that all of the stat information and  directory information should take less then 1GB.

So my recommendation would be that the premium on a parity drive is better spent on a 7200 RPM drive.

While a parity check will only go as fast as your slowest drive, a parity create will be faster. I've benchmarked that.

In addition, when doing parallel writes to multiple drives, the faster parity drive will be provide a slight boost.

Last but not least, and probably most important, if your array is not too wide (many disks) and you have turbo write enabled, writes are faster when writing to a single drive at a time.  If you have a wide array with many drives, this point is doesn't come into play.

Using a 4TB hybrid drive for parity would have almost no benefit

Agreed.

since the parity drive isn't file-based, but will be very randomly accessed based on where on the other drives you're writing data to.

This part is partially true and partiality untrue.

The Hyrbrid drives by Seagate cache LBA's not files. The most often used LBA's are cached. This is at a lower level then the file.

Directory scans on my laptop Hybrid drives are so much faster after a few days with the hybrid drives.

My DJ laptop with tons of mp3's shows a huge benefit just in directory scans alone.

The Hybrid drive would be of benefit on a cache drive that is used as an APPS drive. There could be a slight benefit in parity operations, however with the amount of writes going on, I doubt the cache would be of much use.

If there is a read occurring on the hybrid drive, it most certainly is going to be written to. That write is going to be a write through. The next read may benefit slightly, but the next write wont.

In theory if the superblock of all the drives were in the same place I.E. if all the drive models were exact, there could possibly be a benefit in reading the superblock and journal. I'm not sure it's measurable or worth the premium.

I wouldn't put the hybrid drive in the parity slot.  However if it is done, I would be very interested in the results.

Agree that a hybrid cache drive would likely be beneficial if its used as an apps drive.

As for parity, it's simply not worth the bother.    For that matter, even an SSD parity drive [perhaps a RAID-0 array of a few 1TB SSDs to make a 3 or 4 TB "drive] would likely not be as much of an improvement as you might think.    It would have little impact on typical one-at-a-time writes (since the system would still be waiting for the read/write cycles on the involved spinner) ... but it could indeed have a very nice impact if you often have multiple writes being done at the same time to different data drives, since there's be almost no extra delay due to parity operations in multiple locations.