will SSD + HDD = performance bottleneck?

[cooa99]

I have a mac mini server with 2 HDD and thinking of swapping to SSD.

500GB Boot drive contains the OS and just a handful of apps ... all under 30GB size
2nd 1TB Drive contain my working files + virtualbox/vmware virtual machines ... about 550GB in all.

My plan is to just upgrade the 2nd drive to SSD to get a better performance out of the VM's


So my question is will there be a huge performance gain to this approach or will OS drive on standard HDD simply nullify the performance boost?

 

[jpietrzak8]

So my question is will there be a huge performance gain to this approach or will OS drive on standard HDD simply nullify the performance boost?

The biggest bonus in terms of SSD vs HDD is latency -- that is, how fast off the mark the drive is in starting to return data. Once data is streaming off the drive, the advantage of the SSD is reduced. So, what you want on the SSD are:

1) Apps (including the OS): This is the feature that folks on this board tout the most, as an app has less "beachball" time when you start it. Particularly useful for folks who are constantly turning their machine off and on over and over, or closing and reopening the same apps over and over...

2) Small files: if you have large numbers of small files on your drive, an SSD can access them much more quickly than an HDD, as the HDD may need to spend a lot of time seeking between files. For example, a large library of photos can benefit greatly from the SSD.

3) Large databases: Any application that needs to access data across a wide database will benefit from the SSD, for the same reason as a large number of small files would: reduced seek time to retrieve bits of data scattered across the database.

On the other hand, large monolithic blocks of data that are accessed serially (for example, music or video media) benefits very little (if at all) from being on an SSD, as latency is normally not an issue here.

So, that's pretty much the guideline for dividing data between SSD and HDD: if you can, place your apps and your seek-heavy data onto the SSD, and keep serialized data on the HDD...

 

[treekram]

What model (year, quad vs. dual) mini do you have and what OS are you using?

I have 3 minis - 1) late 2009 with an upgraded SATA II 7200 rpm HDD, 8GB RAM running Snow Leopard; 2) 2012 quad core i7 16GB RAM which originally had ML with the original HDD, now has an SSD running El Capitan; 3) 2014 mid, 8GB with the HDD and El Capitan.

What I have noticed is that, for whatever reason, the 2014 Mini, which is mainly used as a DVR and some Handbrake, experiences lag in starting up applications and when the apps compete for the disk, more so than the 2012 Mini did with ML and the HDD but also more so than the 2009 Mini (which was the DVR computer before so what I was doing there was pretty comparable). Besides the DVR application, the applications I'm talking about are pretty basic ones - System Preferences and Text Edit in particular. I think that in the OS design, it is now presumed more people have SSD's? I have an Thunderbolt SSD on order for the 2014 Mini but it will take some time before I get to actually testing it and seeing how performance improves.

I don't have VM's running but I think definitely having them on the SSD will result in a noticeable difference. Moving the apps the SSD first, as jpietrzak8 suggested, is a good idea. If you feel the system still lags at times, you can move the OS there although that will take more work.

 

[cooa99]

Thanks guys,

I have the 2012 Quad Core i7 mac mini with 16GB ram as well ..... now updated to El capitan.

The mac mini runs headless since its existence is purely to run other windows vm and a plex server


My main issues are with the running VM's

It seems that they have gotten worse over time with every OSX since Mountain Lion.

I guess the only way forward is to use an SSD.

 

[treekram]

What you're seeing with performance degradation seems to match my anecdotal experience - whether that's the case or not - I don't know.

Some things to keep in mind:
- Changing out the HDD for an SSD in the 2012 Mac Mini is not trivial - there are numerous examples on macrumors of people who have broken something in the process (I was able to do it without breaking anything). Definitely do your research before changing it.
- I think it's a good idea to run the SSD externally at first (or even permanently?). That way you can see if you want to put just VM's on the SSD or the OS as well. In any case it's a good idea to make sure everything works before putting the SSD into the computer. My experience was that my 3 docking stations didn't work - but an old cheap USB2 drive enclosure did! Obviously that wouldn't work for what you want to test but the caveat is that USB3 can be fickle and you may need to buy an additional enclosure/dock to test it out externally.
- Do the research on how to transfer the VM disk to the SSD. Cloning the drive will certainly work - I don't know if you can just copy the files.

 

[cooa99]

I have taken the Mac Mini apart a couple of times so should not be a problem ..... just not fun getting to the 2nd HDD though.

My Mac Mini is Bolted to the back of my LCD TV. I can hear the fan kick in when using handbrake or multiple torrents downloading within a vm.

while not an issue, would moving to SSD reduce this drastically?

cheers

 

[jpietrzak8]

My Mac Mini is Bolted to the back of my LCD TV. I can hear the fan kick in when using handbrake or multiple torrents downloading within a vm.

while not an issue, would moving to SSD reduce this drastically?

Well, the fan kicking in shows that the machine is getting very hot, which can be an issue. I don't know about the torrents, but Handbrake is a very CPU-intensive application. It would really make no difference at all whether the device had a HDD or an SSD, the CPU will still get hit just as hard, and this will heat up the machine.

I think the easiest technique you could use to keep the machine a bit cooler would be to remove it from the back of that TV. Placing the Mini in an area all by itself, with sufficient air flow around it, would probably help. Possibly placing it on its side would be a good idea as well, to increase the surface area exposed to the air...

 

[treekram]

On my i7 quad, the input is usually an external disk and the output is the internal HDD. I'm pretty certain using the SSD instead would not noticeably reduce fan usage. On my dual-cores, I have never heard the fans when doing Handbrake even though the input/output is the internal HDD probably half the time. I don't do torrent downloading but my guess is that if you use SSH, that takes processing power plus whatever VM overhead you have.

I know people have expressed concern about the i7 heat but 3 years after being introduced, I have yet to see a post here about anybody actually experiencing an actual processor meltdown due to 2012 i7 heat. I think if there's sufficient airflow and it's not where the LCD is generating a lot of heat, you're OK. The Mini will take steps to mitigate high temperatures. There are steps that people have taken to reduce the noisy fan usage (introducing external cooling, changing the fan speed profilec, etc.).

 

[cooa99]

Thanks all.

I have ordered 250GB & 1TB Samsung SSD's so will see how I get along with that.