SSHD question

[sfphoto]

Am thinking of getting a MacMini w/ an installed SSHD.

Would use for Photoshop and would partition the drive so that an empty partition could be used for a scratch disc. I have always done such since reading the instructions at Adobe's web site.

Read this and wondered what happens if I partition the drive?

SSHD stand for solid-state hybrid drive. It's a traditional hard disk with a small amount of solid-state storage built in, typically 8GB or so. The drive appears as a single device to Windows (or any other operating system), and a controller chip decides which data is stored on the SSD and what's left on the HDD.

Thinking also a Fusion drive would be similar.

Comments appreciated.

(OS10.12)

 

[techwarrior]

I have used SSHD on a few Macs over the years, including the one I am relying to this question from.

They do in fact look like a traditional HDD. The SSD portion is in fact a small amount of cache that the drives internal controller uses to speed read\write. The drive may be partitioned like any other drive, but the SSD part would generally only be used for the boot partition unless the files on the second partition are used very often.

They are faster than HDD, slower than SSD or Fusion, but they are much more affordable than SSD for similar capacities.

I believe with Fusion drives, they only use the SSD portion for the boot partition. Anything on a second partition would be handled like a traditional HDD, including boot camp.

 

[sfphoto]

Thanks TechWarrior

If partitioning I would assume that the SSD portion would be in the first partition (by default of the drive design) so the OS and applications should be placed there and other partitions for other files or scratch disk.

 

[campyguy]

Agreed with the above recommendation, chiming in with a humble clarification. Adobe - for PS - offers that the boot drive should be used as a scratch disk if the drive is an SSD. I tried an SSHD in my 2012 Mini Server for a bit, ended up going with an Samsung 840 Pro (now 850 Pro) with a Samsung T5 DAS.

"If your startup disk is a hard disk, as opposed to a solid-state disk (SSD), try using a different hard disk for your primary scratch disk. An SSD, on the other hand, performs well as both the primary startup and scratch disk. In fact, using an SSD is probably better than using a separate hard disk as your primary scratch disk."

Not nitpicking, the SSHD was as slow as the original spinner much beyond boot up and app launches. My 2¢.

 

[chabig]

As campguy quoted from Adobe, there will be no benefit to partitioning off a scratch partition. On an SSD it's not necessary. On a spinning HD you don't get any performance improvement. Having a scratch disk only makes sense when you can dedicate a device.

 

[sfphoto]

chabig wrote: "Having a scratch disk only makes sense when you can dedicate a device."

I had thought that any files residing in the scratch disc get fragmented, hence part of the reason for an empty partition.

As to a "dedicated device" perhaps an option to partitioning would be an external SSD connected via USB3 or FW800. Would not need to be large, what 5x the size of the largest files one works on w/ PS?

 

[techwarrior]

Thanks TechWarrior

If partitioning I would assume that the SSD portion would be in the first partition (by default of the drive design) so the OS and applications should be placed there and other partitions for other files or scratch disk.

Nope, for all practical purposes, there is no SSD on hybrid drives. Think of it as HDD but with an SSD cache to speed it up a bit. Partition would just allocate space for a separate mount point.

Btw, replacing the Mini HDD with SSD is pretty easy if you follow ifixit. Just did that on a 2014 Mini a few weeks ago with a 1TB SSD.

 

[chabig]

I had thought that any files residing in the scratch disc get fragmented, hence part of the reason for an empty partition.

As to a "dedicated device" perhaps an option to partitioning would be an external SSD connected via USB3 or FW800. Would not need to be large, what 5x the size of the largest files one works on w/ PS?

I think fragmentation is going to occur whether you use the main or a second partition. On modern file systems (like APFS) partitioning is purely logical, so you can't control where files go. If you do go with a dedicated device, I think an external SSD would be an excellent choice.