Using a SSD drive to store masters

[manuelsechi]

Hello all

I need to move all my images to an external drive, and I was suggested to keep the catalog file (Lightroom Library.lrlibrary) on the local drive.

What benefits can I expect to see using an external SSD drive over a traditional HDD to store the masters? I know LR works on the catalog so can I expect to have LR fast enough to work or my images on just when importing files from my memory card?

thanks

[dj_paige]

"What benefits can I expect to see using an external SSD drive over a traditional HDD to store the masters?"

Virtually none.

A traditional HDD to store the original photos is fine and will not cause any noticeable slowness.

[manuelsechi]

not even when writing the .xmp file?

[Ian Lyons]

If you're writing metadata to XMP, DNG or a rendered image (JPEG, TIFF, PSD), then yes storing them on an SSD will be benificial.

[dj_paige]

Why do you say that, Ian? Writing to XMP is a trivial amount of data, I'd be surprised if anyone can notice a difference between writing XMP to the SSD versus writing XMP to external spinning hard disk.

[Ian Lyons]

It's trivial for one image, but 100, 1000, 10,000. Even writing metadata to the catalog on SSD can be painfully slow when large numbers of files are involved

[dj_paige]

"It's trivial for one image, but 100, 1000, 10,000. Even writing metadata to the catalog on SSD can be painfully slow when large numbers of files are involved."

You wouldn't, on a regular basis, update hundreds or thousands of XMP files in one action. In normal LrC usage, you edit a photo or add metadata to a photo, that one XMP file might get updated (if the option is turned on), and it happens very very quickly, you would not notice a difference between updating on a regular old external disk and an SSD.

Even when I come home with say two hundred photos, and after import they all get assigned a caption of "Buffalo, NY", I barely notice the time it takes to do this (and I do not have an SSD for my photos).

[Conrad C]

An XMP file (and I assume a catalog database record update for one raw file) is typically under 20KB. That’s almost nothing, so when writing a single .XMP file, it would be very hard to notice the difference between a hard drive and an SSD. Even with a hard drive it only takes a brief moment.

When reading or writing many .XMP files, an SSD would be faster, but it won’t be transferring at its top rated speed. The reason is that when copying many small files, there’s more overhead. 1GB of many small files will always take much longer to copy than a single 1GB file. So an SSD would still be faster than a hard drive in that case, but not as much as one might think from looking at its specs.

What Lightroom Classic probably spends the most time reading and updating are the previews. The read/writes for the catalog or .XMP files are a small amount of data per image, but a preview can be several MB per image depending on the preview settings and display size. Because the preview file lives next to the catalog file, that’s one reason it’s suggested that the catalog be on a fast SSD, and the raw files (and .XMP files, if used) are OK on a hard drive.

[GoldingD]

LrC performance vs Hard Drives

The catalog can benefit from being on a fast hard drive

The Camera RAW CACHE can benefit from being on a fast hard drive

The Camera RAW CACHE on a Windows OS can  benefit by not being on the same drive as the OS Paging file

The Photos storage location does not general benefit from being on a fast hard drive

The actual program, and the various support files do not benefit from being on a particular drive.

Catalogs cannot be on a network volume such as NAS

Photos can be anywhere.

[Michael J. Hoffman]

Keeping the catalog and the originals on the same external drive makes a good portable solution that you can move from one computer to another, or offload storage space from your internal drive of a laptop. However, LR reads and writes continuously and heavily to the previews cache located in the same location as the catalog. If the catalog, previews and originals are all on a single external drive connected by USB, you'll likely saturate the USB bandwidth and will see some performance hits. This doesn't matter whether the external is a spinning hard drive or SSD, the USB channel will be the bottleneck. It's a tradeoff of convenience vs performance.

[manuelsechi · Accepted solution]

OK, so I'll move all the files (.raw) in a traditional external 7200 SATA disk and I'll keep the catalog in my local Pictures folder (MacOS).

thanks everyone for your help.

M

[DdeGannes]

It has always been my understanding that Lightroom's primary function is to read and write to the Catalog file, update Previews, RAW Cache etc. Writing to XMP is an option and is a secondary function which is not prioritized. Storage on the external 7200 Sata disk, should be fine.

Better to have a larger capacity HHD with lots of storage than an SSD with limited free disk space. 

[Michael J. Hoffman]

That's true about deprioritizing XMP data, but remember that the originals do need to be read to generate previews, and smart previews.

Worst case scenario: Imagine importing from a card connected to a USB, copying those images to a HD on USB, and then reading all the images to generate full size previews and (potentially) smart previews. That's a lot of USB traffic, even if the catalog is on your internal drive.  If you don't generate Smart Previews, then the original has to be read again on the fly when you go to the Develop module to work on an image (can be avoided if you created the Smart Preview in advance).

[DdeGannes]

Michael all your points are valid, importing image files to an external drive connected via USB, HHD or SSD, will take longer than importing to an internal drive period.

When I purchased my existing system in mid-2015 I decided on an HHD with 3 TB of capacity ( an SSD 500 GB would have been a similar cost) so it could store all the files necessary files including image files for running Lightroom Classic.

My Original image files require approximately 600 GB of disk space, and I presently have, 2.2 TB of free space.

Backup storage is on two external disks one 1 TB and the other 2 TB.

Quote ” but remember that the originals do need to be read to generate previews, and smart previews.” my thoughts here is that reading is not going to cause slowdown as much as writing.

I do not write to XMP nor use DNG by personal choice, things just keep humming along.

[dj_paige]

"Worst case scenario: Imagine importing from a card connected to a USB, copying those images to a HD on USB, and then reading all the images to generate full size previews and (potentially) smart previews. That's a lot of USB traffic, even if the catalog is on your internal drive. If you don't generate Smart Previews, then the original has to be read again on the fly when you go to the Develop module to work on an image (can be avoided if you created the Smart Preview in advance)."

The vast majority of the time involved here is CPU time. The disk access time and transfer time is small compared to the CPU time.

[Michael J. Hoffman]

Right you are, DdeGannes, but to the original poster's questions, whether an SSD will have a benefit over a traditional spinning hard drive, I think the main point is that the USB interface will be the bottleneck, even for a spining drive. So, for me, I don't see a huge speed benefit with external SSDs connected to USB. They do win in terms of robustness and size/weight, and someday soon, will win on price, too.

[DdeGannes]

I concur with the USB link being the main impediment.

[Just Shoot Me]

Not really true anymore with the USB C connection speeds. Sure a little slower that internal SATA or whatever they are using now.

But in years past the bottleneck was always the HDD.

[Conrad C]

I’m more with Just Shoot Me on this one. USB is not necessarily the bottleneck if you shop carefully.

5 Gb/sec: USB 3.0, 3.1/3.2 Gen 1

6 Gb/sec: SATA — the interface for internal hard drives and older SSDs

10 Gb/sec:  USB 3.1/3.2 Gen 2

So if your components and cables all support 10Gb/sec USB 3, you’ve got an interconnect with a much higher spec than the connector on a common 6Gb/sec SATA hard drive or SSD. 10Gb/sec USB 3 should not be the bottleneck for a spinning drive. It’s enough bandwidth to handle requests from multiple SATA drives at once.

(Keeping in mind that all of those operate much slower than the spec in the real world due to overhead, CPU load, and other factors)

I specifically bought a 10Gb/sec USB 3 multi-bay enclosure to minimize the chance that USB 3 would be the bottleneck for the drives inside it.

In that worst case scenario of simultaneous multiple requests from an external hard drive, 10Gb/sec USB should have no problem since it’s faster than 6Gb SATA, but that hard drive would be severely delayed by the heads running back and forth across the platters to serve each request. In that case a hard drive should be much more of a bottleneck than USB or SSD.

Edit: Just remembered one more thing…I recently picked up an NVMe-based SSD in an external enclosure as a fast travel backup for my MacBook Pro. The NVMe enclosure supports 10Gb/sec USB over USB-C. NVMe is not limited to 6Gb/sec like SATA is. Like others of its type available today, it is capable of more than 900MB/sec read/write over 10Gb/sec USB, and I’ve measured that on my laptop. That’s 8-10 times faster than most hard drives, over USB.

(900 megabytes per second is 7.2 gigabits per second, out of the theoretical 10Gb/sec of USB 3.x Gen 2.)

With that level of throughput, today’s USB is not going to bottleneck multiple hard drives, if you carefully match what you buy with what affordable 10Gb/sec USB 3.x Gen 2 is capable of.

[Just Shoot Me]

Eventually the only hard drives, Storage Devices, made will mostly be SSD's. When that happens the cost of new Spinning HDD will go up and become obsolete just like floppies and CD/DVD drives and discs.

So there is NO reason not to place any files on SSD's and or if you have the funds to spend go righ ahead and buy whatever storage devices you want.