# Keeping photo library on a nas super slow even with top nas and directly wired via gigabit Ethernet



## Sean Michael (Jul 30, 2016)

I'm trying to using a nas to store the Lightroom image library but it is super duper slow! I have a very fast synology nas ds716+ , a super fast  Mac book pro 2015, and bt home hub 5. I have gigabit Ethernet via fiber optic cable. Even when it's all connected wired, nas to router , Mac to router using gigabit Ethernet pluged in into macs thunderbolt port, it's still very slow taking forever to load up all the previews on even a single folder of 50 images.o to half the images will just stay greyed out until you click to open them individually- then you can see them and work on them . Doesn't seem to be a viable option ? Not sure why people Are endorsing it?


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## Johan Elzenga (Jul 30, 2016)

*DON'T STORE THE LIBRARY ON A NAS!!!* You run the risk of library corruption beyond repair. The Lightroom library is based on SQLite, which is not compatible with networked drives. You can store the images on the NAS, but not the library.


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## Sean Michael (Jul 30, 2016)

Hi Yes Im talking about the images.. its the catalogue that you cant keep on the NAS (must be local) but the library is the images...?


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## Johan Elzenga (Jul 30, 2016)

Sean Michael said:


> Hi Yes Im talking about the images.. its the catalogue that you cant keep on the NAS (must be local) but the library is the images...?



OK, semantics. Aperture calls it a library, Lightroom a catalog, so if people talk about 'library' in relation to Lightroom, I assume they mean the catalog. As long as you understand it.


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## Sean Michael (Jul 30, 2016)

ok so is it catalogue and images? so i mean images - they are super super slow


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## Gnits (Jul 30, 2016)

A typical retail NAS networked solution  cannot compete with disk drives connected directly to a motherboard bus and current evolution of M2 and PCIe connections make the comparision even more extreme.  Also, Networks measurements are in bits per second (small Mb or Gb), while we are more used to  Megabytes(MB or GB). For example the Intel 750 Series AIC 400GB PCI-Express 3.0 x4 MLC Internal Solid State Drive (SSD)  (Intel 750 Series AIC 400GB PCI-Express 3.0 x4 MLC Internal Solid State Drive (SSD) SSDPEDMW400G4X1 - Newegg.com ) has a sequential read speed of 2200 Megabytes per second. Your network connection has a max throughput of 125 Megabytes per second, before networking overheads at all junctions is taken into account.  Copy 100 raw files (from and to) your Nas from your Mac and time how long it takes and calculate the Megabytes per second just to move data between the devices.  Then you have to factor in raw conversion or any other processing which needs to be done by Lightroom.

NAS devices have their role but they are constrained by the max speed of the network, the speed of the Nas drive itself and the speed of the individual disks inside the Nas.


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## Johan Elzenga (Jul 30, 2016)

What you describe (slow thumbnails) should have nothing to do with where the images are. The thumbnails are in the <Lightroom catalog> previews.lrdata and those are in your Lightroom catalog folder. Even if the images are offline you should be able to see the thumbnails. The images are only needed if the thumbnails need to be rebuilt for some reason.


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## Gnits (Jul 30, 2016)

The various previews may have to be rebuilt because of all the copying of images from folder to folder.


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## Johan Elzenga (Jul 30, 2016)

Gnits said:


> The various previews may have to be rebuilt because of all the copying of images from folder to folder.



That should be no reason to rebuild previews.


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## Gnits (Jul 30, 2016)

Surely, if a lot of images have been moved outside of Lightroom there must be orphan previews left behind while at the same time a lot of previews need to be rebuilt.


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## Johan Elzenga (Jul 30, 2016)

Gnits said:


> Surely, if a lot of images have been moved outside of Lightroom there must be orphan previews left behind while at the same time a lot of previews need to be rebuilt.



Orphaned previews only need to be deleted, but they won't be deleted until you delete the database entry. As far as Lightroom is concerned, they are not orphaned, the original is missing. And I don't see why a preview would have to be rebuilt if the image has only been moved to another location. Previews are built on import, and rebuilt when you edit the image. Maybe the OP has a lot of imports with previews that have not yet been built?


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## Gnits (Jul 30, 2016)

JohanElzenga said:


> Maybe the OP has a lot of imports with previews that have not yet been built?



Exactly.


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## Jim Wilde (Jul 30, 2016)

JohanElzenga said:


> What you describe (slow thumbnails) should have nothing to do with where the images are. The thumbnails are in the <Lightroom catalog> previews.lrdata and those are in your Lightroom catalog folder. Even if the images are offline you should be able to see the thumbnails. The images are only needed if the thumbnails need to be rebuilt for some reason.



My turn to say "exactly"! And even if previews had not been built during import, the fact that the images are on a NAS shouldn't add all that much to the preview rendering time (most of the activity is CPU-bound, not I/O bound). Just as an example, I compared the time to render 1:1 previews for 100 of my 5DIII raw files after moving them to my NAS, with the time it takes when the images are on a USB3-connected G-tech drive (7200 rpm). With the images on the NAS, the per image preview time was 3.05 seconds, compared with the 2.40 seconds when the images are on the G-Tech. 

Sure, importing will be a little slower if copying to a NAS, but once they're there there should be very little in the way of a performance hit. I've previously tested with images on an SSD and a 5400 rpm portable external drive. There really isn't that much difference, and with the new improvements in LR6.6 (image pre-loading in Develop) there's even less notable difference....CPU is the main influence.


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## Gnits (Jul 30, 2016)

If there is a grid or multiple grids of images which need previews built it will still take time.  

It would also be useful to see what is the copy time from the Nas. 

Given that there is a history of large scale image movements  between folders outside Lr, I would be tempted to clear the previews and rebuild them overnight.


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## Johan Elzenga (Jul 30, 2016)

Gnits said:


> If there is a grid or multiple grids of images which need previews built it will still take time.
> 
> It would also be useful to see what is the copy time from the Nas.
> 
> Given that there is a history of large scale image movements  between folders outside Lr, I would be tempted to clear the previews and rebuild them overnight.



I don't understand your preoccupation with those image movements. Moving images doesn't trigger rebuilding of previews. Only fresh imports or image editing does. Yes, he moved images around outside of Lightroom, but that by itself doesn't explain what he is seeing. And if he needed to re-import a lot of images as a result of those movements, that still should not cause what he describes. Read the comparison Jim made.


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## Sean Michael (Jul 30, 2016)

Thanks very much for the insights. Id like to believe there was hope for using lightroom on a NAS. AS I say I was surprised that even when hard wired to my router it didn't help much.

I have still have not got my head around how or why to set thumbnails and previews at 1:1 and what thats all about.

I have noticed my few small .mov files are all struggling  with the previews. Also where the thumbnails are not showing its very laggy and jerky and hard to scroll down. I did keep moving things around outside light-room and the deleting the catalogue and starting again, just as i find it really hard doing lots of intensive reorganisation in light rooms interface,  you can't open out the folder structure in LR in a couple of windows for free movement like you can in the finder.

ps. I'm running Lightroom 5.6..

Im happy to try 'clearing the previews and rebuilding them' can you please indicate how to do it   ??

Thanks..


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## DGStinner (Jul 30, 2016)

I'm using a NAS to store my images and I don't have any noticeable lag compared to when they were stored on a Thunderbolt external.  Are you sure your MacBook is using the wired connection?  If wifi is turned on, it may still be using that even though you plugged in a cable.  
Your NAS has 2 network ports.  Are you using only one or have you configured trunking?  Have you tried upgrading to the latest version for v5 which is 5.7.1?


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## Sean Michael (Jul 30, 2016)

Hi, Yes I disabled the Wi-fi and checked the internet was working fine without the wi-fi. Yep my NAS has 2 ethernet posts (DS716+ii) - I cant configure trunking/ dual aggregation as my macbook pro has no ethernet ports so I had to buy a thunderbolt to Gigabit ethernet adaptor. Still loads of previews loading very slowly. 

Actually I had an idea - My macbook pro had 2 thunderbolt ports so I wondered if those 2 can be turned into 2 ethernet post for dual aggregation? ( I read the computer needs 2 ethernet ports to do it) I doubt that will work though.


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## Johan Elzenga (Jul 30, 2016)

I'm beginning to wonder if you have catalog corruption causing this. As several people explained, having images on a NAS shouldn't cause slow loading of thumbnails. Try this: create a brand new Lightroom catalog and import a few hundred images from that NAS. See how fast that goes. If it is as slow as your current catalog, then there is a problem with the NAS. If it is much faster, then there is a problem with your current catalog.


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## Sean Michael (Jul 31, 2016)

Hi thanks for that. I don't think either of these are correct. this is a newly made catalogue. I have created several catalogues from the same images and each one has had the same problem. Also this is a new was and I have tried 3 NAS lately - I even replaced this NAS last week with a new version of the same NAS last week and it still did the same problem.


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## Gnits (Jul 31, 2016)

Can you copy 100 raw files from your Nas to your Lr machine, tell us how long it took in minutes and seconds and the total size in Megabytes of the 100 raw files.

I would just like to get a baseline of the actual speed from Nas to Mac.


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## Gnits (Jul 31, 2016)

JohanElzenga said:


> I don't understand your preoccupation with those image movements. Moving images doesn't trigger rebuilding of previews. Only fresh imports or image editing does. Yes, he moved images around outside of Lightroom, but that by itself doesn't explain what he is seeing. And if he needed to re-import a lot of images as a result of those movements, that still should not cause what he describes. Read the comparison Jim made.



I am not disputing the length of time between SSD and NAS to process individual images when in develop mode. The time to load an individual raw file is not significant here.



Sean Michael said:


> it's still very slow taking forever to load up all the previews on even a single folder of 50 images.o to half the images will just stay greyed out until you click to open them individually-




This reads to me that the previews have not been built yet..... which might happen if a lot of images have been imported and yet to be create the previews .... which is slowed down by a slow connection to the Nas, especially when there is a large pipeline of previews to be built.

It would be useful in such a case to quantify the actual rather than theoretical speed between the NAS and the Mac.


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## Gnits (Jul 31, 2016)

Sean Michael said:


> Im happy to try 'clearing the previews and rebuilding them' can you please indicate how to do it  ??



The preview cache may not be the problem, but in an effort to eliminate as many variable as possible here is a link to an article by Victoria. You mighty try this late in the day and let the re build of previews take place overnight.

Lightroom says my preview cache is corrupted—how do I fix it? - The Lightroom Queen


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## Johan Elzenga (Jul 31, 2016)

Sean Michael said:


> Hi thanks for that. I don't think either of these are correct. this is a newly made catalogue. I have created several catalogues from the same images and each one has had the same problem. Also this is a new was and I have tried 3 NAS lately - I even replaced this NAS last week with a new version of the same NAS last week and it still did the same problem.



Maybe it's your thunderbolt to ethernet adapter then... Or something else in that chain (cable, switch).


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## Jim Wilde (Jul 31, 2016)

Why not take the NAS out of the equation temporarily? Create a new catalog, import a couple of hundred images onto a non-NAS drive, build standard previews during the import, wait for that to finish, then see how the catalog performs.


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## Sean Michael (Jul 30, 2016)

I'm trying to using a nas to store the Lightroom image library but it is super duper slow! I have a very fast synology nas ds716+ , a super fast  Mac book pro 2015, and bt home hub 5. I have gigabit Ethernet via fiber optic cable. Even when it's all connected wired, nas to router , Mac to router using gigabit Ethernet pluged in into macs thunderbolt port, it's still very slow taking forever to load up all the previews on even a single folder of 50 images.o to half the images will just stay greyed out until you click to open them individually- then you can see them and work on them . Doesn't seem to be a viable option ? Not sure why people Are endorsing it?


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## Johan Elzenga (Jul 31, 2016)

Gnits said:


> The preview cache may not be the problem, but in an effort to eliminate as many variable as possible here is a link to an article by Victoria. You mighty try this late in the day and let the re build of previews take place overnight.
> 
> Lightroom says my preview cache is corrupted—how do I fix it? - The Lightroom Queen



The OP answered me that he tried different catalogs, so the preview cache of one of those catalogs isn't the problem, period. I agree with Jim. You have to trouble shoot this methodically. Eliminate the NAS first and see if Lightroom works fine with a local drive. If that works fine, see how the NAS performs itself (copy images from the NAS to the internal disk in the Finder, for example). Go step by step, don't try all kinds of possible solutions all at once.


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## Gnits (Jul 31, 2016)

Jim Wilde said:


> Why not take the NAS out of the equation temporarily? Create a new catalog, import a couple of hundred images onto a non-NAS drive, build standard previews during the import, wait for that to finish, then see how the catalog performs.



It is a good idea to take the NAS out of the equation, but before you go back to testing the NAS please test the actual throughput from NAS to Mac.  This link needs to be eliminated from the list of possible problem sources.  Doing a ping test will only test connectivity and give you a response in millisecs.  A basic measurement of Megabytes per second under sustained load is needed.  The problem could be anywhere in the network link.


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## Gnits (Jul 31, 2016)

JohanElzenga said:


> The OP answered me that he tried different catalogs, so the preview cache of one of those catalogs isn't the problem,



Agreed.... I was answering the earlier question regarding clearing the preview cache and Victoria's answer is the best there is.


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## Sean Michael (Jul 31, 2016)

Hi, I transfered 100 Cr2 files (total 25.22 GB) from NAS to Mac via finder. Just now, took 42 seconds - using WI-FI


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## Sean Michael (Jul 31, 2016)

Today the wi-fi seems very snappy, this morning. What I notice today with much snappier Wi fi  speed is that many previews are blank to start with, but the blank ones eventually appear if I keep them visible in the window then then appear in 5 - 60 seconds. I then hover over the next lot of blank ones and then they appear after a while to. So Im thinking its not a case of missing previews....  Maybe its bandwidth.


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## Gnits (Jul 31, 2016)

Sean Michael said:


> Today the wi-fi seems very snappy, this morning. What I notice today with much snappier Wi fi  speed is that many previews are blank to start with, but the blank ones eventually appear if I keep them visible in the window then then appear in 5 - 60 seconds. I then hover over the next lot of blank ones and then they appear after a while to. So Im thinking its not a case of missing previews....  Maybe its bandwidth.



I expect so.  That is what I was trying to eliminate at the start by doing the calc of actual throughput.    I have used Excel to calculate based on the numbers you supplied.

I suspect that the total Megabytes copies is 2522, not 2.522 GB.





Assuming you copied 2522 Megabytes, then you will get 60 Megabytes per second throughput.  If Lr has to build previews for say 30 images it will take at least 15 seconds to copy these files to Lr (and Lightroom will also need time to process these files).




The best thing to do is make sure that all the previews are built for your catalog and then explore grid view again.

On your main catalog you may have lots of images which do not have previews.  Given the history of file movements related to this catalog, I would be temped to use Victoria's procedure to rebuild all previews for your main catalog (maybe overnight).

60 MB per second means that you should have ok performance in Develop mode, developing individual files and then moving to the next file to develop, but if you are syncing changes across a lot of files then bandwidth is likely to be a factor in terms of refreshing the results.

This performance behaviour is the reason many people develop their current stuff from a local drive and use the NAS for older images.


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## Sean Michael (Jul 31, 2016)

Thanks Gnits - sorry the total transferred was 1.6GB - screenshot attached


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## Sean Michael (Jul 31, 2016)

see attached


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## Sean Michael (Jul 31, 2016)

could yu recalculate that with the new figure? i will try rebuilding previews. also first I will copy all the images from NAS to HDD and mae a new catalogue for it to compare the performance.


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## Gnits (Jul 31, 2016)

Ok.... I have reworked the calculation.



 

This is approx 2 raw files transferred per second.   To rebuild previews for 30 images will take at least 15 seconds, and longer depending on what other tasks Lr is doing at the same time.


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## Sean Michael (Jul 31, 2016)

Hi! Ok, so my transfer speed then is 300 Mbs, (I think it she megabits per second that everything g is measured in.... is that a decent speed?

Right - I transferred images over to HDD, made a new catalogue. I then also noticed that although many previews were pre populated in each folder that say 20% were not and were greyed out. Those greyed out ones didn't generally load up until I hovered over them and waited then they loaded quickly (quicker that the NAS). - but I did have to wait. I also noticed, once the previews had loaded in a particular folder, I could quit the program - open it back up and the images in that particulate folder would all be instantly pre loaded. It sees like once its loaded them all up they stay loaded (at least in the HDD). - but not sure why I have to hover over them to let it happen?


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## Gnits (Jul 31, 2016)

Creating Previews is a background task and takes a while to complete. Many people, after importing a bunch of images, find this is a good time for a coffee or to do something more productive and then return to Lr after the previews are built.


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## Gnits (Jul 31, 2016)

300 Megabits per second is one third of your 1Gb network bandwidth.  1 Gb is never reached in practice as there is always network overheads, intrinsic to the nature of networks,  to be allowed for.  Also, the processor in your NAS can only feed the pipe based on its speed and the speed of the disks in the NAS.

What is good about this number is that it is well above 100Mb per second, which eliminates the possibility that there is an old 100Mb card or switch in the mix.   I have found old slow cheap switches gaffer taped underneath desks that the user had no idea was there.

The good news is that you have numbers that you can relate to now and can figure out how to optimise the hardware you have. 

You can query Synology support as to what max throughout to expect over a lan.  You can also do a test with say a laptop which has a network port, which you can cable directly to your router, and repeat the test of copying your 100 raw files, so you can check if some of the network connectors at the Mac side are slowing network throughput.


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## Sean Michael (Jul 31, 2016)

Yea my point though is if I don't hover over the images is the window - they don't get built, even I I wait for ages And on the nas this process slows down to a grinding halt. I can rebuild the previews but can this help Even with  a fresh catalogue? I will Test this further on hdd but definitely inmanagable on the nas so far.

Can I ask you another question?.. Since you know about databases management ..

About 60% of my database is just images saved off the internet for teaching presentations or quick snaps on iPhone . I'm wondering if Lightroom is overkill for storing these images that I will never need to process / adjust. I'm wondering if they are slowing the Lightroom system down by adding lots more photos..

Would you advise keeping such images on a separate system like Mac photos or in my nas photo viewer which are lighter weight. I do need them carefully organizing in folders on some kind of darabase like my other images but thought maybe Lightroom should be saved for images i want to adjust to help it run better ?

 I would rather have everything on one system , - only Lightroom can do a good job of processing the other 40% so it needs to be partially or wholly on lightroom


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## Gnits (Jul 31, 2016)

There are a lot of points her.

1. Based on your profile, you are using an old version of Lr.
2. Lr performance will generally not be influenced by the number of images in the catalog.  I have 75,000, others have 3 times that.
3. If I was using Lr for 40% of my images, I would probably use it to manage all my images. Also, I would see no advantage to using two different catalogs.
4. I keep a lot of images in my catalog which are also used for training and other purposes and never get processed, although it is handy to find or export to different sizes or formats.
5. Grid view in Lr is not able to compete with other products such as PhotoMechanic or image browsers in terms of page to page speed. I used to use Breezebrowser a long time ago, but this is only a Windows product, but have stopped using it for some time.  Many photographers would like to see a fast grid mode within Lr. I used to use PhotomMechanic but stopped.


It takes a while for everyone to work out their own optimum workflow.  This will probably continue to evolve as both software and hardware provide new ways of wo King.

I think overall that Adobe have done a good job with Lr, but that does not stop me getting frustrated from time to time by lack of investment in the core Library module in terms of usability, some obvious mistakes which could have been avoided and the priorities of Adobe marketing.  I could go on, but I still pay for and use Lr.


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## Sean Michael (Jul 31, 2016)

ok.. so i upgraded to Lightroom CC and re imported everything from scratch on an external HDD in a new catalogue. Much quicker in terms of scrolling with no lag and previews building quicker. I do still have many previews not appearing until I scroll over them - at which point the load up very quickly but I can wait 30 mins and scroll down an bit to reveal more blank previews - which again load up instantly when revealed... 

NEW problem -  I let all my previews load but when I removed my HDD (had to force eject it), all the photos have now got a question mark on and although the previews are still there the photos cannot open. I don't get why Lightroom cant find them even though I plugged the drive back in. the trident happen with the NAS...


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## Johan Elzenga (Jul 31, 2016)

Sean, I really don't understand what you're trying to do. Why do you remove the HDD (even force ejecting it...) when that disk contains the images? Of course Lightroom can't find them anymore if you remove that disk! The previews are in your catalog folder (on your internal disk), so that is why Lightroom still shows those. Everything you describe is exactly what I would expect to happen, except that I don't understand why you're doing this in the first place...


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## Sean Michael (Jul 31, 2016)

Hi well its pretty simple. I cant keep my external HDD plugged in to my laptop forever! I needed to take the laptop away so unplugged the drive - and then tried to plug it in later and open the catalogue again to view the images. Seems like a very basic think to need to do? When I ejected my NAS this never happened - lightroom would just relocate the images again when the NAS was present.


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## Johan Elzenga (Aug 1, 2016)

Sean Michael said:


> Hi well its pretty simple. I cant keep my external HDD plugged in to my laptop forever! I needed to take the laptop away so unplugged the drive - and then tried to plug it in later and open the catalogue again to view the images. Seems like a very basic think to need to do? When I ejected my NAS this never happened - lightroom would just relocate the images again when the NAS was present.



The way you described it was that you removed the disk *while Lightroom was still running*. That is something you shouldn't do, or else you will get the 'missing images' signs (for obvious reasons). Those exclamation marks aren't a big deal, as long as you know why they are there, but you mentioned this as a 'new problem'. If you remount the disk and then start Lightroom again, the 'missing images' signs should be gone again. If you keep Lightroom running (with the laptop in sleep mode) and connect the disk again after waking the computer from sleep, you may indeed notice that the signs do not disappear after the disk has mounted. I've seen that too a few times when I started Lightroom before my photo disk was fully mounted. Again, no big deal, just an interface glitch. Restart Lightroom and the problem should be gone.


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## Sean Michael (Aug 1, 2016)

Hi Johan - thanks for your help. Yep i had already tried restarting Lightroom and re-plugging in hdd disk, but that hadn't got rid of the problem. However i tried plugging the disk in first and then restarting today and that did the trick! Is there a safe way to eject the ext HDD disk within lightroom for removal or does than not matter? 

Final thought- I decided to keep all my images in Lightroom, and not use the NAS directly for images as its to slow for browsing my images even when hard wired via Gigabit ethernet. Many previews were taking forever to appear and lots of chronic lagging when scrolling over these blank previews waiting for them to appear (many never did). It all definitely a lot quicker now I'm using external hdd and updated Lightroom to cc.  

I'm going with external HDD backed up to NAS. I am still getting problems thought with many previews in the library module staying blank for ages however not nearly as long as will the NAS.  Even with ext HDD many previews still do not build until i hover over them in the library module - no matter how long i leave the library open and wait for Lightroom to fill in all the gaps. Seems a bit lame. I will do further research into how these previews work and maybe create another post if necessary thanks everyone..


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## Johan Elzenga (Aug 1, 2016)

Just quit Lightroom first, then eject the disk. When you start up again, mount the disk first, then start Lightroom.

Lightroom does not rebuild previews which are 'out of sight' in the grid. It only starts rebuilding them when you scroll the grid so that the previews come in sight. This is annoying and lots of people complain about it, but it's the way it is. The only way to force rebuilding is to select all images and then choose 'Library -Previews - Build Standard-sized Previews'.

On import, Lightroom should build all previews no matter if the image is visible in the grid or not. However, if you quit Lightroom before it had the chance to build all of them, it won't continue building after you start it again. This may be what you are seeing.


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## Sean Michael (Aug 1, 2016)

Thanks! - it seems to need to rebuild the previews every time i restart lightroom though?...   ps. you seemed to contradict yourself there first saying "ightroom does not rebuild previews which are 'out of sight' in the grid" then saying "On import, Lightroom should build all previews no matter if the image is visible in the grid or not" - in the second state t are you referring to performing " Build Standard-sized Preview:?


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## Sean Michael (Aug 1, 2016)

ps. I think its was this building previews process that was slowing my NAS down to a grinding halt by the way (even when hardwired to Gb ethernet)... possibly because of bandwidth or just limited download speed affecting it as discussed earlier. Anyway I'm leaving that problem alone now!


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## Johan Elzenga (Aug 1, 2016)

Sean Michael said:


> Thanks! - it seems to need to rebuild the previews every time i restart lightroom though?...   ps. you seemed to contradict yourself there first saying "ightroom does not rebuild previews which are 'out of sight' in the grid" then saying "On import, Lightroom should build all previews no matter if the image is visible in the grid or not" - in the second state t are you referring to performing " Build Standard-sized Preview:?



No, I don't contradict myself. There is a difference between *building* the previews on import, and *rebuilding* them when you've made changes. When you import new images, Lightroom will *build* previews for all of them (providing that you selected that in the import dialog). But when you select say 100 images in the grid and apply a develop preset on them, Lightroom will only *rebuild* the previews of those images are are visible in the grid. It will not rebuild the previews of images that are invisible, until you make these visible by scrolling the grid. You can force Lightroom to rebuild all 100 previews by using that menu (even though the menu says 'build', not 'rebuild').


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## Sean Michael (Aug 1, 2016)

Ok thanks - in my case though I have not made  any edits and it seems to be building preview every time I reload  the database.  il try the rebuild option as see what happens!


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## Sean Michael (Jul 30, 2016)

I'm trying to using a nas to store the Lightroom image library but it is super duper slow! I have a very fast synology nas ds716+ , a super fast  Mac book pro 2015, and bt home hub 5. I have gigabit Ethernet via fiber optic cable. Even when it's all connected wired, nas to router , Mac to router using gigabit Ethernet pluged in into macs thunderbolt port, it's still very slow taking forever to load up all the previews on even a single folder of 50 images.o to half the images will just stay greyed out until you click to open them individually- then you can see them and work on them . Doesn't seem to be a viable option ? Not sure why people Are endorsing it?


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## Johan Elzenga (Aug 1, 2016)

Sean Michael said:


> Ok thanks - in my case though I have not made  any edits and it seems to be building preview every time I reload  the database.  il try the rebuild option as see what happens!



It probably means that Lightroom wasn't finished yet. Force rebuild should solve that.


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