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I have a Lenovo U410 with a 1TB HDD (ST1000LM024 HN-M101MBB) and a cache SSD (SanDisk SSD U100 24GB). I want to install Ubuntu 14.04 as the only operating system. I'm currently looking into the right way to use and partition the two drives.

I'm currently using a dual-boot system with Windows 8 where the Ubuntu partition uses 16GB on the HDD for the installation and has a different drive in common with Windows 8 for the home folder. I have found this 16GB to be on the limit since I have a lot of software installed. I therefore don't want to use the SSD for Ubuntu and have only the home folder on the HDD: just to be sure I won't run out of memory.

Now what are my options?

  • Everything on HDD but home on SSD, as suggested here? I could have large files in a data partition of the hard disk, but configuration files of /home on the SSD.
  • The operating system on SSD, but /swap, /usr and /home on HDD, as suggested here?
  • Perhaps only have the system use the SSD to boot fast (if that's possible?)?
  • Other options...?

And then there is this post which says I shouldn't trust a cache SSD as it's not intended to be reliable. Is that true? Is there a way to check if my cache SSD is suitable to run the OS or hold the home folder?

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  • What do you want to be quickest? Accessing file in the home, opening programs, boot time ... Do you what manufacturer made the SSD? – Wilf Mar 14 '15 at 16:20
  • @Wilf thanks for your answer. It's a SanDisk SSD U100, is that an answer to your question? I think I would prioritize on boot time, then opening programs, then accessing files in the home. But doesn't opening programs also depend on config in the home folder? –  Mar 14 '15 at 16:38
  • yeah it does :) Putting / on the SSD (if it works) should mean it boots and loads programs quicker - though config files and the files you may want to load will be in /home, there is often not as much to load (e.g. 3Mb of config files compared to 60Mb of program (depends on what it is as some gaming ones (steam urbanterror etc) 'install' in the home directory). The problem is that there might not be a definitive answer as this can vary from case to case and answer are often opinionated.... Have you tried using the SSD for cache and seeing if it made a difference? – Wilf Mar 14 '15 at 17:00
  • @Wilf I see, then I will try to do that. Three questions still though :) 1. The story that a cache SSD wouldn't be reliable enough, is that true? Is there a way to test if my SSD drive is reliable enough? 2. If I would run out of space on the SSD and I need to install more programs, I presume it's possible to move /usr to the HDD? 3. So on installation I would give / to the SSD, and /home, /swap and /tmp to separate partitions on the HDD? - Since, as you say, there is no definitive answer, perhaps you could write an answer explaining the different trade-offs? That could be useful for others :) –  Mar 14 '15 at 17:07
  • How would I try to use the SSD for cache? –  Mar 14 '15 at 17:07
  • like using it as swap space? – Mateo Mar 16 '15 at 19:27
  • If you have 4GB or more of RAM you may never use swap. Is your Ubuntu install so large as you are including /home as /home cannot be the shared NTFS data partition. Then you do start to get more data in / when it is both. My / is 11 GB including /home, but all data folders and some hidden folders in /home that have lots of data are in my data partition and linked back to /home. My /home is about 2GB of the 11GB only because of .wine for Picasa. – oldfred Mar 16 '15 at 20:48
  • I do have a suggestion on what you can look into. If I recall correctly, SSDs are unreliable because they only have a limited amount of reads and writes into the corresponding blocks and such. So, if you can look into finding a program that monitors the health of the SSD, then you can just use that on a frequent basis to determine when it might break, and then just backup to your HDD before it does. This might minimize the risk of data loss, thus taking reliability off the table. I d – Shane Kelly Mar 16 '15 at 20:07

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Since I wanted to focus on fast booting and starting programs, I decided to try the following:

SSD: OS installation, /usr and /opt for programs
HDD: /swap, /var, /home

I decided to have /var on the HDD as well because I have rather big databases in the /var/lib/mysql and also my /var/www is quite spacious.

So far this is working fine. Booting and starting programs is incredibly fast. If I experience any problems with the SSD in the future I will update this post. So your safest bet is to have a look at the timestamp: if this post is old enough and I didn't edit it, you can assume I didn't have any problems.