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Thread: Please share experience with SD card 'drive' use in Linux

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    Default Please share experience with SD card 'drive' use in Linux

    I'm still 6 to 18 months away from purchasing a new laptop, but before I do I am keen to learn whether it is worth purchasing an SD card 'drive' for Linux in the laptop. Indeed I could also consider the use of such an SD device on a desktop PC ....

    What are the experiences of our openSUSE users ? any tidbits to offer ? any hints our users have ? ... or simply are there any pieces of basic information to put forward that those of us who don't have such a device would never consider ?

    I noted an article here: How to tweak Linux to run reliably on flash memory? - Unix and Linux - Stack Exchange about tweaking linux for using such SD card devices in place of one's hard drive.

    Suggestions such as placing /var , /home on a separate internal hard drive (or even on an external drive) were proposed. Another suggested putting /tmp on an internal (or external) drive, or even finding a way to mount /tmp into RAM. The reason being is there are a limited number of erase-cycles/writes for an SD card, so the intention is to maximum the SD card life by putting writes for some directories to a different device.

    Plus for ext3 I noted this sugestion:
    Under ext3, the journal is the most frequently written file, and those writes will eventually fill a block, forcing the erase of another block. Setting a larger commit= value on mount would gather these journal writes into larger chunks.


    Finally, to echo other solutions, mounting with noatime is a standard practice that will reduce impact.
    Which of our users use such a device and what can you recommend ?

    I recall there was at least one previous thread on this subject where some of our users posted some information, but I can't find that thread !

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    Default Re: Please share experience with SD card 'drive' use in Linux

    In hindsight, my title and my terminology was both poor and misleading. I should have stated "SSD" or Solid State Disk so as to avoid confusion.

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    Default Re: Please share experience with SD card 'drive' use in Linux

    Once I managed to get my terminology correct (ie SSD / Solid State Disk) I obtained a LOT more useful information from Google:

    For example: Geek Sheet: A Tweaker's Guide to Solid State Drives (SSDs) and Linux | ZDNet where they have various recommendations such as
    • if your system motherboard uses a disk caching bus, change the BIOS setting from “Write Through” to “Write Back”. "
    • use the “noop” simple I/O scheduler instead of the "elevator" scheduler
    • change the file system mount options on SSDs to “noatime” and mount your /tmp in RAM.
    • Ditch the journal and RAID your SSDs ... although they later qualified that, noting that formatting the filesystem as ext4 and mounting with the journal enabled and RAID1 may actually be faster than ext2 RAID1 and provide additional referential integrity, and mounting a ext4 RAID1 in unjournalized mode may also be faster than ext2 RAID1. They also noted concerns were raised about what could happen if the power goes out and you lose referential integrity of the FS and are unable to replay it from the journal -- so you might want to use a traditional disk using a journaled FS to sync the database to for backups.


    and for example here: Open Technology: Linux SSD Optimization Guide
    • they recommend a non-journaling filesystem (ext2) which is a bit in contrast to above
    • they recommend moving part of /var and /tmp into ram (and they show the fstab edits needed to do so) and the script needed to repopulate the ram ...
    • they recommend tuning in the kernel the disk write scheduler (or elevator) from the default deadline to noop
    • they recommend changing the caching method from the write-through caching method to write-back (if write-back is supported by the SSD device).


    It makes me think an openFate feature may be for the openSUSE installer to detect if an SSD device is in use and intended to be used for / and then have the openSUSE install automatically apply the more conservative of the various tweaks. But thats speculation of somone who has no such device, so that has to be considered speculative at best.

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    Default Re: Please share experience with SD card 'drive' use in Linux

    While it's a good idea to reduce unnecessary writes in any case, it's not because you will wear out any particular spot. SSD drives these days incorporate wear leveling which will transparently spread the writes across the device.

    IMO, wait 5 to 17 months before you look at the situation again. Technology is changing so fast.

    Personally I'm contemplating a SSD for the system FS on my next desktop, but there will be a lot of techno jumps there anyway: SSD, SATA-3, USB-3, HDMI, BluRay, some low power CPU, so I'm not going to spend time on planning until later.

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    Default Re: Please share experience with SD card 'drive' use in Linux

    Quote Originally Posted by ken_yap View Post
    IMO, wait 5 to 17 months before you look at the situation again. Technology is changing so fast.
    Indeed my plan is to delay my purchase anywhere from 6 months (for my wife) to 18 months (for me). But I may need to track the technology (under Linux) a bit more, as typically I need more than a month to bring myself up to speed technically before a purchase. Also, if there are specific applications/driver/kernel tuning/optimisation needed (which I have no clue about) then I like to vote for the appropriate openFate submission LONG before my purchase date so as to attempt to assist in the motivation to have appropriate apps/drivers in place for when I purchase. Sort of an extended self interest.

    Quote Originally Posted by ken_yap View Post
    Personally I'm contemplating a SSD for the system FS on my next desktop, but there will be a lot of techno jumps there anyway: SSD, SATA-3, USB-3, HDMI, BluRay, some low power CPU, so I'm not going to spend time on planning until later.
    I am also considering same (add an SSD for my current desktop).

    For any replacement desktop I agree re: SSD, USB-3. I confess I have not read up on SATA-3. I think HDMI is mostly already here (all our new PCs in our apartment have this now). Reference BluRay - does it have a chance of making market inroads ? ...

    Currently though, SSD is what interests me the most, ... more than any of the other features. SSD drives are available now at our local store (albeit they are incredibly expensive).

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    Default Re: Please share experience with SD card 'drive' use in Linux

    BluRay is already entrenched because of the entertainment market, so by the time I buy there shouldn't be much premium for a BluRay burner. It may be a while before I actually need to burn a BluRay disc. In the meantime it's useful to be able to watch movies in that format. One of my plans is to integrate the desktop better with the rest of the entertainment equipment. So the old KVM switch has to go as well as the LCD monitor and HDMI to the TV/monitor will replace them.

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    Default Re: Please share experience with SD card 'drive' use in Linux

    Quote Originally Posted by oldcpu View Post
    SSD drives are available now at our local store (albeit they are incredibly expensive).
    This is the sole reason I have not tried them. The performance jump is meant to be incredible and on your core I7 pc you should really notice a performance boost. If you have the money to afford one I would.. I'd probably only put the root system on there. Wouldn't put /home or /tmp on there due to the increased writing. But this is all theory since I don't have the money to spend on that. Want a new mobo, cpu, RAM, graphics card combo first! Can't play my games at my new monitors full hd resolution!
    "To err is human... to really foul up requires the root password."

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    Default Re: Please share experience with SD card 'drive' use in Linux

    Quote Originally Posted by oldcpu View Post
    I recall there was at least one previous thread on this subject where some of our users posted some information, but I can't find that thread !
    I finally had one of these threads pointed out to me: Using a SSD Hard Drive with openSUSE and the TRIM Command

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    Default Re: Please share experience with SD card 'drive' use in Linux

    For the amount of issues i have heard about using SSD's in linux I never had one issue with using one on Ubuntu on my mothers laptop.
    Guess I am lucky.

    Please note: this is not a suggestion that Ubuntu is better for use of SSD's, I just happen to have installed ubuntu on my moms computer, she uses a camera with a SSD in it that seems not to work too well under Ubuntu via USB (the connectivity seems flaky, we did check the USB cord and it seems not to be the issue. I personally suspect the USB port on the camera is to blame) but we are still able to work out the drive thanks to her SSD port.
    Though oddly enough the opposite problem seems true under windows 7, the SSD card seems not to work too well under windows 7 and the USB seems fine, its a very weird camera issue indeed.

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    Smile Re: Please share experience with SD card 'drive' use in Linux

    So, the primary difference between using a SSD drive and say a fast hard drive I see is the startup speed of openSUSE. It is the most dramatic difference one can measure. Since I am only using the SSD I have as the main / drive and not for /home, perhaps other advantages might exist I can not see. Startup speed for me shows that a standard, but fast PC can load openSUSE from the Grub menu, including a fast enter of your password, to the loading of your selected desktop in about 50 seconds. A similar setup with a SSD drive can reach the same point in about 25 seconds, or half the time. Obviously if you perform any other tasks that use your SSD drive, they will also be sped up if they require frequent reads and writes from your drive. I have ran into a few here that claim 30 second startups without an SSD. I would expect a considerable reduction in number of kernel modules being loaded would need to be done to speed up a standard hard drive to equal a SSD, but that is only my opinion.

    Thank You,
    My Blog: https://forums.opensuse.org/blogs/jdmcdaniel3/

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    Its James again from Austin, Texas

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