Pfsense on hdd or flash memory?



  • I'm about to buy a shuttle pc to use with pfsense but I'm wondering what storage to use.
    Is it best to use the internal hdd or a flash cart?



  • If you plan on installing packages, use a hard disk.



  • Has the advent of SLC compact flash changed the situation a little bit?  I'm thinking our next box will be either SLC SSD or SLC CF.  Many have said there are no write limitations on these new style cards.



  • There are still write limitations, they're just higher with professional level units.



  • With modern wear-leveling algorithms you "should" not hit the write-limitation.

    Assume a disk of 4 GB.
    If you write constantly with 50 MB/s to the disk you would write every ~80 seconds to the same cell.
    4096/50 = 81.92
    Assume conservatively that you can write 100'000 times to a single cell on an expensive card (some claim to be able to write 1'000'000 times)
    100'000 * 80s = 8'000'000s
    8'000'000s / 60 = 133'333.3 min
    133'333.3 min / 60 = 2222'.2 hours
    2222.2 hours /24 = 92.6 day

    So if you write constantly with the maximum speed to a disk with a conservative assumption of maximum 100'000 writecycles the card would start to show first signs of failure after 93 days.

    Of course if you take a 16 GB card (*4),
    "only" 10 MB/s (*5, still a lot of disk traffic…)
    and 1'000'000 writecycles (10)
    you have 93 days 105
    4 =18518 day
    18518 / 365 = 50.7 years.

    But the more expensive cards are about the same price as a harddisk ;)


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