researching a "growable" long-term storage solution

Discussion in 'Storage' started by Mikhail Teterin, Apr 6, 2004.

  1. Hello!

    I'm thinking of putting my various CDs, DVDs, digital pictures, backups,
    etc. on a large array of disks. Performance is secondary to reliability
    and the software or hardware RAID5 will do.

    There are two issues, however, which most common RAID5 setups don't seem
    to address without recreating the whole array:

    1. replacing a failed disk with a bigger one
    2. adding a disk

    The first item seems more important. If I build a 6-disk array from 200Gb
    units, I'll be comfortable for the next several years (one hopes). During
    this time, at least one disk might fail, but the most cost efficient disk
    will then, likely be much bigger. Is there a RAID solution today (not a
    RAID5 necessarily, but still with a tolerance for the loss of at least one
    drive), that will be able to make use of the additional capacity of the
    replacement?

    Likewise for the second item -- if I decide to "grow sideways", by adding a
    drive (of the same or bigger capacity)... Is there a RAID solution, that
    will be able to grow like that?

    Obviously, I don't want to recreate the filesystem in either case, but
    simply use growfs(8)? And I don't want the total capacity to be less than
    the sum of all drives minus the size of the biggest one of them...

    The server will run FreeBSD, although some other Unix-like OS is a
    possibility...

    Thanks for any ideas!

    -mi
     
    Mikhail Teterin, Apr 6, 2004
    #1
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  2. Mikhail Teterin

    ZedGama3 Guest

    ZedGama3, Apr 7, 2004
    #2
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  3. Mikhail Teterin

    Zak Guest

    Linux uses partitions as components of RAID devices. If you replace more
    than a single disk, you could use the 'leftovers' as new partitions in a
    new RAID, which you could concatenate to the existing raid5 if you liked.
    People do it, but it seems risky, as the code will not be sufficiently
    tested.


    Thomas
     
    Zak, Apr 7, 2004
    #3
  4. Mikhail Teterin

    Ean Kingston Guest

    Software RAID works at the slice/partition level so you can make much more
    efficient use of different sized disks. This will allow you to replace
    smaller disks with bigger ones.

    Raid 0+1 (striping and mirroring) will allow you to grow your filesystem by
    adding more disks. It will also give you redundancy in case of the loss of
    one disk. The only down side is you have to buy twice as many disks as
    space you need. So, 6 200GB disks would yield 600GB this way (it would
    yield 1TB in RAID5).
     
    Ean Kingston, Apr 7, 2004
    #4
  5. ZedGama3 wrote in <[email protected]_s52>:

    =I believe your looking for vinum.
    =http://www.freebsd.org/cgi/man.cgi?query=vinum

    =I've not used it personally but the man page seems to suggest
    =that you can add / remove drives from the array with minimal hassle.

    I'm pretty sure, I'll have to recreate the filesystem afterwards :\

    Which is against my (self-imposed) requirements...

    -mi
     
    Mikhail Teterin, Apr 7, 2004
    #5
  6. Do they cater to consumers (mere mortals)? Does not seem so from their
    web-site...

    -mi
     
    Mikhail Teterin, Apr 7, 2004
    #6
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