DragonFly BSD
DragonFly users List (threaded) for 2011-12
[Date Prev][Date Next]  [Thread Prev][Thread Next]  [Date Index][Thread Index]

Re: Which is ideal with HAMMER? softraid or hammer volume_add

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Tue, 27 Dec 2011 09:20:05 -0800 (PST)

    Definitely not hammer volume add, that's too experimental. Soft-raid
    is a bit of a joke in my view, since it typically ties you to a
    particular motherboard and bios (making it difficult to physically
    move disks to another machine if the mobo or psu dies), and as with
    all soft-raid systems any sort of power failure during a write is
    likely to cause unrecoverable data loss.  Honestly I don't know of a
    single system that ever had fewer failures with soft-raid than with
    single disks w/ near real-time backup streams.

    For HAMMER1 the best set-up is either a real raid system or no raid
    at all and a master/slave server setup, depending on what is being
    served.  Unfortunately nothing in BSD really approaches Linux's block
    level clustering and VZ container system at the moment (which is a bit of
    a joke too when it comes to multiple failover events but works pretty
    well otherwise).

    If you have a small system then there's no point running RAID.  If you
    have a larger system then there's no point running a single server.
    And running RAID on multiple servers eats a lot of power so for storage
    needs less than what conveniently fits on one or two disks there's no
    point running RAID at all... you run redundant servers instead and use
    a SSD as a caching layer in front of the slower hard drive.

    For larger single-volume storage needs multiple real raid system for
    primary and backup with all the insundry fallback hardware is the only
    way to go.  Soft-raid won't cut it.

					Matthew Dillon 

[Date Prev][Date Next]  [Thread Prev][Thread Next]  [Date Index][Thread Index]