3 ssd disk array, what raid level can I use?

Discussion in 'Questions and Answers' started by Darwin, Oct 24, 2014.

  1. Darwin

    Darwin Member

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    Dec 19, 2013
    I am a software guy, not hardware one. Please forgive me if my question sounds stupid :)


    I'm thinking about renting one of those 3xssd soyoustart servers, but what I know about raid can be resumed in: raid1, 10 and that 5 is a no no for ssd.


    That said and looking for data integrity, what raid options can I use in that server? Why that raid level x you recommend is the best one? I don't need mb/s neither iops porn, what ssds give by default is good enough for me.


    I am looking for a soyoustart server with hardware raid, but don't mind to use soft raid if that is the best option.


    Almost forgot, I plan to slice that server in a few KVMs (maybe 3-6 vms)
     
  2. rds100

    rds100 New Member Verified Provider

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    How much space do you need? If not more than the size of a single SSD, i would do a RAID1 with two SSDs and then use the third to locally store backups. Of course make remote backups too.
     
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  3. HalfEatenPie

    HalfEatenPie The Irrational One Retired Staff

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    HalfEatenPie
    This is probably the best response in my opinion.  

    Three is such an awkward number.  
     
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  4. lowesthost

    lowesthost Member Verified Provider

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    Raid 1 and the 3rd drive as a hot spare
     
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  5. William

    William pr0 Verified Provider

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    RAID5 will work in SW but is not recommended for SSDs.

    I personally would build a ZFS Z1.
     
    Last edited by a moderator: Oct 24, 2014
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  6. Darwin

    Darwin Member

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    I was aiming at least 200 gb, but can live with 120gb with raid 1.


    So md raid 10 or 1e are just plain weird and sucks?

    Thanks, going to research a bit about ZFS Z1.
     
  7. Vijay

    Vijay New Member

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    There is a way to do a triple disk mirror with ZFS . This way you would keep the 3 disks in the pool... and survive 2 disk failures.. This is better than HS solution. since with HS, if during rebuild there is a failure, you would loose the data.

    Also, you could create a pool with all 3 disks, and create a dataset with 'copies'=3 attribute.. That is that dataset (FS) and only that dataset has 3 copies. Depending on the space that particular dataset will be copied to 3 different disks in pool... Hence, for non-critical data, you can save space do keeping copies=1. I haven't done this myself, so I do not fully understand the data protection implications...

    Check this link.. https://blogs.oracle.com/relling/entry/zfs_copies_and_data_protection

    PS: all of the above are based on my experiences with Solaris & FreeBSD.. Not sure about Linux..
     
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  8. raj

    raj Active Member

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    Last edited by a moderator: Oct 24, 2014
  9. willie

    willie Active Member

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    RAID 1 on two of the drives containing your live data.  System and temporary stuff and static files on the third drive: reinstall if it crashes.  SYS comes with 100GB of free ftp storage space, so use that to backup the non-mirrored drive.  Or if you're not running live databases, then just run without RAID and have a cron job doing rsync backups to another server (or to the ftp area) every few hours. 
     
  10. Flapadar

    Flapadar Member Verified Provider

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    Why bother? Unless he's needing 3 drives worth of data that's just wasting peace of mind.

    +1 for RAID1 with hot spare.
     
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  11. Darwin

    Darwin Member

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    Sorry to bump my old thread, but I did a few experiments and I will answer my own question about md raid 10 with 3 disks:

    md raid 10 with 3 disk is meh. Didn't see any advantages, other than 50% more space than a 2 disk raid 1 (which I don't need). But speed wasn't great and only 1 disk can fail before the raid blows. (to add some context, I did that experiment using an old server using HDDs, not SSDs)

    Thanks to everyone who suggested Raid 1 + a hot spare disk. This sounds the best option to what I need.
     
    Last edited by a moderator: Oct 29, 2014
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  12. sshgroup

    sshgroup New Member

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    Nov 3, 2014
    you can use raid 5 but  raid 10 & one other disk better always
     
  13. Clouvider-Dom

    Clouvider-Dom Member Verified Provider

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    Depending on the amount of space you need I would recommend upgrading to 4th drive and going for RAID10.

    If 1x SSD size space is enough I would recommend going for RAID1. RAID5 is not recommended for SSDs due to large number of write cycles that may significantly shorten your SSD lifespan. 
     
  14. willie

    willie Active Member

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    This is about SoYouStart, which has fixed configuraitons.  It's not possible to add a 4th drive to the 3 drive systems.