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  1. #1
    Join Date
    Feb 2005
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    41

    Raid but no hot-swap .. minimizing downtime...

    Hi,

    I just need you guys to verify this.

    I read a lot of advantages of Raid disks, however after talking to my current hosting provider, he told me that even if I use raid-10 disks, downtime is inevitable in the event of a replacement for a spoilt hard disk if the server is not on a hot-swap mount (as the technicians need to turn off the server during the changing of disks)

    This makes me think that hot-swap with raid is really a MUST if I wish to maintain the highest level of uptime for my server.

    I ask this because I don't see this being discussed often. I only notice many discussions about the differences of Raid levels, whereas if uptime is important for a business, a hot-swap rackmount is equally important.

    Is this true?

    Thanks.

  2. #2
    Join Date
    Nov 2005
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    352
    Yes. With hotswap there is no downtime when changing out a failed drive. In many cases you don't even have to reboot nor log in to the server since many RAID controllers will automatically begin rebuilding the RAID array as soon as it detects that a replacement drive has been added to the system.

  3. #3
    Join Date
    Oct 2008
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    2,249
    If you really need 100% uptime and dont mind spending the extra cash then yes hot-swap is great in terms of helping to that goal. Like the post before me said the raid card should read the hd and go back to normal in a day or 2 depending on how much files need to be moved.
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  4. #4
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    Feb 2005
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    Well in that case I don't see much difference between getting a raid-1, raid-5 or raid-10 on a company which doesn't offer hot-swaps other than the difference in speed and performance.

    I am more particular about maintaining uptime for my server. With that in mind, even getting raid-10 disks will result in downtime in the event of a hard disk replacement.
    Last edited by citrine; 09-25-2009 at 07:20 PM.

  5. #5
    Join Date
    Feb 2005
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    41
    Quote Originally Posted by darkeden View Post
    If you really need 100% uptime and dont mind spending the extra cash then yes hot-swap is great in terms of helping to that goal. Like the post before me said the raid card should read the hd and go back to normal in a day or 2 depending on how much files need to be moved.
    There are a few companies which offer it without additional charge - Softlayer on all raid servers except raptor drives. (just chatted with their sales rep today)

    - Wiredtree on all Dual Xeon servers standard, as well as on Dual Core and Quad Core servers with 3 or more disks. (or else it's only additional $20/mth)

    Sadly, I was quoted additional $150/mth from LiquidWeb for hot-swap rack.. :-( :-(

  6. #6
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    Oct 2008
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    Quote Originally Posted by citrine View Post
    There are a few companies which offer it without additional charge - Softlayer on all raid servers except raptor drives. (just chatted with their sales rep today)

    - Wiredtree on all Dual Xeon servers standard, as well as on Dual Core and Quad Core servers with 3 or more disks. (or else it's only additional $20/mth)

    Sadly, I was quoted additional $150/mth from LiquidWeb for hot-swap rack.. :-( :-(
    Id say go with softlayer for the best network uptime and wiredtree for the best management..... Liquidweb was nice when I used them but some of there items are expensive when they shouldnt be.
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  7. #7
    Join Date
    Mar 2009
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    Quote Originally Posted by citrine View Post
    Well in that case I don't see much difference between getting a raid-1, raid-5 or raid-10 on a company which doesn't offer hot-swaps other than the difference in speed and performance.

    I am more particular about maintaining uptime for my server. With that in mind, even getting raid-10 disks will result in downtime in the event of a hard disk replacement.
    In theory, you should expect more disk failures with RAID 1 or RAID 10 than RAID 5.

    The reason is that RAID 1 and RAID 10 need more disks than RAID 5 to store the same amount of data, and so will experiemce more disk failures.

    Suppose that disks fail on average once every hundred years; and suppose you need to store 600 disks'-worth of data.

    With RAID 1 or RAID 10, you will need 1200 disks, and so can expect 12 disk failures a year.

    With RAID 5 using 7-disk arrays, you will need 700 disks, and so can expect 7 disk failures a year.

  8. #8
    Join Date
    Nov 2003
    Location
    Lynnwood, WA
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    438
    Quote Originally Posted by tim2718281 View Post
    In theory, you should expect more disk failures with RAID 1 or RAID 10 than RAID 5.

    The reason is that RAID 1 and RAID 10 need more disks than RAID 5 to store the same amount of data, and so will experiemce more disk failures.

    Suppose that disks fail on average once every hundred years; and suppose you need to store 600 disks'-worth of data.

    With RAID 1 or RAID 10, you will need 1200 disks, and so can expect 12 disk failures a year.

    With RAID 5 using 7-disk arrays, you will need 700 disks, and so can expect 7 disk failures a year.
    Please stop. Just stop. There are so many inaccuracies, half-truths and flat out lies in the above post that I urge anyone reading it to purge it from their mind before you act on any of it.

    Please do not take advice on RAID from someone who thinks a 1200-disk RAID1 has any higher capacity than 1 disk. It doesn't. It's just the most redundant data in history.

    As for RAID5 being 'safer' than RAID10 because it 'needs less disks'.. wow. That logic barely makes sense on paper; if you've ever had to DEAL with a ton of RAID arrays in production environments, you'd realize that there's a dozen other reasons why the higher-disk-count RAID10 is generally far safer for your data than RAID5, not to mention faster as well.

  9. #9
    Join Date
    Aug 2004
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    Canada
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    Quote Originally Posted by citrine View Post
    There are a few companies which offer it without additional charge - Softlayer on all raid servers except raptor drives. (just chatted with their sales rep today)
    Systems with raptor drives are hot swap capable as well. Whether you use standard SATA, Raptor SATA or SAS they all use the same chassis. Thus they're all hot swap capable. Not sure why the sales person said otherwise. I can speak from experience we've had to replace raptor drives they can be hot swapped.
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  10. #10
    Join Date
    Sep 2003
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    Quote Originally Posted by citrine View Post
    I read a lot of advantages of Raid disks, however after talking to my current hosting provider, he told me that even if I use raid-10 disks, downtime is inevitable in the event of a replacement for a spoilt hard disk if the server is not on a hot-swap mount (as the technicians need to turn off the server during the changing of disks)
    If they are RAID w/o hot-swap capabilities it's reasonable to expect they explain this in the TOS, etc and clearly. My provider offers RAID servers both hot-swap and not hot-swap. For the non hot-swap they clearly let you know in the agreement about 15 minutes downtime is required to changed a failed drive in those servers. Perhaps if one drive is detected to have failed they let you know and you can request the time for the tech. to replace it. Then it would be nice if they accept your request to do this when your server is experiencing the least amount of traffic.

  11. #11
    Join Date
    Mar 2009
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    2,218
    Quote Originally Posted by Nex7 View Post
    Please stop. Just stop. There are so many inaccuracies, half-truths and flat out lies in the above post that I urge anyone reading it to purge it from their mind before you act on any of it.

    Please do not take advice on RAID from someone who thinks a 1200-disk RAID1 has any higher capacity than 1 disk. It doesn't. It's just the most redundant data in history.

    As for RAID5 being 'safer' than RAID10 because it 'needs less disks'.. wow. That logic barely makes sense on paper; if you've ever had to DEAL with a ton of RAID arrays in production environments, you'd realize that there's a dozen other reasons why the higher-disk-count RAID10 is generally far safer for your data than RAID5, not to mention faster as well.
    Suppose you need to store 600 disks' worth of data.

    And suppose you decide you are going to use RAID 1.

    How many disks will you need?

  12. #12
    Join Date
    Feb 2007
    Location
    Florida
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    Hot swap is nice for minimal downtime but running a RAID without hot swap still reduces your downtime greatly compared to not running RAID at all. Downtime from failed disk > Downtime from swapping out failed RAID disk.
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  13. #13
    Join Date
    Sep 2009
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    Geffen (NL)
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    Yes. With hotswap there is no downtime when changing out a failed drive idd. You can switch the disk without downtime!

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