Results 1 to 13 of 13

Thread: NAS Raid Guidance Please

  1. #1
    Syd
    Syd is offline
    Hanging on the Edge Syd's Avatar
    Join Date
    Jan 2006
    Location
    Kent
    Posts
    1,636
    Thanks
    69
    Thanked
    32 times in 29 posts
    • Syd's system
      • Motherboard:
      • EVGA 760 Classified / MSI P35 / gigabyte gaming 7 1150
      • CPU:
      • I7 920@3.8 / E8400 / 4790k
      • Memory:
      • 18GB Dominator DDR3 1600 / 4GB / 16GB GSill
      • Storage:
      • 2 x Samsung 830 256/ 120GB Vertex 2 / Sam840's/ Sam SM951
      • Graphics card(s):
      • 690GTX on Water/IGP/ 980ti
      • PSU:
      • AX860/1250w Seasonic
      • Case:
      • TJ07 / PCV700
      • Operating System:
      • 7 64/ 10 64
      • Monitor(s):
      • NEC 3090 + Dell 2405PW
      • Internet:
      • Sky Fibre

    NAS Raid Guidance Please

    Morning to you all

    Prompted by reading a review of Nas boxes this month in Custom PC, I have come to realise that it really is about time that I buy myself some sort of network available storage and backup system.
    So I am thinking one of the NAS boxes with a pair of 1.5TB drives in Raid Mirror will give me both those functions............

    Only thing is I have read before that raid mirror DOES NOT provide a foolproof backup function - but in the review It states that it does, hence my confusion!!

    I basically have about 150GB of photos 500GB of music and 50GB of archived nonsense that I would like to protect. So if I did what I was thinking would I be protecting myself and allowing access printer, memory stick to both machines as an extra benefit??

    Thanks
    Syd





    My very first watercooled PC project log

  2. #2
    Welcome to stampytown! Salazaar's Avatar
    Join Date
    Dec 2004
    Location
    Oxford
    Posts
    4,435
    Thanks
    505
    Thanked
    351 times in 252 posts

    Re: NAS Raid Guidance Please

    Mirroring provides a backup in case one drive fails, in which case you replace the drive and rebuild the array.

    However, if your NAS box fails you have no external backup and you either lose the data or hope that you can rebuild or extract it somehow.

    And IMHO, Custom PC has been going down the tube for some time now.
    ____
    (='.'=)
    (")_(")

  3. Received thanks from:

    Syd (06-08-2010)

  4. #3
    Super Nerd
    Join Date
    Jul 2008
    Location
    Cambridge
    Posts
    1,785
    Thanks
    22
    Thanked
    105 times in 72 posts

    Re: NAS Raid Guidance Please

    RAID 0 = Striping, result is higher performance on read and write but NO redundancy, double the risk of data loss. Use only where the data is transient/temporary and performance matters most.

    RAID 1 = Mirror, redundant because if one fails you have another copy. Performance is usually similar to a single drive although some fancy controllers can increase read speed by using both drives. Rebuild is a simple copy, can be time consuming and data is vulnerable during the process. Not the most economical as usable capacity is 1/n but only requires 2 drives for redundancy.

    RAID 5 = Striping with distributed parity blocks. Read speed increases but writes are generally worse, a drive failure will reduce performance. Redundant because data can be reconstructed using the parity blocks, time consuming and processor intensive to calculate. Data is vulnerable during the rebuild. Economical as usable capacity is 1-1/n but requires minimum 3 drives.

    RAID 6 = Striping with double parity blocks. Same as RAID 5 but using double parity and can tolerate 2 drive failures before data is lost. Data is not vulnerable during the rebuild of first failed disc. Not so economical as usable capacity is 1-2/n and requires minimum 4 drives, economy increases the larger the array though.

    RAID 10 = A stripe of mirrors. Fast like a RAID 0, redundant like a RAID 1. Often used in high transaction environments like databases, common in the datacentre. Can tolerate a drive failure in each mirror set.

    ---

    RAID 6 is the safest, but I'd recommend 1 or 5 for home use. It's unlikely in a small array 2 drives will fail at the same time.

    Don't trust a RAID to protect your data though, if the NAS fails or is destroyed by fire/theft/electric surge etc then you'll lose the data too. Offsite backup should be used for anything that you really cannot afford to lose.

    RAID should be seen as a way to reduce the hassle of recovery from drive failure - i.e. you don't have to go to the backup and restore it.
    Last edited by kingpotnoodle; 06-08-2010 at 11:49 AM.

  5. Received thanks from:

    Syd (06-08-2010)

  6. #4
    Registered+
    Join Date
    May 2007
    Posts
    19
    Thanks
    0
    Thanked
    2 times in 2 posts

    Re: NAS Raid Guidance Please

    Quote Originally Posted by Syd View Post
    Only thing is I have read before that raid mirror DOES NOT provide a foolproof backup function - but in the review It states that it does, hence my confusion!!
    Raid 1 will keep an exact duplicate of your data on (in this case) two drives. If one drive fails you still have a copy of the data on the other disk.

    However if your data becomes corrupted - some of your photos refuse to open etc - the corruption will be mirrored on both drives.

    Remember that raid is not a backup

  7. Received thanks from:

    Syd (06-08-2010)

  8. #5
    Syd
    Syd is offline
    Hanging on the Edge Syd's Avatar
    Join Date
    Jan 2006
    Location
    Kent
    Posts
    1,636
    Thanks
    69
    Thanked
    32 times in 29 posts
    • Syd's system
      • Motherboard:
      • EVGA 760 Classified / MSI P35 / gigabyte gaming 7 1150
      • CPU:
      • I7 920@3.8 / E8400 / 4790k
      • Memory:
      • 18GB Dominator DDR3 1600 / 4GB / 16GB GSill
      • Storage:
      • 2 x Samsung 830 256/ 120GB Vertex 2 / Sam840's/ Sam SM951
      • Graphics card(s):
      • 690GTX on Water/IGP/ 980ti
      • PSU:
      • AX860/1250w Seasonic
      • Case:
      • TJ07 / PCV700
      • Operating System:
      • 7 64/ 10 64
      • Monitor(s):
      • NEC 3090 + Dell 2405PW
      • Internet:
      • Sky Fibre

    Re: NAS Raid Guidance Please

    Thanks for the responses

    However - now i'm still not sure what to do !!

    Could I set up a 2 disc nas box to have 1 drive as the data drive and the other to backup the data drive, ie not RAID ? And would that be a safer solution ?





    My very first watercooled PC project log

  9. #6
    Welcome to stampytown! Salazaar's Avatar
    Join Date
    Dec 2004
    Location
    Oxford
    Posts
    4,435
    Thanks
    505
    Thanked
    351 times in 252 posts

    Re: NAS Raid Guidance Please

    Quote Originally Posted by Syd View Post
    Could I set up a 2 disc nas box to have 1 drive as the data drive and the other to backup the data drive, ie not RAID ? And would that be a safer solution ?
    That's essentially what a mirrored raid array is. But it won't protect your data if the NAS hardware failed or was damaged in some way.

    To protect against that you'd need a full other set of hardware, preferably in an entirely different location, mirroring everything on your raid array.
    ____
    (='.'=)
    (")_(")

  10. #7
    Banned
    Join Date
    Jun 2008
    Posts
    2,129
    Thanks
    13
    Thanked
    189 times in 160 posts

    Re: NAS Raid Guidance Please

    Quote Originally Posted by babaracus View Post
    Raid 1 will keep an exact duplicate of your data on (in this case) two drives. If one drive fails you still have a copy of the data on the other disk.

    However if your data becomes corrupted - some of your photos refuse to open etc - the corruption will be mirrored on both drives.

    Remember that raid is not a backup
    Exactly... just to remind people..

    raid is not a backup


    The 'R' in raid is redundancy. Ie to keep service on failure, not backup.

  11. #8
    Senior Member watercooled's Avatar
    Join Date
    Jan 2009
    Posts
    10,858
    Thanks
    1,501
    Thanked
    935 times in 805 posts

    Re: NAS Raid Guidance Please

    Just in case you missed it RAID isn't about data integrity but availability and sometimes performance. Most home users however simply don't need that, despite most people accepting RAID as the norm for file servers/NAS boxes it's simply not necessary most of the time - JBOD or single disks is often the best choice for home users. Also note that rebuilding an array can be painfully slow, especially on the embedded hardware present in NAS boxes, usually taking much more time than restoring a backup. If the NAS itself is the backup then you could leave it at that, otherwise you'd be best backing up the NAS to either another NAS or depending on how much data is added to the NAS on a regular basis you could use USB HDDs to mirror the contents using rsync or something but that would depend on what's on it, if you need past archives etc.
    SNB has an interesting article about using RAID on NAS boxes: http://www.smallnetbuilder.com/nas/n...s-dont-do-raid
    This post is about WHS rather than NAS boxes but is still applies here and is really worth reading before you choose RAID over a backup: http://www.fearthecowboy.com/post/Wi...r-vs-RAID.aspx
    Also I agree about CustomPC, I bought this months article and lots of the articles seem very unprofessional and I noticed a few mistakes like this, they also seem to assume everyone overclocks the pants of their system and are very biased towards Intel. They also didn't bother including another good NAS choice in the alternatives bit - using a Linux distro with Samba, what I'm doing which cost less than most of the decent NASes in that review and beats even the fastest NAS on test at transfer speed (I get 70-90MB/s).
    Last edited by watercooled; 06-08-2010 at 02:26 PM.

  12. #9
    Admin team peterb's Avatar
    Join Date
    Aug 2005
    Location
    Southampton
    Posts
    19,339
    Thanks
    2,878
    Thanked
    3,387 times in 2,681 posts
    • peterb's system
      • Motherboard:
      • Nascom 2
      • CPU:
      • Z80B
      • Memory:
      • 48K 8 bit memory on separate card
      • Storage:
      • Audio cassette tape - home built 5.25" floppy drive
      • Graphics card(s):
      • text output (composite video)
      • PSU:
      • Home built
      • Case:
      • Home built
      • Operating System:
      • Nas-sys
      • Monitor(s):
      • 12" monocrome composite video input
      • Internet:
      • No networking capability on this machine

    Re: NAS Raid Guidance Please

    Hmm - seems my mantra "RAID is not a backup" is being widely adopted - which can only be a good thing!

    As others have said, RAID1 is about data resiliance and server up time as much as anything. With two drives, if one fails the other keeps on going until the faulty drive is replaced.

    However there is still a single point of failure - the disk subsystem itself.

    So you do need to keep a backup. One solution is an external hard drive the same size as the RAID array and backup to that - when you have backed up disconnebvt the drive and put it away in a safe place where it won't get dropped. And for speed you may want to look at an eSATA interface on the caddy.

    However remeber that as a mechanical device - hard disks WILL fail - the only unknown is when.

    The other (expensive) option is a tape drive, but then tyou are looking at SAS/SCSI controller and a drive as well, and although the cost per GB of storage is riduculously low, the initial investment is pretty high. (As I type I'm backing up a 250Gb partition onto an Ultrium 2 tape - tape cost £20) and so far it has taken 3 hours. That said I copied the same data from a USB caddy and that took over 5)
    (\__/)
    (='.'=)
    (")_(")

    Been helped or just 'Like' a post? Use the Thanks button!
    My broadband speed - 750 Meganibbles/minute

  13. #10
    Syd
    Syd is offline
    Hanging on the Edge Syd's Avatar
    Join Date
    Jan 2006
    Location
    Kent
    Posts
    1,636
    Thanks
    69
    Thanked
    32 times in 29 posts
    • Syd's system
      • Motherboard:
      • EVGA 760 Classified / MSI P35 / gigabyte gaming 7 1150
      • CPU:
      • I7 920@3.8 / E8400 / 4790k
      • Memory:
      • 18GB Dominator DDR3 1600 / 4GB / 16GB GSill
      • Storage:
      • 2 x Samsung 830 256/ 120GB Vertex 2 / Sam840's/ Sam SM951
      • Graphics card(s):
      • 690GTX on Water/IGP/ 980ti
      • PSU:
      • AX860/1250w Seasonic
      • Case:
      • TJ07 / PCV700
      • Operating System:
      • 7 64/ 10 64
      • Monitor(s):
      • NEC 3090 + Dell 2405PW
      • Internet:
      • Sky Fibre

    Re: NAS Raid Guidance Please

    This is the scary thing - CDR/BDR/HD all have a life and will fail at some point. I'm thinking that the only really important and irreplacable data is my photos, totalling about 150GB at present, so maybe a NAS to put my itunes library onto and phtos and then that will give me the ability to share and view over the network and then an external HD to back up onto. At that rate is there any advantage to running Raid Mirror ?





    My very first watercooled PC project log

  14. #11
    Senior Member watercooled's Avatar
    Join Date
    Jan 2009
    Posts
    10,858
    Thanks
    1,501
    Thanked
    935 times in 805 posts

    Re: NAS Raid Guidance Please

    IMO you're just wasting the space of the second HDD, stick it in a caddy and use it to back up instead.

  15. #12
    Syd
    Syd is offline
    Hanging on the Edge Syd's Avatar
    Join Date
    Jan 2006
    Location
    Kent
    Posts
    1,636
    Thanks
    69
    Thanked
    32 times in 29 posts
    • Syd's system
      • Motherboard:
      • EVGA 760 Classified / MSI P35 / gigabyte gaming 7 1150
      • CPU:
      • I7 920@3.8 / E8400 / 4790k
      • Memory:
      • 18GB Dominator DDR3 1600 / 4GB / 16GB GSill
      • Storage:
      • 2 x Samsung 830 256/ 120GB Vertex 2 / Sam840's/ Sam SM951
      • Graphics card(s):
      • 690GTX on Water/IGP/ 980ti
      • PSU:
      • AX860/1250w Seasonic
      • Case:
      • TJ07 / PCV700
      • Operating System:
      • 7 64/ 10 64
      • Monitor(s):
      • NEC 3090 + Dell 2405PW
      • Internet:
      • Sky Fibre

    Re: NAS Raid Guidance Please

    Quote Originally Posted by watercooled View Post
    IMO you're just wasting the space of the second HDD, stick it in a caddy and use it to back up instead.
    I'm probably missing somthing obvious here, but could I not run both drives as single vlumes in the nas box - using one to back up the other but not in raid ? hence saving another box and another caddy ?





    My very first watercooled PC project log

  16. #13
    Senior Member watercooled's Avatar
    Join Date
    Jan 2009
    Posts
    10,858
    Thanks
    1,501
    Thanked
    935 times in 805 posts

    Re: NAS Raid Guidance Please

    Ideally a backup should be separate from the main HDD for a number of reasons including protecting it from a failing power supply, power surges, physical damage, etc otherwise you're only protecting against drive failure in which case you might as well use RAID.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. new system advice please
    By bigduke6 in forum SCAN 3XS Systems Support
    Replies: 10
    Last Post: 17-01-2010, 12:39 AM
  2. Raid guide for beginners post edition
    By alsenior in forum PC Hardware and Components
    Replies: 2
    Last Post: 09-09-2007, 10:40 PM
  3. Raid NAS Again
    By alexkoon in forum PC Hardware and Components
    Replies: 2
    Last Post: 01-03-2006, 11:12 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •