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Thread: Raid X

  1. #21
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    I'm only using 1GB RAM now, going to up it to at least 2GB. Sheesh ^$^.

    RAID 5 is feasible.. 3 HDDs... but another few hundreds down the drain SCSI is out... hehee I not running server farm at home

  2. #22

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    then get the RAID 5 IDE la... wither SATA or PATA... if ur budget is ok la.. is super worth it man...

  3. #23
    vince123123
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    Just wondering, for RAID 5, the supposed principle is when one disk fails, you can just replace it and the RAID system will rebuild the data.

    However, I understand that RAID only works when you use HDDs of the same size (and I recall they said it has to be the same brand/model even). Now the question is, when one of hte disk fails in some years to come, how can we ever get a replacement disk of the same brand/model?

    Thanks!

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    Quote Originally Posted by vince123123
    Just wondering, for RAID 5, the supposed principle is when one disk fails, you can just replace it and the RAID system will rebuild the data.

    However, I understand that RAID only works when you use HDDs of the same size (and I recall they said it has to be the same brand/model even). Now the question is, when one of hte disk fails in some years to come, how can we ever get a replacement disk of the same brand/model?

    Thanks!

    Pay through your nose for repairs?

    Heh.. Most companies will have some form of maintainence contracts..
    Like the company my dad works for.... SGI specially had a 2GB SCSI drive repaired in USA and shipped it over for replacement..
    The cost of repairs was probably enough to buy a spanking new 18GB SCSI drive at the time..

    Anyway, you should always have hot spares. These are extra drives hooked up to the controller but not used. When any drive fails, the hot spares will be used immediately to rebuild the array.

  5. #25

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    Quote Originally Posted by vince123123
    Just wondering, for RAID 5, the supposed principle is when one disk fails, you can just replace it and the RAID system will rebuild the data.

    However, I understand that RAID only works when you use HDDs of the same size (and I recall they said it has to be the same brand/model even). Now the question is, when one of hte disk fails in some years to come, how can we ever get a replacement disk of the same brand/model?

    Thanks!
    IIRC, say you have 120 + 100 GB HDD.... using RAID, you waste the 20 GB on the 120 HDD

  6. #26
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    Default Raid 5

    In the longer run, RAID 5 is more value for money... At the start, RAID 1 use 2 disk, RAID 5 uses minimum of 3. But the usable amount for RAID 1 is ALWAYS 50% (n/2, n an even number). RAID 5 is (n-1)/n for any # of drives. You can choose to add more disk later on and the efficiency increases.

    Some newer MB already adding hardware SATA RAID-5 so...

    BUY! BUY! BUY!

  7. #27
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    But do you need to keep adding disks of the same size and brand/model?

    hmm....i'm more concerned with how to rebuild the array when one disk fails and how to find that disk again some years later when that model is obsolete.

    Quote Originally Posted by Watcher
    In the longer run, RAID 5 is more value for money... At the start, RAID 1 use 2 disk, RAID 5 uses minimum of 3. But the usable amount for RAID 1 is ALWAYS 50% (n/2, n an even number). RAID 5 is (n-1)/n for any # of drives. You can choose to add more disk later on and the efficiency increases.

    Some newer MB already adding hardware SATA RAID-5 so...

    BUY! BUY! BUY!

  8. #28
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    Quote Originally Posted by mervlam
    IIRC, say you have 120 + 100 GB HDD.... using RAID, you waste the 20 GB on the 120 HDD
    Yup, that's correct.


    Watcher Buy your head

    Quote Originally Posted by vince123123
    But do you need to keep adding disks of the same size and brand/model?

    hmm....i'm more concerned with how to rebuild the array when one disk fails and how to find that disk again some years later when that model is obsolete.
    You can add beyond the size of the HDDs, I'm not too sure what will happen when you change from 3 x 120GB to 3 x 200GB, would the array update itself to 200GB when you plug in the final HDD or not is unknown. But unlikely.

    The rebuilding automatically takes place when you add in the HDD, it should be automated using hardware RAID.

    Even if you get a 2000GB next time to replace a 200GB, you'll probably back up all the data after inserting a new HDD and rebuild the array with 2 x 2000GB. Just a thought. By then it should be dirt cheap!

  9. #29
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    so you're saying that even when one of the disks in the array fails, I can just get another disk of differnt size and model to replace that failed disk? Hmm this appears to be good, yet different from what I thot raid was abt, that u need same size disks and preferred same model.



    Quote Originally Posted by espn
    Yup, that's correct.


    Watcher Buy your head

    You can add beyond the size of the HDDs, I'm not too sure what will happen when you change from 3 x 120GB to 3 x 200GB, would the array update itself to 200GB when you plug in the final HDD or not is unknown. But unlikely.

    The rebuilding automatically takes place when you add in the HDD, it should be automated using hardware RAID.

    Even if you get a 2000GB next time to replace a 200GB, you'll probably back up all the data after inserting a new HDD and rebuild the array with 2 x 2000GB. Just a thought. By then it should be dirt cheap!

  10. #30
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    Not really, it's just that you might not be able to fully utilize the disk if you were using 3 x 120GB and suddenly you plugged in a 250GB to replace a faulty 120GB

    Of course, if everything is similar, that would be the best scenario

  11. #31
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    hmm, well that wouldn't be too much of a problem as I'm concerned only with data intergrity and redundancy. once the first of the array fails, I'm going to copy all of the data onto a freshly built array as it is a sign that the rest may fail sooner or later.

    Quote Originally Posted by espn
    Not really, it's just that you might not be able to fully utilize the disk if you were using 3 x 120GB and suddenly you plugged in a 250GB to replace a faulty 120GB

    Of course, if everything is similar, that would be the best scenario

  12. #32
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    I'm running RAID 1 using 2 x SATA 250GB HDD for storage.

  13. #33
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    RAID is meant for bringing your system back online fast with minimal lost of data.. Not so much as to protect all yr data...

    If your PC caught fire, electrical oversurge, kana bombed, etc... the data are still juz as lost... There why people still use backup even though they use raid.. and the backup data are usually keep far away from the existing system in case of disaster!

  14. #34
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    Thanks for your advice.

    I guess I'm primarily interested in making sure hard disk failure doesn't result in loss data for now.

    I am still exploring ways to get an easy backup done. At present, I have almost a Terabyte of stuffs to backup if I am going to back up stuffs. Do you have any suggestions on a cost efficient way of backing up my data? Copying to DVDs seem to be a little difficult as it would involve hundreds of them.

    Quote Originally Posted by Ashleyy
    RAID is meant for bringing your system back online fast with minimal lost of data.. Not so much as to protect all yr data...

    If your PC caught fire, electrical oversurge, kana bombed, etc... the data are still juz as lost... There why people still use backup even though they use raid.. and the backup data are usually keep far away from the existing system in case of disaster!

  15. #35
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    Quote Originally Posted by vince123123
    Thanks for your advice.

    I guess I'm primarily interested in making sure hard disk failure doesn't result in loss data for now.

    I am still exploring ways to get an easy backup done. At present, I have almost a Terabyte of stuffs to backup if I am going to back up stuffs. Do you have any suggestions on a cost efficient way of backing up my data? Copying to DVDs seem to be a little difficult as it would involve hundreds of them.
    DVD dash technology is not advisable.. Try DVD+ instead.. Even then I'd keep 2 copies in different locations.
    The DVD format wasn't implemented with very strong error correction capabilities so even a single scratch that's deep enough can render the disc unreadable unlike CD's (the error correction for CD's was way overdone for audio but great for data).

    For very large backups, try DLT's. It might be a hassle with all that rewinding and all but they do pack a hell lot of data. As with DVD's, I'd keep 2 copies in case of fungus etc..

  16. #36
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    I'm ok with the rewinding bit as I don't backup THAT often. A preferred way would be to do a full backup of all my 1TB once, and then incremental or differntial backups thereafter.

    Do you know how much and what models of DLTs are available? I heard that these drives go in the range of thousands of $.

    Quote Originally Posted by Firefox
    DVD dash technology is not advisable.. Try DVD+ instead.. Even then I'd keep 2 copies in different locations.
    The DVD format wasn't implemented with very strong error correction capabilities so even a single scratch that's deep enough can render the disc unreadable unlike CD's (the error correction for CD's was way overdone for audio but great for data).

    For very large backups, try DLT's. It might be a hassle with all that rewinding and all but they do pack a hell lot of data. As with DVD's, I'd keep 2 copies in case of fungus etc..

  17. #37
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    Quote Originally Posted by vince123123
    Thanks for your advice.

    I guess I'm primarily interested in making sure hard disk failure doesn't result in loss data for now.

    I am still exploring ways to get an easy backup done. At present, I have almost a Terabyte of stuffs to backup if I am going to back up stuffs. Do you have any suggestions on a cost efficient way of backing up my data? Copying to DVDs seem to be a little difficult as it would involve hundreds of them.
    haha.. in spite of all the technology advancement... there's no really ideal backup system.. Using DVD & CDs is a cheaper option.. even though u may run up to hundreds of disks... just sort them out and lable them correctly will help a lot.

    DLT Tape drives are faster way of backup, the tapes itself is cheap.. ard $10 onwards.. but the drive is anything from ard $500 for a single tape drive to a few thousand for a muliple tape, auto loader tape drive..

    Tape backup is good if you backup regularly.. if u only do it once a month.. or less.. not much use except for the fact that yr data ain't a complete lost. U only lose data till yr last proper backup..

    Another form of effective but costly backup is to copy yr data to a remote server located elsewhere...

  18. #38
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    Quote Originally Posted by vince123123
    Do you know how much and what models of DLTs are available? I heard that these drives go in the range of thousands of $.
    Yeah, they are all about there.. At least $1.5k for a drive.. Depending on the type of (S)DLT used, you can have storage from 80GB compressed (2:1) per tape up to 600GB compressed per tape.

    Most of them run off SCSI as well so you have to factor in the cost of a U160/ U320 SCSI adaptor.

    Affordable solution would be using DL, DS, DVD+R but they're quite a bitch when you've got 1TB of stuff to backup. If it's a business, go ahead and get DLT's. Write off the cost under the accounts.. If it's for home use, I don't think you should pay that kind of money for storage..

  19. #39
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    Cheapest HP tape drive currently is prob the HP Storageworks DLT VS 80 for a 40GB tape backup at US$1199.00 internal & US$1399.00 external drives

    Not so sure abt other brands.. but their price range are pretty close too...

  20. #40
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    Quote Originally Posted by Ashleyy
    Cheapest HP tape drive currently is prob the HP Storageworks DLT VS 80 for a 40GB tape backup at US$1199.00 internal & US$1399.00 external drives

    Not so sure abt other brands.. but their price range are pretty close too...

    That's actually a Tandberg VS80 I believe.. Which is available from Taknet at about S$1.7k+ for the internal kit. Almost S$2k for the ext. kit..

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