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Thread: Everybody needs RAID! please do so today!

  1. #21
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    Default Re: Everybody needs RAID! please do so today!

    Quote Originally Posted by Hacker View Post
    Why not? If you are using 2 disks for RAID 1, failure of 1 disk is acceptable and no different from you using RAID 5, say, with 3-4 disks? If you are using a total of 4 disks to mirror, then 2 disks can fail if not in the same mirror.
    Yes, you're right when it's commercial hardware, other than poorer performance for RAID5. What you state is correct.

    I'm warning against fault tolerance that use more than 2 HDDs, in PC mainboard or cheap raid card. These does not have the same reliability as the commercial variant. There's a high chance that you boot your PC and one of the 3 or 4 HDD does not get detected or one hardware goes bad. It comes back online but needs to be rebuild, and a second HDD goes offline during boot.

  2. #22
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    Default Re: Everybody needs RAID! please do so today!

    BTW, HDD used in most if not all SLS raid based mainboard or raid card are compatible. Meaning you remove one of the two RAID1 HDD and put into another brand, your data is still intact. This is not likely to be true when configured for RAID5 or RAID0+1. If raid controller fail, you must find back the same hardware and/or controller, which can be tough after a couple of years.

  3. #23
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    Default Re: Everybody needs RAID! please do so today!

    Quick reply doesn't work, sux0rz.


    Anyway, get the Sun StorageTek 6140. Configured one the other day, shiok, 7 x 143GB. RAID 5 + 2 hot spares. Songst.

  4. #24

    Default Re: Everybody needs RAID! please do so today!

    RAID is for cockroach....you know, the spray... *psssssssssssst*

    A good (and preferably automatic) backup system works wonders.

    There is another story I could tell about how all my image files on a hard disk mysteriously got scrambled. No filesystem damage, no obvious damage, no impact damage, yet all of my files had color streaks, JPEG artifacts, and missing/corrupted halves of the image. You can probably guess that I freaked out, absolutely freaked out.. all my work.... no RAID would have saved me since the corrupted data would have been written to all disks in the array. It is the strangest thing I have ever seen in all these years and there's no logical explanation as to why. The files and the file system even look fine after all the checks!

    I didn't lose sleep though, thanks to multiple offsite backups. But I got a lot better at backing up.

    DVD's do degrade over time. It's advisable to re-burn the images to new media and new technology as it becomes available (CD-Rs to DVD-Rs, BD-R when the prices come down in the near future, etc.) Ultimately you become your own 'digital librarian' and with it comes management of the file library.

    And don't forget you can still make nice prints and keep them for a long time..
    Last edited by sloth; 19th July 2007 at 07:36 PM.

  5. #25
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    Default Re: Everybody needs RAID! please do so today!

    Quote Originally Posted by MadCat90t View Post
    Yes, you're right when it's commercial hardware, other than poorer performance for RAID5.
    Whether it is RAID 1 or 5, does not read/write also matter depending on what is more important? What about having more spindles?

  6. #26
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    Default Re: Everybody needs RAID! please do so today!

    Quote Originally Posted by sloth View Post
    RAID is for cockroach....you know, the spray... *psssssssssssst*

    I didn't lose sleep though, thanks to multiple offsite backups. But I got a lot better at backing up.
    Don't off site backups use RAID also?

  7. #27
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    Default Re: Everybody needs RAID! please do so today!

    RAID sucks. It sucks because people relies on it and never do backup. My job is to manage Unix servers with RAID, soft and hard RAID. In both cases, I always have problems because of RAID. Don't rely on little SATA RAID, on paper it works, if hard disk crash, you have just chance to lose everything (or not, it depends).

    Just do backup, backup what you want to save. That's the only reliable way.

  8. #28

    Default Re: Everybody needs RAID! please do so today!

    I store my photos and stuff on HDD then I backup once a month to a external HDD. I think I should do the same for the family photos (Its on a seperate HDD thats 6 years old)
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  9. #29
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    Default Re: Everybody needs RAID! please do so today!

    Quote Originally Posted by JoshSiao View Post
    I store my photos and stuff on HDD then I backup once a month to a external HDD. I think I should do the same for the family photos (Its on a seperate HDD thats 6 years old)
    What is the chance of a HDD failure???

    I was thinking of getting a usb external hard disk......
    Art is perception; Perception is art.

  10. #30
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    Default Re: Everybody needs RAID! please do so today!

    Quote Originally Posted by Halfmoon View Post
    What is the chance of a HDD failure???

    I was thinking of getting a usb external hard disk......
    it may happen anytime. There's no way of telling. Maufacturers uses MTBF (http://www.weibull.com/hotwire/issue22/hottopics22.htm) but it's a guage.

    I'm posting for the sake of anyone who still do not have any means of backing up still and not even considering at all. DVD, CD, external USB etc all work, just do backup for your own sake.

    Discussing about RAID levels can go on and on and on so see what suits you best and go for it.

    If you're interested in RAID and wanna read, google or se these 2.

    http://www.slcentral.com/articles/01/1/raid/
    http://www.acnc.com/04_00.html

    The AC&C one i feel has better explaination. Then check out some motherboards that have raid chip on them, start with RAID1 and if need, you can always add hdd (depending on the mobo model/ brand you buy) and change the level to other RAID level, 1 to 0+1 to 5 or whatever in between and vice versa.

    SOHO or home NAS are good options too. many has pointed out. Good pricing with hdd bundled nowadays make it even more affordable. Look for those that runs some simple Linux/ web server (apache) OS in them and serve your photos directly from your NAS to the web.

    Having a plan for backing up is one thing, testing and running through it is another. Try a failover exercise. See if you can really get your data back from your RAID, DVD/ CD/ external hdd/ NAS etc etc. It's the only way you know you are safe.

    Be paranoid! Be very paranoid about your data and photos please!

    Happy RAIDING/ Backing-up. You'll be glad you did one day but we all hope that day never comes!

    Few more hours and it'll be day break, have recover almost 70% of my fren's photos. Using software still manage to work after replacing some hardware on the hdd itself. Manage to find a good part from an exact model and it's spinning again.

    This weekend, shopping for this friend. He'll buy anything recommended now. haha A really hard lesson learnt. RAID 5 plus NAS will be his new setup.

    Quote Originally Posted by melnjes View Post
    DVDs can degrade too over time.

    I store mine over DVDs and a few hard disks. Harddisks are located at separate physical locations, in case of fire.
    You are really good!

    Quote Originally Posted by AJ23 View Post
    Haha, think one have not heard of my Ultra320 SCSI RAID5 setup on a $100k server that failed. (2 of the expensive HDD died at the same time, how lucky can that be?)

    I think TS is getting a little too excited. As previous poster has said, it's BACKUP, and regular scheduled backup if one think the the pictures are important to be archived.

    Also, dun need to build a RAID5 machine, it's not cheap and easy especially for the IT uninitiated. A RAID1 (mirror) would probably suffice.
    i'm not excited at all. i'm tired of telling people actually. Yes, building for a non IT guy or gal may be a really daunting task thus the suggestion of NAS by those who has replied, i think is a good option too. USB hdd are by far, simplest. A few won't hurt either.

    any RAID 5 be it Ultra320 SCSI or anything fails when 2 or more hdds fails at once. I guess you know that already. There's proitertary RAID by big boys like IBM and HP that they themselves call RAID level 6 or enhance 5. whatever it is called and it's implement, it's the cost. Home users may not have the use of it either. Who'll needed enhanced raid 5 with SAS harddisk at home?

    I believe many people without a plan should have at least get the idea of doing a backup as Poet has describe or thinking of their next purchase of a NAS or building a RAID rig if you have the knowledge after reading this.

  11. #31
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    Default Re: Everybody needs RAID! please do so today!

    Quote Originally Posted by Hacker View Post
    Don't off site backups use RAID also?
    yes, there's also geographical RAID (different location/ countries) even through WAN links/ metro E, lease lines etc but that's like really off topic. Let's discuss on home users specific.

  12. #32

    Default Re: Everybody needs RAID! please do so today!

    etegration, what you were saying and later advocating are 2 different things. But no point arguing and mincing words, the important thing, as you said it, is to back up everything, and do so diligently.
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  13. #33
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    Default Re: Everybody needs RAID! please do so today!

    Quote Originally Posted by stougard View Post
    RAID sucks. It sucks because people relies on it and never do backup.
    Poor implementation and using poor equipment does not equate to the same thing. Many people rely on RAID and also do backups with RAID. Not sure how the two are mutually exclusive. (I use RAID, therefore I do not backup. I do not use RAID, therefore I backup).

    So if I claim UNIX sucks because every single unix system has failed, what conclusion can you draw?

  14. #34

    Smile An alternative perspective from a former IT professional

    Greetings,


    13 years in the IT industry does not make me an authority but it has given me quite a perspective on what works and what simply costs a lot of money. We configured terabytes of RAID disks on Sun servers for our Oil & Gas client on then 32/64-CPU machines. Needless to say these are mission-critical computers and every second of downtime costs fortunes. We've used disks from Seagate, IBM/Hitachi, etc and no one is particularly more reliable than the other and when they are Fast Wide UltraSCSI 10,000-15,000 RPM a lot of heat are produced running 24 x 7. When these disks failed, they failed big time. We had to keep reasonable amount of spares all the time!

    Snapping out of that into our homes or offices, it boils down to whether RAID becomes a necessary evil or a burden and a costly failure when it fails. Having seen such extremes that I hope never to see or experience in personal capacity, I adopted a simpler and more cost-effective approach ... 3 x SATA Disks inside casing, and 3 x IDE vis USB Enclosures, all 7200-rpm and totalling 1.3 Terabyte and non-RAID. The PC has enough USB 2.0 slots to handle more disks but enough is enough. I have my PC with dual monitors and the 3 USB disks on 3 UPS. Power inconsistencies and spikes can just as easily kill them. There's no end as to how far one can go!

    Images I cannot afford to lose are backed up onto Verbatim DVD+R. Images that I have already delivered to clients are on client's onus to back them up. They are left on my HD and are also backed up on DVD. I do not commit to client for making their images available indefinitely.

    Everything we do in photography carries a risk. The question is whether you've done your due-diligence in fulfilling your contract with the clients. How many backup can you really afford to have, and how many more backup of backup do you need before it becomes insane? Facing failures is one of the many necessary life challenges we must encounter, unfortunately.

  15. #35

    Default Re: Everybody needs RAID! please do so today!

    I back up more or less religiously. The few times I did not do that, it came back to haunt me big buck$.

    Right now, I have the system back up the 3x500GB SATA HDD inside the casing automatically every night onto 2x400GB, 1x300GB and 3x150GB HDD in external casings via firewire and USB. Rather clumpsy, but it works.

    Final image files are also backed up on DVDs. Each DVD holds about 80 images, tiffs and raw. This is the part that I am concerned about. Right now, I have 33 such DVDs. The oldest is now just over 24 months. Checked it, still readable. But as we all know, DVD we burned will fail some time. Question is when. Another equally pressing question is how to do long term archival storage. Re-burning DVDs annually or even biannually is really not an option.
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  16. #36
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    Default Re: Everybody needs RAID! please do so today!

    This is a scary scenario that repeats itself often.
    Had a near miss once.
    Now my setup is 2 RAID 5 NAS 1 backing up the other.
    I run the backup over the night or weekends and it copy those files that I work on from one NAS to the other as well as my temp files on my C drive.

  17. #37

    Default Re: Everybody needs RAID! please do so today!

    I try to have at least 2-3 active copies of the files in PC and laptops and 2-3 copies in portable HDD, DVDs

    nothing is foolproof for sure, however the probably of all these forms of storage failing at one time is low. Thus if any of them is found to be down, they can be replaced instantly from another source, sort of a parrallel support system..

  18. #38
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    Default Re: Everybody needs RAID! please do so today!

    Quote Originally Posted by CYRN View Post
    cuz raid5 critical failure point is the controller.

    aniway RAID 5 would onli be useful if you have 5 disk or more.. else for those budget constrained wif a 3 disk setup... better off wif 2 disk raid 1.
    Does not RAID 5 also use controllers? Why are 5 disks more beneficial than 3-4 disks in a RAID 5 configuration? For budget constraints, why is RAID 1 better since usuable space is 50%?
    Last edited by Hacker; 20th July 2007 at 10:25 AM.

  19. #39

    Default Re: Everybody needs RAID! please do so today!

    Don't waste time with RAID, just go an get an external harddisk, plug in and start using, simple and reliable.

  20. #40

    Default Re: Everybody needs RAID! please do so today!

    Well, I'm also in the IT industry and i would like to shed some lights on today's enterprise storage.

    If you want to use many spindles on a SAN, My advice is to create smaller Raid groups. I would then create a LUN across many Raid Groups on the Storage Controller to form a really huge volume if that is required.

    You might ask, why waste the extra disk space? This is because that chances of having 2 Drives in the smaller raid group failing at the same time are lower. Assuming MTBF of 2000000 hours. Probability of having a 16 drive raid failing is 16/2000000 X 15/2000000 X Time taken to repair and probability of having a 6 drive raid group failing is just 6/2000000 X 5/2000000 X Time taken to repair. This is a eight fold increase in the probability of failure of the entire raid group if we assume that the time taken to repair is the same. This is unfortunately not true as the bigger the Raid Group, the more time is required to recalculate all the blocks.

    Raid Group rebuilding time is a huge consideration for corporates. Having a smaller data set to rebuild will be so much better as all these rebuilding activity keeps the drives and Storage controller really busy. Busier drives will always go down sooner than you think (even Enterprise grade Fiber Channel drives are the same). You certainly do not want another drive to go down during rebuilding.

    Although Raid6 technology(Double parity striping) is invented to circumvent this failure, rebuilding those huge volumes takes a big hit on performance on the Storage controller. This affects all the RAID groups on your storage controller. Not just that particular RAID group data. Imagine rebuilding 8 TB of data running Raid6 on 12X750GBX7200RPM SATA disks.. it will take close to a week literally. This performance hit will be totally unacceptable for systems demanding fast data access to the SAN.

    Theres a thinking that more spindles in the RAID group equates to faster performance. But this is only true up to a point where the performance gains are really negligible. You have drive access time latency to think of too. The whole raid group is as fast as the fastest drive on the group. Latency is also introduced in the coordination of the multiple reads/writes to the all the disks. Big Raid groups are not so much a problem if you are writting files every now and then but not when it comes to pumping in/out data constantly. We call these Peak IOPs vs Sustained IOPs (Input/Output per second). Most SAN manufacturer simple states the PEAK Cached IOPs performance and this is misleading.

    In the end of it all, there's no running away from backing up. You can avert a computer hardware disaster anytime but what if the entire infrastructure gets burned down? Rich corporates can afford to have SAN replication down over the network but for SMEs, the best bet would be a tape in a safe location.

    For home users, implementaing RAID technology is good if you have enough $$ in the pocket. But ultimately you would still have to backup your data in case your place burns down. I would suggest you guys to look at some System protection software instead. Try Acronis True image or Symantec's Backupexec System Recovery Desktop Edition. You can set it up to image your computer to your NAS or spare hard drive or even portable hard disks. Then make a copy of the system image created by the software to a DVD or Portable Hard drive and keep it in an alternative place(Work/Car or Parent's house) just in case disaster strikes.

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