Stick with larger Raid 1 or go to Raid 5?

I'm trying to update my current backup sit.
Currently, I backup my machine daily (small transfer as I only do incremental) to a Guardian Maximus in RAID 1 config.

I have two of the GM units and I rotate between them taking one home every day in a Pelican as offsite insurance. A third offsite GM is synced ever 4 weeks and put in SDB.)

I'm ready to either upgrade the HDs to a bigger size (running out of room) or update my setup completely.

I ordered a Raid unit from OWC that holds 4 drives and does pretty much every raid version. My intention was to setup 4 drives and do two Raid 1 mirrors. 1 volume for basic data and another for the work video archive. Turns out it only does Raid 1 if you have only two drives in it and you cannot do multiple raid 1 configs. My fault, I mis-read the datasheet.

I'd like to draw on everyone's experience and expertise and ask your opinion. Should I simply upgrade the HD's in the GM units to hold ALL the data and keep doing what I'm doing or should I bite the bullet and go to the Raid 5 setup on the new system and buy a second one as an offsite?

I realize many would say it makes more sense speed-wise to do so, but I don't care about speed, I care more for viable data. Using the protocol I have now ensures me that at any given time I have at least one HD with viable data. We're not setup for tape and I need to ensure my data. Raid 5 scares me only because if the array is broken, it's possible it could fail if more than one disk fails. If the parity disc went and one of the others, I'd be screwed.

Any thoughts? Ideas?
4 answers Last reply
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  1. RAID5 dont bad performs very poorly, and RAID5 in general if something goes utterly wrong is tough to get data off - be careful

    RAID10 may help you, its like 2xRAID1's - its literally a RAID'd RAID1 lol your device should do it aok
  2. Well, you didn't specify the amount of data you are backing up, so I'm kind of flying blind here. If the amount of data is something you handle by upgrading the drives in the GM's, then that would be the most cost effective solution. a RAID 5 volume is extremely secure, as long as you don't let two drives fail in it. There isn't a "parity" drive, as all parity data is striped across all drives in the array. RAID 5 arrays allow for a larger array size, since you aren't doing a 1:1 mirror of data on your disks. Any failed drive in a RAID 5 can be recreated using the parity data from the remaining drives. But even though 2 drive failures in a RAID 5 can be bad news, that's the same with the RAID 1 you have now. If 2 drives failed in your 2 drive RAID 1, you'd be in trouble anyhow. RAID 5 is good for extremely large volumes that require redundancy. RAID 1 is limited to the largest single drive you can get. But since I'm unaware of the amount of data you need to back up, it's hard to make a recommendation. The way you're doing it now sounds very secure, and if you can upgrade the drives in the GM's to a size that is suitable, then I would go that route. If not, a pair of OWC's with 4 large drives in a RAID 5 could make sense.
  3. apache_lives said:
    RAID5 dont bad performs very poorly, and RAID5 in general if something goes utterly wrong is tough to get data off - be careful

    RAID10 may help you, its like 2xRAID1's - its literally a RAID'd RAID1 lol your device should do it aok

    RAID 5 only performs badly if improperly implemented. A RAID 10 isn't going to gain any storage space, it will just increase the speed of the array. You're still limited by the size of the largest disk available. If you used 3tb drives, it would take 4 to do a 6tb array in a RAID 10. If speed isn't an issue, like lymond mentioned, you could get the same 6tb with a RAID 1 by only using 2 drives. A RAID 5 with (4) 3tb drives would net 9tb of redundant volume space. The only down side I see to using an OWC enclosure with a RAID 5 setup is that if the RAID controller in the enclosure dies, your data is stuck on the drives and you would have to move them into another OWC enclosure to get the data off. If you did a RAID 1, each individual drive could be pulled and accessed in any other enclosure or system, since the disks are not spanned, and are all identical.
  4. The more drives you have in a RAID, the more efficient it is. Say you want to store 750GB of data, you need 2 drives of 750GB each in a RAID 1, so your efficiency is 50%. But if you go to RAID 5 then you could use 4 drives of 250GB each, and now your efficiency is 75%. But then IMO arrays with a large number of drives only make sense if you have a whole lot of data to store. For even as much as 2TB, just buy a pair of drives and mirror them.
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