Discussion Forums > Technology

RAID Boxes

<< < (3/7) > >>

bcr123:
Raid can accomplish different goals depending on how it's setup:

For small raids (2-4 disks)

Raid0 - maximum performance -- by distributing the read/write IO across multiple physical disks, for systems that need to move a lot of data but don't need to store it long term (think of scratch disks for example) It's not a big deal any more with TB+ disks available but it also allowed creation of very large partitions by combining multiple disks back when individual drives were small. The big disadvantage of RAID0 is that failure in any one drive loses all data on the set, so you are adding risk to gain speed.

Raid1 - maximum redundancy -- by duplicating the data on multiple drives hard drive failure is a non-event (usually), same speed as a single disk though.

Raid5 - Better than stock speed, minimal hardware to achieve redundancy, IO, data and parity is spread across multiple disks, minimal amount of "wasted" capacity to achieve redundancy, can recover from a single disk failure easily but performance is reduced during the rebuild of the failed disk, generally used where high-availability and good performance is crucial (servers). RAID5 requires 3 disks minimum to operate, it's practicality is limited to the 4-8 disk range, above 8 you start thinking Raid6 for enhanced redundancy.

halfelite:
A good thing to remember software raid cannot always be moved to a new system. IE if the software is part of the bios. If you run nix and use something like mdadm then you can easily move it to a different machine.

Arveene:

--- Quote from: fohfoh on August 03, 2009, 01:52:42 PM ---Now, looking at the pictures above, I assume you want to have a mirror "backup". This looks into raid 1, 5, 6. Now, I can't really get into the differences, but how it works is this. You have 2 sides with approx equal HDD space. So, either you can do 1TB:1TB or 2x 500GB:1TB etc. (as long as you somehow can set it up hardware wise.) One side is used as the system use. (anime watching, storing, etc.) the other side is a total copy for stability purposes. (sort of like a backup of company files, and not a backup in the sense of "backing up" random files). "Now how it works is this. " remember the days before daemon tools? The "back up burn of your favourite game"? How it works is this. You have 2. One gets scratched to shit and unusable. The other "backup" is used. You replace that destroyed copy ASAP. Same case here except the data is always updated and not "set in stone" like a burned disc.

--- End quote ---

I bolded the important part. If I'm reading that correctly, you're mentioning 3 drives? 2x 500GB drives, and 1x TB drive? Unless you're using JBOD (waste of time), any RAID setup using those 3 size drives will only use 500GB of the 1TB drive, not to mention you can't use RAID 1 or 10 (01) with 3 drives. I don't know of any RAID controller that can use the 2x 500GBs as a TB and mirror it onto another.

Then there's hardware vs software RAID, and even with a RAID card for an external solution it's not always a full hardware RAID. It's important to look into the details and differences between software, hardware, and fake hardware RAIDs. Like kureshii said, we could discuss RAID for days.

halfelite:
and if you are going to start a raid project make sure you budget it out first. good hardware raid cards run in $500-1000 depending on how many ports, what the proc speed on the card is and how much cache it comes with.

zfs in opensolaris has been showing some good points but its very confusing to setup for first timers.

fohfoh:

--- Quote from: Arveene on August 03, 2009, 07:33:13 PM ---
--- Quote from: fohfoh on August 03, 2009, 01:52:42 PM ---Now, looking at the pictures above, I assume you want to have a mirror "backup". This looks into raid 1, 5, 6. Now, I can't really get into the differences, but how it works is this. You have 2 sides with approx equal HDD space. So, either you can do 1TB:1TB or 2x 500GB:1TB etc. (as long as you somehow can set it up hardware wise.) One side is used as the system use. (anime watching, storing, etc.) the other side is a total copy for stability purposes. (sort of like a backup of company files, and not a backup in the sense of "backing up" random files). "Now how it works is this. " remember the days before daemon tools? The "back up burn of your favourite game"? How it works is this. You have 2. One gets scratched to shit and unusable. The other "backup" is used. You replace that destroyed copy ASAP. Same case here except the data is always updated and not "set in stone" like a burned disc.

--- End quote ---

I bolded the important part. If I'm reading that correctly, you're mentioning 3 drives? 2x 500GB drives, and 1x TB drive? Unless you're using JBOD (waste of time), any RAID setup using those 3 size drives will only use 500GB of the 1TB drive, not to mention you can't use RAID 1 or 10 (01) with 3 drives. I don't know of any RAID controller that can use the 2x 500GBs as a TB and mirror it onto another.

Then there's hardware vs software RAID, and even with a RAID card for an external solution it's not always a full hardware RAID. It's important to look into the details and differences between software, hardware, and fake hardware RAIDs. Like kureshii said, we could discuss RAID for days.

--- End quote ---

Oh, it can't be done? I guess I was given wrong information then. Someone said they set up a raid with 2x500GB+1TB with 2x 1TB on the other side and was recommending those WD Scorpio green or w/e for low power use on the other side of the raid.

Sorry, wrong info. Thanks for the correction.

Navigation

[0] Message Index

[#] Next page

[*] Previous page