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Operating System Specific Discussions => Other Operating Systems => Topic started by: trekiej on June 24, 2010, 04:20:51 AM
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I am planning to build a new computer and I wanted to get some advice on Raid5 and Raid 1+0.
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I am planning to build a new computer and I wanted to get some advice on Raid5 and Raid 1+0.
My advice to you:
RAID is for availability, not continuity. No matter which solution you select, make regular backups of all the data you can't afford to lose.
If you have enough money, get a hardware RAID board. You can tell by the fact that they are expensive. ;-)
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I am planning to build a new computer and I wanted to get some advice on Raid5 and Raid 1+0.
Personally I use a large NAS (4 x 1.5TB HDD) and a server (3 x 1.5TB) RAID-5 setups to store data. My desktop machines have only relatively small SSD HDDs. The NAS/server storage is available to all my computers in my home LAN.
If you're going to use large capacity drives, use RAID-6 rather than RAID-5. I already am pushing it with RAID-5 containing 4 1.5TB HDDs. If one of those HDDs should fail, it already is quite likely that 2nd one fails during the rebuild.
Also, as already mentioned RAID itself doesn't replace backups. So remember to backup our important data even when using RAID.
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I'm planning to have a striped main drive and then another drive as manual back up. The most likely problem would be a virus corrupting the drive and it doesn't seem very safe to have everything split in two.
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I am planning to build a new computer and I wanted to get some advice on Raid5 and Raid 1+0.
Raid doesn't guarantee your data integrity. It doesn't detect silent data corruption for instance.
At present the best solution to preserve your data is to use ZFS as filesystem. It's available for Solaris, OpenSolaris, FreeBSD and Linux (in user space only - kernel module version still under development).
To have an idea of ZFS benefits take a look at this article: http://constantin.glez.de/blog/2010/01/home-server-raid-greed-and-why-mirroring-still-best
There are a lot of other interesting documents about ZFS on the web...
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I am planning to build a new computer and I wanted to get some advice on Raid5 and Raid 1+0.
* All but a few so called "Cheaper" NAS Raid devices have any decent transfer rates. i.e Gigabit networking doesn't necessarily mean Gigabit Transfer speeds, and most aren't anywhere close to a PC with the same.
* "Fake" Raid is common on many cheaper raid controllers and many built-in mainboard raid controllers. The upshot is that its just in enhanced software raid and many OS's don't support it well.
* I can recommend Adaptec SATA Raid controllers specially the 4, 6, or more port cards as they are hardware raid. (Sadly however Adaptec have been bought out so support will diminish.)
* Depending on the resilience you want Raid 1 and Raid 1+0 is the by far the most resilient, Raid 5 is much weaker, unless you use a hot spare.
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I wanted to get some advice on Raid5 and Raid 1+0.
RAID5: You will need at least 3 disks. Net. capacity will be 2 disks then.
RAID1+0: You will need at least 4 disks. Net. capacity will also be 2 disks then. Will be faster than RAID5
In general I would advise to buy a fast SSD nowadays instead of filling up your computer with a pile of power consuming, noisy, heat generating conventional drives. At least if we a talking about a desktop. If you need a lot of space, think about a NAS solution as others mentioned before.
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RAID5: You will need at least 3 disks. Net. capacity will be 2 disks then.
RAID1+0: You will need at least 4 disks. Net. capacity will also be 2 disks then. Will be faster than RAID5
Small clarification: Faster than RAID5 when writing. Reading is pretty much the same.
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I use a RAID5 setup with 4x WD Caviar Blacks on a dedicated RAID card (Areca 1222 PCIe).
This array of 4x1TBs gives an effective capacity of 3TB, and transfer speeds are extremely fast as the controller accelerates RAID5 operations in hardware with none of the overheads in processing incurred by using a software RAID solution (as commonly found using on-board motherboard controllers for RAID). It also has a 128MB cache on board.
The Areca is a joy to work with, it's an expensive card but very robust and intuitive to set up.
You can split the array up how you like so they appear to the machine and OS as more than one "drive" if you like. For example, my 3TB array is split into two "drives", one 120GB for operating systems, and the rest as storage for programs and data. This is useful for situations where the array size is too big for an MBR partition scheme, or where setting up a multi-boot environment with lots of extended MBR partitions could be a headache to get working.
The card has a web interface accessible via the driver to configure and monitor it, and also has an Ethernet port so it can be accessed from another terminal on the network, but also broadcast warnings and other information to wherever an administrator may be monitoring.
I chose the Areca for its excellent driver support; it has drivers for all flavours of Windows, both 32 and 64bit. Linux support is in the kernel, and MacOS X has support for it built-in for use in a hackintosh application (;)) or for use in a Mac Pro.
It is a server-class card with tons of features, and probably excessive for a home machine, but I can recommend it.
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I am planning to build a new computer and I wanted to get some advice on Raid5 and Raid 1+0.
Depending on your use of the computers storage.
RAID 0 Stripes multiple disks together, and such increasing capacity.
This is (in theory) the fastest raid setup.
No real limit to size. Apart from what your OS can address(close to 12TB on 32bit OS)
But there is absolutely NO SAFETY or fault tolerance. one disk dies, your entire raid dies, and the data stored on it as well.
(and believe me, restoring such data is EXPENSIVE)
RAID 1 Mirrors minimum two disk.
Write speed is quite slow. Read speeds are average.
Fault tolerance is one disk may die and data is still intact.
If more than two disks are mirrored, fault tolerance increases.
But capacity is limited to only one disk.
RAID 0+1 are combinations of striping and mirroring. Increased speeds and capacity.
And maintaining some degree of fault tolerance.
This setup is mostly limited to 4 disks. (more than 4 disks makes it VERY uneconomical)
RAID 5 same as RAID 0, but with certain advantages.
It needs at least 3 disks and it uses one disk for parity. Fault tolerance is one disk.
However if you are planing on running it with more than 10 disks consider RAID 6 instead.
RAID 6 same as RAID 5 but with two parity disks instead of only one.
Useless on raids with few disks. but becomes mandatory on large raids.
It will withstand a fault of two disks failing simultaneously.
Great when running a raid of 16 disks.
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After doing some testing. (on PATA and SATA disks)
Raid 0 and 5 increases speeds significantly until four or five disks are reached. But are sometimes maxed out at two or tree disks.
RAID 0 is by far the fastest raid configuration. (but it has NO fault tolerance)
Speed is limited by:
Average seek time, disk cache, internal transfer speeds, bus speeds, controller cache, internal controller speeds....
By raiding two 220MB/sec SSD disks read speeds of 400 MB/sec can be achieved.
But don't expect miracles from ordinary disks. 150 - 200 MB/sec can be achieved...
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To cut things short.
If you need speed and don't care about fault tolerances. RAID 0 is your thing.
If safety comes first, RAID 5 is recommended.
If you like me are completely paranoid by disk failure. Then RAID 6 is mandatory.
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As for RAID 0/1/0+1 (mirroring). i don't see no real use...
Striping two disks and then mirroring them with two more disks... it just wastes one disk and it will only tolerate one disk failure. (unless both disks of the mirror or stripe fails at the same time.)
By using RAID 6 and the same four disks.
still only two of them will represent the available storage. But it will withstand a two disk failure. maximum safety.
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EDIT: Adding a link to wikipedia article about RAID: http://en.wikipedia.org/wiki/RAID
EDIT: Correcting some facts.
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I've had a lot of luck with Raid 1 and Raid 0+1. In every instance where I've had a drive corruption, I've been able to recover from the good drive.
I'd highly recommend these two methods.
The risky Raid setup is Raid 0. Your actually doubling the change of losing your drive info. Should either drive fail, you're done.
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The best bang for the buck for multiple drives is to get a HighPoint eSATA RAID card. The 622 is a two eSATA port card that can use up to 10 drives, and the 644 or 2314 has four ports and can use up to 20. eSATA port multiplier enclosures are not horribly expensive. A Sans Digital five bay enclosure, for instance, is around $200 USD from NewEgg.
RAID-0 (sic) shouldn't even be discussed. It's not RAID since R in RAID stands for redundant, and striping drives makes things less safe than keeping them on a single drive. (Is there such a thing as negative redundancy?)
The simplest RAID setup is simple mirroring. Most x86 motherboards support BIOS-based mirroring. I'm not sure whether Windows has software mirroring, but just about any Unix-like OS (BSD, OS X, GNU/Linux) has software-based mirroring. You can also buy hardware-based mirroring enclosures which appear as one drive to OSes which don't have support (such as AmigaDOS).
If you're worried about viruses, then that implies you're using Windows. There's nothing RAID can do that can save you from that. Your only option then is to maintain two copies of everything, which is what others have said above.
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Check this list out, its a bit out of date but useful, avoid anything that says "fake raid", i.e its hardware tied software raid.
http://linuxmafia.com/faq/Hardware/sata.html
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Small clarification: (RAID 1+0) Faster than RAID5 when writing. Reading is pretty much the same.
Reading will be much faster than RAID5 with more than one application accessing different areas of the drive. The OS or RAID card will monitor the last LBA of each pair and target the closest pair. This greatly reduces seek time.
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Thanks.
An Article I was reading said that the user should have Backup Storage in case of a raid failure.
It also said ( or another post ) that cost wise that Raid 1+0 was better than Raid5 on the second disk failure.
For a newbie, it looks like the Holy Grail, when it fails it becomes a Holy Cow. :)
The board I want to get has 6Gbs SATA. How can I push that to the limit?
Do I need SSD's or many HD's?
Can a raid system beat the bloat? :)
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The best bang for the buck for multiple drives is to get a HighPoint eSATA RAID card. The 622 is a two eSATA port card that can use up to 10 drives, and the 644 or 2314 has four ports and can use up to 20. eSATA port multiplier enclosures are not horribly expensive. A Sans Digital five bay enclosure, for instance, is around $200 USD from NewEgg.
This description sounds like JBOD (just a bunch of disks) and is NOT in any way a raid. It is an array, yes. and will set any disk of any size into an array of ONE logic drive. However. if one disk fails... ALL data is lost...
i have tried it!!!
(linux and LVM may rescue your back...)
(unless you mount the drives as separate drives...)
RAID-0 (sic) shouldn't even be discussed. It's not RAID since R in RAID stands for redundant, and striping drives makes things less safe than keeping them on a single drive. (Is there such a thing as negative redundancy?)
Raid 0, or striping is performance wise the fastest setup.
It is good for, lets say. striping two disks as SYSTEM disks.
IF you are cautious about your placement of files you have no real loss if one drive fails.
Or you could set up multiple drives in raid 0, as a master drive for video editing. Recording the master to that drive before packing it and burning it to BD disks or moving it to your raid 5 for storage.
Raid 0 suits the needs of a fast drive to handle drive intensive operations.
And always remember to back up files.
The simplest RAID setup is simple mirroring. Most x86 motherboards support BIOS-based mirroring. I'm not sure whether Windows has software mirroring, but just about any Unix-like OS (BSD, OS X, GNU/Linux) has software-based mirroring. You can also buy hardware-based mirroring enclosures which appear as one drive to OSes which don't have support (such as AmigaDOS).
Yes and no... Striping two disks is as well easy. (unless safety if your goal) And gives a great speed increase.
However, i would stay clear of ANY motherboard raid controllers.
If you move to a new motherboard or it in worst case scenario fails...
You have no guaranties you will be able to restore your raid.
ALWAYS use separate controllers. They will also give a speed benefit since they remove disk operations from the CPU!
IMHO stay the hell clear of any software based raids. if you loose the raid table (which is very easy if your OS fails or crashes during write ops..) you loose the entire raid and all data stored.
I have tried it to
If you're worried about viruses, then that implies you're using Windows. There's nothing RAID can do that can save you from that. Your only option then is to maintain two copies of everything, which is what others have said above.
What about a anti virus software?
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Thanks.
An Article I was reading said that the user should have Backup Storage in case of a raid failure.
It also said ( or another post ) that cost wise that Raid 1+0 was better than Raid5 on the second disk failure.
For a newbie, it looks like the Holy Grail, when it fails it becomes a Holy Cow. :)
The board I want to get has 6Gbs SATA. How can I push that to the limit?
Do I need SSD's or many HD's?
Can a raid system beat the bloat? :)
I am not going to argue. but i would never use motherboard controllers for raid. especially if speed is an issue.
Dedicated controllers will remove a great deal of disk operation from the cpu.
And you have fall back, in case motherboard fails.
I have never had speed problems like piru og alexh explains when multiple computers access my server.
network has been the bottleneck then, even gigabit...
(for a HOME network!)
I would any day choose RAID 5 or 6 and a dedicated controller. My humble opinion though...
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How about the Raid 1+0 or I hear it is also called Raid10.
|| = mirror
+ = stripe
[ a || a' ] + [ b || b' ] + [ c || c' ]
I do not think you have to replace the whole set if you loose one.
1. I want to make win7 or win sever run faster.
2. I want to make Linux run faster? (ubuntu, fedora, slackware )
3. I want to edit movies with Blender.
4. I want to edit moves with Sony Vegas Pro 9.
I plan to add a 1TB drive for back up.
Thanks.
Extra:
SATA
5 SATA 6 Gb/s ports by AMD® SB850
1 E-SATA port by AMD® SB850
RAID
SATA 1~5 support RAID 0/ 1/ 10/ 5 mode by AMD® SB850
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I am planning to build a new computer and I wanted to get some advice on Raid5 and Raid 1+0.
I don't think anyone has asked this question of you yet ... but what are you wanting to use the storage for ?
Operating System ?
Personal documents and photos that are irreplaceable you can never afford to lose ?
Music/video/pron collection ?
Corporate filesystem ?
Database ?
Scratch disk for video editing work ?
Depending on what you want depends on the configuration of the underlying disk.
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How about the Raid 1+0 or I hear it is also called Raid10.
|| = mirror
+ = stripe
[ a || a' ] + [ b || b' ] + [ c || c' ]
I do not think you have to replace the whole set if you loose one.
1. I want to make win7 or win sever run faster.
2. I want to make Linux run faster? (ubuntu, fedora, slackware )
3. I want to edit movies with Blender.
4. I want to edit moves with Sony Vegas Pro 9.
I plan to add a 1TB drive for back up.
Thanks.
Extra:
SATA
5 SATA 6 Gb/s ports by AMD® SB850
1 E-SATA port by AMD® SB850
RAID
SATA 1~5 support RAID 0/ 1/ 10/ 5 mode by AMD® SB850
RAID 1+0 10 or what ever.
[ a1 || a2 ] + [ b1 || b2 ] + [ c1 || c2 ] - Disks A1 and A2 are striped together as goes for B1/2 and C1/2.. array A is "master" and array B and C mirrors A. Adding more mirrors will NOT increase capacity.
(you can of course expand with A3, B3 and C3. increasing overall capacity. but consuming tree more disks.)
That setup consumes 6 disks, and will survive a up to two disk failure.
OTOH
RAID 6 requires a minimum of four disk and will use two disks for parity.
Hower it will survide up to two disk failure. And by merging more disks you will increase overall storage. And maintaining two disk failure.
Like i have said before. i see no real reason to use mirroring!
To run OS faster, stripe two SSD disks together on motherboard controller. And use ONLY system on that controller. My friend has reached read speeds of over 400MB/sec doing so!
As for speeds... on a private home network you will rarely use the max drive speeds.
I have raided 6 120gig PATA disks, alone they are slow as hell.. but in a raid they are lightning fast. And i never saw anything to evidence speed penalties.
If you want os to run faster.. buy yourself a hyperdrive V5!
Or even raid multiple hyperdrive 5... :D
http://www.hyperossystems.co.uk/
(but now we are getting seriously expensive!!!)
Or upgrade RAM or/and CPU....
Move editing: while working on files: RAID 0. For storing files: RAID 5 or 6... MHO
I use vegas video 4 (predecessor to sony vegas 9) whit a similar setup.. Disk speed was never an issue.. CPU AND RAM is!
Get a dual Xeon HT quad core 64gig ram and Nvidia Quadro... That will render movies a bit faster.
Backup is NEVER underestimated...
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I found another nice step by step guide for you on how to setup a Home Fileserver using ZFS: http://breden.org.uk/2008/03/02/a-home-fileserver-using-zfs/
Take a special look at the chapters 2 and 3 where the author compares the existing products and explains why ZFS is the best solution nowadays.
If you want to be serious forget RAID (mainly on Windows)... :)
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Another thing to look at for the ZFS fetishists... http://www.nexentastor.org/
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I have a Silicon Image 3112 card, with two SATA 200gb drives in RAID 1.
One of the disks died and I was able to get my data off the other disk. When I replaced the mobo, I carried on using the card and drive, no problems.
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This isn't exactly on topic but I use an SSD for my boot/OS/programs drive and a RAID1 array for my precious data/Steam/Games/Videos/Music/etc.
It works pretty well, although I'm using the Intel fake-raid.
The SSD was the best upgrade I've ever bought though, screw the RAID array, get an external HDD to backup to and grab yourself a _good_ SSD for your boot drive.
Hell if you can afford it go for one of these:
http://www.anandtech.com/show/3788/oczs-revodrive-pcie-ssd-preview-an-affordable-pcie-ssd
:)
Andy
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This isn't exactly on topic but I use an SSD for my boot/OS/programs drive and a RAID1 array for my precious data/Steam/Games/Videos/Music/etc.
It works pretty well, although I'm using the Intel fake-raid.
The SSD was the best upgrade I've ever bought though, screw the RAID array, get an external HDD to backup to and grab yourself a _good_ SSD for your boot drive.
Hell if you can afford it go for one of these:
http://www.anandtech.com/show/3788/oczs-revodrive-pcie-ssd-preview-an-affordable-pcie-ssd
:)
Andy
SSD drives are dying even faster than conventional HDDs...
no safety in using SSD drives. SSD gives grater speeds...
Only secure backup media i know are tapes or CD/DVD/BD....
(even they have a limited lifetime)
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Double post \o/
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What's so safe with tapes?
I have had more trouble with tape than with all other media combined.
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What's so safe with tapes?
I have had more trouble with tape than with all other media combined.
Redunancy, for the most part. If you've got a different tape for every day of the week, if one decides to give you problems, go back one more day.
Not that I've had any reliability issues with SuperDLT tapes... probably should look into a new set though, these are getting old..
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This description sounds like JBOD (just a bunch of disks) and is NOT in any way a raid. It is an array, yes. and will set any disk of any size into an array of ONE logic drive. However. if one disk fails... ALL data is lost...
i have tried it!!!
(linux and LVM may rescue your back...)
(unless you mount the drives as separate drives...)
No, the cards I posted all do hardware-based RAID-5. (I did mention that they're RAID cards.)
Raid 0, or striping is performance wise the fastest setup.
It is good for, lets say. striping two disks as SYSTEM disks.
IF you are cautious about your placement of files you have no real loss if one drive fails.
There are no benefits of AID-0 (not RAID) which can survive data loss. The only way it's even possible to recover data from an AID-0 setup is if you set up two disks as a concatenated set and the filesystem supports growing, but doesn't yet grow to the second drive, meaning it's worthless to even consider such a setup. Failure of any drive in AID-0, for all practical purposes, means loss of all data.
Or you could set up multiple drives in raid 0, as a master drive for video editing. Recording the master to that drive before packing it and burning it to BD disks or moving it to your raid 5 for storage.
Raid 0 suits the needs of a fast drive to handle drive intensive operations.
And always remember to back up files.
AID-0 is no faster at lots of small I/O than RAID-1 or RAID-5 since you're still waiting for the mechanical movement of heads and you're still waiting for the average rotational latency period. AID-0 is faster for streaming contiguous files faster, though.
Without redundancy, though, it's pretty much worthless these days since even the inexpensive HighPoint cards I mentioned can do uncompressed full 1080 resolution high definition video with RAID-5.
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I just had my first HDD failure with the RAID-5. One of the 1.5TB Barraducas (ST31500541AS) dropped dead. I've swapped the drive and added the new HDD to the array with:
sudo mdadm /dev/md0 --add /dev/sdh1The raid is now rebuilding itself:
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdh1[3] sdb1[0] sdg1[2]
2930276864 blocks level 5, 128k chunk, algorithm 2 [3/2] [U_U]
[=>...................] recovery = 8.0% (117313844/1465138432) finish=516.8min speed=43460K/sec
unused devices:
This is the critical part. If the rebuilding fails due to failure in the remaining good drives I will lose the array and all data within. If it was RAID-6 I could still lose a 2nd disk without data loss.
Obviously I've backed up all important data before the rebuild, so only some less important data would be lost if 2nd disk failure should occur.
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Raid doesn't guarantee your data integrity. It doesn't detect silent data corruption for instance.
At present the best solution to preserve your data is to use ZFS as filesystem.
What about ReiserFS - I heard is was a killer filesystem.
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What about ReiserFS - I heard is was a killer filesystem.
That's funny... but it really shouldn't be
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Thanks.
An Article I was reading said that the user should have Backup Storage in case of a raid failure.
It also said ( or another post ) that cost wise that Raid 1+0 was better than Raid5 on the second disk failure.
For a newbie, it looks like the Holy Grail, when it fails it becomes a Holy Cow. :)
The board I want to get has 6Gbs SATA. How can I push that to the limit?
Do I need SSD's or many HD's?
Can a raid system beat the bloat? :)
I remember this review when I last upgraded in 2007.
http://www.tomshardware.com/reviews/cheap-raid-ravages-wd-raptor,1562.html
Using 2 raptors 0+1 was pretty impressive. And still is..
@sknight, ZFS ? Ur kidding me. With ZFS (pooled) you don't know the impact of a drive failure as you dont know which drive has which data. Very handy. Thats why Symantec(Veritas) make so much money on Sun.
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What about ReiserFS - I heard is was a killer filesystem.
AFAIK Reiser FS doesn't have all the benefits of ZFS. BTR is the only filesystem with the same ZFS characteristics but it's not ready yet (or better saying, tested enough).
As for the killer filesystem statement, that's the explanation:
http://www.theregister.co.uk/2008/07/08/body_found_reiser/
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@sknight, ZFS ? Ur kidding me. With ZFS (pooled) you don't know the impact of a drive failure as you dont know which drive has which data. Very handy. Thats why Symantec(Veritas) make so much money on Sun.
No, you are kidding me! You don't need to know where your data is. You just need to know which drive has a failure in order to replace it... ZFS shows clearly which drive has checksum errors. Then you just need to replace the disk.
Take a look at this video: http://www.youtube.com/watch?v=QGIwg6ye1gE
Two drives are literally destroyed during a live demonstration with no data loss. Try that with RAID-5! :-)
This video is very interesting too and shows how zfs detects silent data corruption (something that RAID doesn't!!!):
http://hub.opensolaris.org/bin/view/Community+Group+zfs/selfheal
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And there I was ready to share my River Raid playing tips.
Misleading subject. Bah
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lol
I have not seen RiverRaid in a long time.
I am not really settled on which Raid to use.
I will have to try both Raid5 and Raid 1+0 some day.
Raid! as the bug spray commercial goes.
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I'm running Raid 0 with an external drive for backup. They are both Seagate 7200RPM drives and the speed is between 200-243 MB/s both reading and writing.
The biggest plus is that it removes (lessens) the hard drive bottle neck. Anything writing to the hard drive has less time to wait.
If you want serious speed go for 2 SSDs (or 4 for 0+1) that will eliminate the long seek times as well.