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Need help choose either RAID 1 or RAID 5

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  • NAS / RAID
  • Backup
  • Performance
  • Storage
Last response: in Storage
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December 13, 2008 12:19:30 AM

HI im just getting my NAS Thecus NS3200PRO and i have 3 (1T) Identical Harddrive

but i need to decide eithr im going with RAID 1 or Raid 5 or JBOD?

WHat im using for this box is to backup all my data's

I read some article that RAID 5 will have slow performance isn't true? compare to raid 1 (mirroring)

what i need to know is what is the different between those 2 , please explain in simple english :) 

also if i go with RAID 5 it has feature called STRIPE SIZE from 64k ~ 4096K (what is this stripe for)

im novice on this raid thing i would hope someone can help me decide and explain what is different between those 2 raid or JBOD

thank you

More about : choose raid raid

December 13, 2008 1:26:04 AM

RAID is a complicated piece of technology. If you're using it please make sure you read about the basics. Wikipedia might help but RAID primers can be found all over the web.

RAID5 is much more complicated than RAID1. Notice that RAID1 with 3 drives is not possible; you'd need 4 or 2. Remember with RAID1 each drive keeps a copy of the other drive; so you must have an even number of drives.

RAID0 and RAID5 do not have this limitation. RAID5 allows you to use more space for storage. If you have 4 disks you can make:

- RAID0 with 4 disks: 4TB (count all drives)
- RAID1 or RAID10 with 4 disks: 2TB (50%)
- RAID5: 3TB (number of drives minus 1)

So RAID5 leaves you with more space, but its much more complicated and a bad implementation might cause you to loose data. So be careful when usign this option. The stripesize controls the performance characteristics of the volume, and is often set to 64KiB or 128KiB.
December 13, 2008 1:49:15 AM

HI i have this box called thecus n3200PRo basicly all i need just select the raid and it will configure for me

but i need to know the performance wise? raid 1 or 5 is better (which one faster)

from what you told me that raid will will be able to access those 3TB harddrive i have isn't (*that is way raid 5 have more spaces) which in raid 1 mirror will copy exact if i have 2TB i will only use 1 TB , the other is mirror

How does Raid 5 face fault tolerance, what i mean is in RAID 1 if one drive fail , the other drive take over

in raid 5 how does it work? will do similiar thing or what

please explain to me , sorry but im starting to get clear picture ,

thanks for your explanation its really helpful but if you can answer my questions on this i will get even more clear picture

a c 84 G Storage
December 13, 2008 2:03:17 AM

Since you have 3 disks, your only option is RAID5 and isn't necessarily slow (it's used a lot in enterprise servers) and it certainly isn't complex. RAID1 would be faster for writes, but usually disks are read a lot more than they are written to. What will you use it for? That can dictate the RAID5 stripe size, but usually the default works fine.
December 13, 2008 2:06:51 AM

Yes i read more than write to the disk

help me to understand one thing, if im using raid 5 from (3 TB ) harddrive i have, how much space can i access, can i access those full 3 TB or only 50% of it whic is 1.5 TB

also how does Raid 5 backup the data( i mean like raid 1 its mirroring) does raid 5 the same too?

thanks
a c 84 G Storage
December 13, 2008 2:22:22 AM

If you have 3 1TB drives, 2TB will be available for storage. RAID5 requires at least 3 disks and you always lose the equivalent of one disk. RAID1 is a bit safer, but the risks with a 3 disk RAID5 are not much higher. If a disk goes bad, you need to replace it right away, wether you use RAID1 or RAID5.

If you had a large RAID5 with a dozen disks, then the risk of having 2 drives go bad at the same time would be significantly higher. No RAID type is a backup solution - you still require a backup solution if you're going to store important data.
December 13, 2008 2:36:21 AM

If im using raid 5 now, what is the stripesize control should i use
64KiB or 128KiB or higher and what is the purpose of this i saw there is 4096

can u explain to me

btw ghislaing , thank you so much for your explanation and patient
a c 84 G Storage
December 13, 2008 2:52:44 AM

64KB should be fine. If you read and write large files sequentially, then use 128KB or larger. A larger stripesize usually doesn't provide marked benefits, but then again it depends on what you'll use that RAID for.
December 13, 2008 3:25:05 AM

Heya,

Google/Wiki what RAID actually is before thinking you actually need it. And even then, again, read what it is before you actually post about it and ask something that you could have easily answered. Someone can post and say what RAID1 vs. RAID5 is, but if you have no concept of RAID in the first place, what good is that? And if you're trying to trust your data to something you just read on the internet without actually investigating it thoroughly, don't come crying when you ask what happened to it all when you lose it.

Seriously.

Google RAID and read.

And I don't mean to sound like a total internet douche or something; it's just that RAID is both simple and complex at the same time. It's not something you just jump on and spend hundreds of dollars into unless you already know what you're getting into and the risks involved.

RAID1 is for making clones of data. This is not good for `backups' unless the clones are removed and replaced periodically.

RAID5 is for uptime of data. This means, if a failure occurs, the array is not dropped, remains up, and you can recover without even shutting down. This is not a good `backup' at all. It's an `uptime' tool.

RAID is not good for backing up data. RAID is all about essentially gathering speed, increasing capacity via using several disks together, or generating uptime due to fault tolerance or redundancy. Backup is something you don't use something like a HDD for. Backup is done with tapes, optical media, online remote hosts, etc.

Consider what you're trying to backup. If it's your porn collection, pirated MP3's, and some games you've downloaded, you don't need RAID at all. Just let the disks be separate disks, and if you want to save any of it from potential loss, burn it to DVD9. If it's actual data that you simply can't lose, like financial information, business related information, work information (like digital media that you actually work with), then RAID is also not good, as it will fail eventually and again you should seek another method of backup.

NAS is basically good for sharing light streaming to multiple clients without each client needing to have a copy of the data source. At home, this is good for sharing media, like music, etc. At the office, if combined with far better backup measures, it's a good way for everyone to use lighter terminals to access the same data rather than each system be separate (and thus makes backups much easier too).

Granted, it's none of our business what you are `backing up' or `serving' through your intended NAS; but hey, food for thought.

You're likely better off just taking a machine, putting some drives in it, setting up FREENAS and not bothering with RAID. Burn important stuff to DVD9 and call it a day.

Very best,
December 13, 2008 5:03:48 AM

hardwarefish said:
HI im just getting my NAS Thecus NS3200PRO and i have 3 (1T) Identical Harddrive

but i need to decide eithr im going with RAID 1 or Raid 5 or JBOD?

WHat im using for this box is to backup all my data's

I read some article that RAID 5 will have slow performance isn't true? compare to raid 1 (mirroring)

what i need to know is what is the different between those 2 , please explain in simple english :) 

also if i go with RAID 5 it has feature called STRIPE SIZE from 64k ~ 4096K (what is this stripe for)

im novice on this raid thing i would hope someone can help me decide and explain what is different between those 2 raid or JBOD

thank you


Raid 1 is a mirrored copy of whatever you put on it. By this, I mean both (in your case) drives will have the same set of files that you copied over to it. It will be somewhat faster than raid 5, at the expense of lost space. You lose half of the space of however many drives you put into the mirror. Recovery of a drive dying is fairly straightforward, just break the mirror (if it still exists) replace the drive and create a new mirror set. This re-mirroring process will take quite a while, and depending on what processor / OS Thecus uses, you may or not have access to the data while it is processing. It will be slower access, if at all.

Raid 5 is a striped set of whatever you copy into the raid set, with each pair of drives having enough information to rebuild the set in case of failure of one member of the set. (I'd get into the algorithms used, but it is a bit complex) It is just as safe as a mirrored set, but will allow read / write access during the rebuild. Depending on your application, and the quality of the processor / OS, users might not even notice the speed difference. Look at the average file size of what you want to copy, that will give you optimum stripe size configuration. If you set stripe size too high, say 128k, and you are copying small files, each file will take 128k of drive space. This might lead to less data on the raid set than you planned for. Too small, say 4096 bytes, and each file will take a lot of time to copy over as it will reside in many stripes. Most people find that 64k is an ideal compromise. I do know one photographer that uses a stripe of one M....

JBOD is just what the acronym suggests, its 'just a bunch of disks'. ie, three drives, you will need three drive letters or three shares. If a drive fails, too bad.

Hope this helps somewhat...
December 13, 2008 5:08:15 AM

Croc, thanks a lot for the information that its helped a lot

so if you were , which RAID are u using to save data and website. becuase i have over 400 websites and each website have quite some DB and static URL which generated by the DB

also a lot of files like doc, excel and also music and pictures

but the most important the website, becase i keep having more websites

thanks
December 13, 2008 5:27:11 AM

hardwarefish said:
Croc, thanks a lot for the information that its helped a lot

so if you were , which RAID are u using to save data and website. becuase i have over 400 websites and each website have quite some DB and static URL which generated by the DB

also a lot of files like doc, excel and also music and pictures

but the most important the website, becase i keep having more websites

thanks


Personally, I use raid 5. I appreciated it after a drive failure, as I barely noticed. In your case, for stripe size, don't know. Most websites are just a collection of small files, (ie not properly optimized) and your doc and excel files will be at the other end of the spectrum. You will be the best judge of this, but at a guess I'd look at 32k or possibly 16k.
December 13, 2008 5:29:08 AM

HI croc what do you mean by "I Appreciate it after a drive failure" have you used Raid 1 and fail on you that is way you said that or you use RAID 5 and fail on you

which is the case and when it fail it does not let you know? so RAID 5 will notify you if the drive is fail?

thanks
December 13, 2008 6:12:59 AM

hardwarefish said:
HI croc what do you mean by "I Appreciate it after a drive failure" have you used Raid 1 and fail on you that is way you said that or you use RAID 5 and fail on you

which is the case and when it fail it does not let you know? so RAID 5 will notify you if the drive is fail?

thanks


Oh... OK, I started my personal raid (a readynas 600) with two drives in raid 1. One of the drives failed, and I bought another. Rebuilding the array took literally days, during which I could read slowly, but was blocked from writing. Meantime, I did diags on the failed drive, did a repair, and copied the last drive in the old mirror to the refreshed drive. So I decided to re-do the array in raid 5, using three drives. I took the two new drives, built a raid 5 array, copied the old data over... (Acronis is a valuable tool, BTW.) Then I decided that the old drive was 'good to go' now, so I added it to the array as well. Needless to say, 'good to go' drive again failed. I RMA'd it, but never noticed a difference in read speed and write speed was only 'somewhat' slower. Once the RMA'd drive was returned, I again added it into the array, but never really noticed any speed difference in reads or writes.

My purpose was to take all of my CDs and make copies that could be streamed to my media player in the lounge. As projects go, it took over a year of spare time and a lot of experimentation, but I now have a CD collection that can be easily accessed, wil play over my home theater system, and is well catalogued. But my array is now too small....
December 13, 2008 6:28:40 AM

Croc, so you did not notice any differences between raid 1 and raid 5 from your personal experience.

btw what is the stripe should i use then 64k or 128k since i told you what im going to use this box for?

btw how is your radynas600, is it good?
December 13, 2008 6:46:09 AM

Croc or anyone else in this forum , i have confusion here about raid 1

everyone said that raid1 only used 2 disks right but when i build my raid with Thecus N3200PRO

it have 3 Disks , then i check 3 of them then i build raid 1

it seems that it took those 3 disks. check the url :www.angryplastic.net for the screenshot .

Does this mean that the raid 1 only still used 2 disks intead of 3 disks (so it will ignore 1 disk) even i build 3 of them for raid 1

but if that is the case why this box n3200pro make it seems that this 3 drives working as raid 1

please expalin to me

thanks

December 13, 2008 6:51:14 AM

hardwarefish said:
Croc, so you did not notice any differences between raid 1 and raid 5 from your personal experience.

btw what is the stripe should i use then 64k or 128k since i told you what im going to use this box for?

btw how is your radynas600, is it good?


I never had a chance to do an apples to apples comparison back then, but can say that writes 'seemed' faster with a mirror than a striped array. As it would, it is really just writing to the mirror's master not the whole array....

As I said previously you might be better served with smaller stripe size than most given that most of your files will be website information. Only you, in the end, can determine the right size as only you will know the size of the majority of your files. Or your uses, for that matter. If I were doing my array over, I'd use a 1024m stripe size... Who knew how much space a loss-less codec would take? But in day-to-day practice, I really don't notice any speed issues.

As to my wee array, I'd get a better model now (and may) as mine is not hot-swappable. Other than that, the software and support are supurb for a SOHO provider.
a b G Storage
December 13, 2008 10:38:02 AM

RAID is not, nor was it ever meant to be a backup.
Drives fail, controllers fail and I don't care if you use RAID 1 or 10, you data can be lost in an instant. RAID was designed for maximum up-time, and throughput.
December 14, 2008 10:46:12 PM

simple answer for the guy.

I like the backup of raid 1 because the rebuild is faster and you won't notice much of a performance hit as you would in raid 5 instead of raid 5 but in your case raid 5 would better suit you because you have 3 drives but the rebuild time takes FOREVER im pretty sure if you ever had to rebuild raid 5 it would take a day easily.......

over all my years the only data i have lost was in raid 0 arrays... never lost anything in raid 1,5,10.

most annoying raid array was : 5

best raid array i use : 10 or 1

for a while i used 4x 500 GB hdd's and put em in raid 10... never had any failures because failures RARELY happen... especially in raid 10. as to the controller failing... I had that happen before and i didn't lose any data.... maybe im lucky...

the only thing i really backup is pictures even though i don't have to since 2 drives failing at the same time is... VERY unlikely...
a c 84 G Storage
December 14, 2008 10:56:15 PM

I've been using RAID for a long time and I don't totally agree with you that RAID5 will take forever to rebuild. I've swapped defective hard disks in RAID1, RAID5 and other types of RAID on servers, SANs and NAS' and it never took a day to rebuild an array. It will be slow only if the array is very busy and rebuild is set to low priority. With a dedicated array, rebuilding time shouldn't be an issue.
December 14, 2008 11:09:52 PM

so that's what life without a dedicated raid controller is like... very nice. I have heard raid 5 is much better with a dedicated controller for it.

if it isn't busy its about 8-10 hours for me if its busy it will take a day.
December 15, 2008 12:13:21 AM

Im convince now with Raid 5 performance no much different than Raid1

I test it myself. But for safety wise which are better

if i have 3 Harddrive with Raid 1 , 2 will be mirror and the next one will be HOT SPARE (which the tech people in Thecus Said, means the other drive will be ready to take over incase one of them failed), its look like there are double safety

But in Raid 5 , one drive fail i will not lost anything unless 2 drives fail at the same time

December 15, 2008 2:04:15 AM

raid 5 and raid 1 performance are like apples and oranges...

try installing a operating system on raid 5 and you will notice the performance hits.

what are you going to be using the raid for? that will give us an idea so we can give you the correct answer.
a c 84 G Storage
December 15, 2008 3:17:48 PM

The Thecus NS3200PRO has a dedicated RAID controller, therefore RAID5 shouldn't really be slower than RAID1. Installing an OS is mostly writes to the disk. On the other hand, files stored on a disk usually are read more often than they are written. RAID5 is quite good when reading back and that's why it's often used in corporate environments.
December 15, 2008 5:01:48 PM

ghislaing, Yes im using this N3200PRo for files stored and i read more then write.

So i guess im good with RAID 5 then.
a c 84 G Storage
December 15, 2008 11:40:35 PM

I'd go with RAID5. Just in case, always backup files that you can't or don't want to lose.
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