Raid From 6 Disks - What Mode Is Best?

[Giniu 0]

Hi,I have small question - wonder if someone would be able to give me some hint... friend of mine have 6 SATA II Raid-ready drives (longer waranty and hot-plugable)... he cannot have more - all are same vendor, size, and almost serial number as they came in box packed together... just to plug in...It would be used mainly for securing his programming environment so lot's of small files (also whole system built from source, and general file backups), there would be RaiserFS 4 on disk with 4kb node size so small files would be happy. There wouldn't be too big files, few movies recorded on fly but no file would exceed 1GB... (this makes such big cannon like XFS not best choice and that's why Raiser was choosen - also for it's long known stability)...now - he decided he want to build Raid matrix... and already have 6 drives but isn't able to plug more on his hardware. It for sure is about data security so it should be mixed method and include Raid 1, but still should be faster than working on one disk.So... raid 10? Or maybe 0+1 or not with 1 - something like 30, 50?... if there would be 8 disks there could be used raid 100, but there are only 6...so... anyone have some recommendation?\Gps.: first thread after soooo long ... almost forgots how it feels

Edited September 5, 2006 by Giniu (see edit history)

[yordan 10]

You should better tell us the available modes on his device.I definitively say don't use raid0, because this means "no security, striping only".Raid1, raid 10, raid1+0 are not the best ones for personal or small buiseness use, because security costs 50% of the total disk space (this means that the 6-disk raid group available capacity will be the capacity of three single disks).If your disks have RAID5 mode, I suggest it's the best mode. A RAID5 group of 6 disk will will have the capacity of 5 real disks, and it will be reasonably secured because it will survive to the lost of one single disk, and will continue working (without any further security) until the faulty disk is repaired.So, first of all tell us which RAID types your device can use, mainly tell us if it can use RAID5 or RADI6.RegardsYordan

[Giniu 0]

About 5 then it is supported... about 6 I would have to check to make sure but I don't think so.

[yordan 10]

So, I would say that, for your needs, a RAID5 group of 6 disks is the best one. It will provide you with a secured total disk capacity of five time the single disk capacity, and will be able to continue working in case of loss of one of the disks.In these case, the cost of security is : one disk.Also, have a look on your RAID specifications, and see if your system can provide a hot-spare.Then, you can alternatively create a five-disk RAID5 group and a hot-spare.In this case: the cost of security is : two disk.The advantage is : if you loose one disk, the missing disk is rebuilt on the hot-spare disk, and you are protected again, you could experience a second crash disk without loosing data.If you have no hot-spare disk possibility, the system continues working if a disk is missing, but you have no more protection until you repair the faulty disk.Tell me again if this is not clear enough.

[Giniu 0]

Sure it's clear, I know the way how raid levels work - just wanted to double check with opinions based rather on experience in that exact casethanks for your answer Yordan...\G

[wutske 0]

I hope he has a good RAID controller, because generaly, onboard RAID controllers are good for 0,1 and 10, but they are only good at RAID5 when it comes to read speeds. Onboard RAID5 causes a serious write-performance drop (even below the minimum speed of a single hdd) because they lack a good processor.Ow, and I hope he didn't buy those hdd especialy because they are hot-swapable, because every SATA disk drive can do that .

[yordan 10]

Ow, and I hope he didn't buy those hdd especialy because they are hot-swapable, because every SATA disk drive can do that

Of course, but only disks in a raid group can fail without loss of data. And, of course, the SATA disks you buy have to match the disks matching your raid adapter device.

[wutske 0]

You don't need a special set of HDD's in order to get a RAID array. The same brand and size is usualy enough to get a RAID-setup working. You can even combine different brands and size, but then you'll loose space.The extra warranty is a good thing anyway

[iGuest 3]

LARGE RAID 6 Raid From 6 Disks - What Mode Is Best?

We have just installed a MD1000 with 15-1TB disks and we need as much space as possible with the best possible protection. I have heard about RAID 6 in some small part, however, I don't know if this is the type of technology that would best suit our needs. I know, from RAID calculators, that instead of using RAID 5 with 4 VD and losing 1 disk per RAID group for parity as best practice, I could create one large RAID 16 with the 15 disks that I have losing, I think, 3 of them for parity and a hot spare. Any suggestions?...

Oh and I have used RAID 10 before and in a high I/O environment we did not seem much of an improvement over RAID5 and our disk space was halved by using RAID10, so my suggestion would be not to go with RAID10.

- Sarge

[iGuest 3]

6 HDD Bay with RAIDRaid From 6 Disks - What Mode Is Best?

I am looking for cost effective solution to attach 6 HDDs externaly on my PC. I should be able to use RAID 5 on these HDDs. Any one can suggest solution and availibility with any vendor.

Sunil

 

-question by Sunil Anaokar

[yordan 10]

I definitively stand for RAID5 if your device accepts it.RAID6 is more secure because it allows you loosing two disks without stopping, whereas RAID5 survives to the loss of only one disk.However, loosing two disks at the same time is almost impossible, so RAID5 is enough.

[turbopowerdmaxsteel 0]

I saw a 4TB HDD on ebay a few days ago. It was marked as RAID. Don't we need multiple Hard Disks slotted into a RAID controller to actually be called as RAID? Or could it be that this device has multiple 4TB drives inside it (seems kinda unbelievable to me)?

[turbopowerdmaxsteel 0]

I saw a 4TB HDD on ebay a few days ago. It was marked as RAID. Don't we need multiple Hard Disks slotted into a RAID controller to actually be called as RAID? Or could it be that this device has multiple 4TB drives inside it (seems kinda unbelievable to me)?

It seems like it is such a controller with 4 x 1 TB drives. If RAID is enabled, the total capacity of the drive drops. I would have bought this thing if if had RAID at 4 TB capacity.

 

My company requires a RAID arrangement for our CVS repositories & JIRA server. They were unable to find a RAID controller in the city. I will recommend this to them.

 

Which is the most optimum RAID configuration in terms of reliability, effective disk space & recovery from disk failure?

[yordan 10]

Which is the most optimum RAID configuration in terms of reliability, effective disk space & recovery from disk failure?

RAID5 is the optimum configuration. In terms of reliability, it continues working without any trouble after loosing a whole disk, without any disk failure seen from the computer side. In term of disk space, it costs one disk. This means you have 4 TB disk space with a RAID5 configuration on five 1TB disks. Depending from the vendor, the recovery has several levels of easiness.
If you buy an EMC disk cabinet, in case of disk failure, the faulted disk has a red light lit ; you simply grasp the faulty disk, you insert the new disk, and the disk recovery starts automatically and immediately. Unfortunately, the EMC disk cabinets are rather expensive.
Cheaper NAS solutions exist, but you have to read the manuals in order to understand : no disk failure but you have to do something in order to start repairing after faulted disk repair.
Regards
Yordan