DescentBB

So besides planning on upgrading my network with a gigabit Ethernet switch I'm also playing with the idea of upgrading my storage server and the general setup of it.

What I'm looking to accomplish is a huge storage server with a redundant fail-safe. I currently have 1.5TB capacity with no backup system.

The setup I'm considering is to build two identical systems. One as the data server and the other as the backup, setup similar to our office setup were the server will run a scheduled backup and save it to the second system. Unless someone has a better option for me I was planning on using the windows build in backup schedule feature. Further more I'm considering doing the storage upgrade over a stretch of time as the need for larger space is required and this will lighten the burden of spending a fortune on a heap loud of HDD's right now.

On the storage front I was thinking down the lines of running a small HDD just for the os and the adding 2TB HDD's over time and partitioning then as dynamic volumes and running them in a JBOD setup which will mean that with a motherboard that supports 6 sata drives I could end up with an effective 10TB of storage. This however brings me to one question. My operation systems will vary between win7 (x64), winxp & vista the last two being x32 os's. From what I could gather as far as my win7 systems goes it should not have any problems should the server space exceed 2TB but I'm not sure whether the 32bit os's will see the JBOD volume in total e.g.. 4 or 6TB once it will exceed 2TB as the max size I believe is limited to 2TB. Is this true for a volume over a network as well in an 32bit system? If this is true besides switching to a 64bit os is there another work around perhaps.

The reason I opting for a JBOD setup vs RAID is that I've never setup a raid array before and from what I understand some of the RAID arrays require a certain amount of drives and that they must be identical in size.

As I said it's the idea I'm playing with but still in the research phase and I'm open to suggestions.

Thanks

I'm not too familiar with JBOD, but from the limited research I did, it doesn't seem as conventional as RAID, and it doesn't support redundancy that I can see.

I'll explain the setup we are implementing here @ work. We have a system with 4x 1TB drivers on a mirrored RAID (2TB effective storage). That right there is a failsafe redundant solution.

Then, we have a Thecus 4100pro network box with 4x 2TB drives in it (4TB effective storage). Now we plan on using Backup Exec to back it up, but you could just run Norton Ghost or Windows Backup or something.

I sort of get what you are saying about RAID being in itself a redundant setup but correct me if I'm wrong. When RAID is setup in the redundant config it merely means the same data gets written on a number of HDD's e.g 2 or 3 depending on the setup and if one fails you have a backup.

The limitation with this thou is you are confined to the HDD's actual capacity e.g. 2TB and the other limitation without adding a addon card is the number of HDD connections on the motherboard.

JBOD is also a sort of RAID but where RAID requires the the HDD's be the same size JBOD does not and merely span the HDD's size as one volume. I know there is RAID config that also does this effectively making 3x2TB HDD = 6TB where the redundant config will merely be 3x2TB = 2TB. With the JBOD in theory you can mix up the size e.g. 2TB+1TB+1.5TB = 4.5TB.

The aim with the setup is to achieve a massive storage capacity at the end of the day together with a backup/redundant fail-safe and that is why I thought of the duplicate system as to copy the backup files to.

To compare, the Motherboard I'm looking at has 6x SATA2 ports in RAID and setup in redundant mode I'll only be able to max out at 4TB on the system. With the JBOD setup I'll be able to max it out to 10TB. Redundancy achieved by a scheduled auto backup to the second system.

Practically looking, with my intended setup I should be able to start out with only getting a 2TB drive for now and as the demand increase I can just redo the server by adding another 2TB or whatever size HDD restore the content from the backup system and then upgrade the backup system to match the main server size and re-backup. Now I do realize that would require a bit of coping every time but still cost wise it makes a bit more sense for me.

The drawback thou of my setup is the fact that I will require 2 PC's but will run in a box mode only as I only intend to remote control in on them after they are setup and I need to work on them so at least its minus the screens and k/b & mice.

But like I said I'm open to suggestions if my logic is flawed in some way

hmm sounds like it might work. I personally don't like the idea of spreading a volume across multiple HDD's - different seek times, etc.

In my opinion, I would rather purchase a RAID setup then spend the extra on having a separate PC.

When a RAID 5 loses a drive, you get a degraded raid but the data is safe. In a 3 drive configuration you get two times the capacity of the smallest drive. Example, 2x 2TB drives + 1x 1.5 TB drive would form a 3TB RAID5 array.

When a JBOD loses a drive, EVERYTHING goes with it.

Most RAID5 setups these days, including software have the option of expanding the array both by adding more drives, and by replacing the drives with larger ones.

Perhaps the most important thing to think about is that the more hard drives you have, the more likely you will experience a hard drive failure. From my experience as the number of drives someone has in arrays around the house approaches 10, the odds of one or more of them failing approaches infinity.

Uhmm okay I hear what you all are saying about the JBOD option in that if one drive goes belly up all is lost. And should a drive on each system fail however unlikely but possible you're basically up the creek without a paddle.

Now if I understand what I've read up quickly on RAID 5 on wiki:
1) the drives need not be equal in size?
2) the minimum discs required is 3 but the max is theoretically unlimited but of course only limited in as far as the number of SATA ports supported on the Motherboard
3) the equation is S(min) x (n-1) S(min) being the smallest drive size and n the number of drives, thus two e.g.
3x 2TB array = 4TB total size
4x 2TB array = 6TB total size
If these calculations are correct I'm thinking that a compromise of 2TB in total storage in RAID 5 vs a JBOD array with the same amount of drives is acceptable as you gain redundancy which JBOD lack.

But RAID still isn't a true replacement for a proper backup system, right? You will have redundancy if hardware fails but not in the event of software/viral whose which could leave data deleted or corrupted.

So a second system for Backup purposes instead of redundancy would still be advisable I think or any storage option maybe that would be able to store an equivalent amount of data that is on the server separately.

I also get what your saying, Krom, in that the likelihood of disc failure increases equivalent to the number of drives you're adding into the array, even wiki warns about this Thus leaving me to think that the better \"upgrade\" option down the line in a RAID 5 array isn't adding in more discs but rather replacing the current discs with larger capacity discs, I'm just a bit out of the loop as to whether the computer industry will exceed single 2TB drives for Joe public but do believe so.

But RAID still isn't a true replacement for a proper backup system, right? You will have redundancy if hardware fails but not in the event of software/viral whose which could leave data deleted or corrupted.

So a second system for Backup purposes instead of redundancy would still be advisable I think or any storage option maybe that would be able to store an equivalent amount of data that is on the server separately.

You are correct. RAID only protects hardware failure. You need another solution for when the user fails.

Something we did for a long time where I work is we have a linux box with a RAID setup. Every night, it would copy data into a tar.gz folder, and delete the last one that was a few days old. It was just a basic script.

FireFox wrote:I'm just a bit out of the loop as to whether the computer industry will exceed single 2TB drives for Joe public but do believe so.

http://www.newegg.com/Product/ProductLi ... 1&name=3TB

As for the other items, yeah you pretty much have the idea. RAID5 in particular is all about providing high uptime, not iron clad data protection. The best option is always to have a complete mirror of the data some place else that gets updated regularly.

Thank you Krom, good to know my instincts can still be right

Okay I think my overall setup idea has now been confirmed as a main system that will eventually run a RAID 5 and a second system as the backup also running RAID 5.

Now I just want to clarify some of the nitty gritty stuff I've came across in my research/expansion of knowledge.

NOTE: I know this might fall off the initial topic but feel it doesn't warrant a new topic and is still in a way relevant.

Firstly RAID, there seem to be a couple of ways to set it up, namely Firmware, Hardware, OS/Software. My question is which is best? PS I'm planning on running Win7 (x64) on the systems. Now not digging to deep into it yet it seems that Win 7 doesn't support RAID 5 (software wise) out of the box but can with some tinkering LINK
I'm guessing I'm answering my own question here as in it would be safer to go with a motherboard that supports RAID 5 in its BIOS?

Secondly HDD configurations. (This is assuming that I'll be going with a hardware RAID 5) I'll still be able to install a dedicated HDD for the OS and then the HDD's intended for the RAID config? The reason is I have two smaller size SATA2 HDD's (120gb & 250gb) I'd like to use to install the OS on for each system do have the OS independent and away from the RAID drives so to minimize possible issues with a OS crashing if I upgrade the RAID drives in the future and maximize the actual storage space for my server data as well as minimizing possible data loss due to a OS going bonkers.

Thirdly SATA3 vs SATA2? This is a bit off the topic but something I was wondering about.
First of it would seem that you can run a SATA2 HDD on a SATA3 port and vice versa obviously in the first instance you will only get SATA2 speeds then. I've found some contradicting responses on this question but on the law of averages the most people confirms that SATA2 and 3 is backwards compatible both ways?
Secondly which should I invest in getting SATA2 or SATA3? Currently the SATA3 is quite a bit more expensive from my supplier where I can get it at vs its SATA2 counterpart. This leaves me with the question of is there a significant gain in going SATA3 or not or will this be negated by the RAID 5 config or is the gain insignificant in real time application? Bare in mind the network will by then be a gigabit Ethernet but my other PC's are still running SATA2 drives and only my newest pc is capable of handling SATA3 (thou its running on a SATA2 at this time) as my other are pre SATA3 boards.

So if my logic is correct any gain of SATA3 will go out the window once I transfer data from a pc that is running with a SATA2 drive as it is limited at 3G/s and the only systems that will take advantage of the SATA3 is the Server and the Backup system up until I upgrade my other pc's to SATA3 which in all honestly I can't see happening anytime soon but maybe WAY down the line eventually on my current main gaming pc (this is the one that do support SATA3 but is running a SATA2). But then I should also consider that the Server is build for a long life span and will in all likelihood outlast any of my current main pc's

Software vs Hardware RAID both have their advantages and pitfalls.

With hardware RAID it typically uses fewer resources and so frees those up for the rest of the system to use, thus the overall system will be faster, but if the hardware breaks or you want to upgrade you have to find identical or compatible hardware to replace it. This means if you build a new computer your RAID might not be able to make the transition without rebuilding it for the new system and copying everything back on to it (which with 4-6 TB of data it would take a while). Also note that most on-board RAID chips are actually still software RAID and make the CPU do most of the work through the driver.

Pure software RAID has the portability advantage, just install the appropriate software in any computer or OS then connect the drives and it should work. Software RAID has a higher resource use (CPU time, memory, etc), but that also comes with a payoff since your CPU is typically faster than the embedded processors in true hardware RAIDs so a software RAID will actually be faster than an inexpensive hardware RAID, which is generally a surprise to most people. But remember the RAID is faster, however since it is using more resources the overall system will actually be slower as a result.

As for the SATA3 vs SATA2 question... The difference is completely irrelevant in the mechanical hard disk space. The fastest hard drives available currently barely break 120 MB/sec sequential transfer speeds, so even the ancient SATA1 (1.5 Gbits/sec) is fast enough to handle them without becoming a bottleneck. Basically SATA2 (3.0 Gbits/sec) is only just barely becoming useful for mechanical hard drives while SATA3 (6.0 Gbits/sec) is completely beyond them for at least another 5+ years, it is only for SSDs.

Great stuff, SATA2 it will be then as it is much more cost effective for what you get in the end.

At the moment I think I'm leaning towards a hardware RAID option meaning a motherboard that supports it. I'm still googleling these two options but this is going to be a dedicated system so portability and system resource usage both isn't that much of a factor I think. Currently hardware wise just seems to be the easier way to achieve RAID 5. But that could be because I've yet to find a decent article setting out how to setup a RAID 5 software wise in Windows 7 as you'll most likely need third party software to do this.

But I did notice some controversy of RAID 5 vs RAID 10. A lot of people are strongly opposed to RAID 5 suggesting RAID 10 instead. Their main argument boils down to the URE of SATA drives (SATA drives are commonly specified with an unrecoverable read error rate (URE) of 10^14). Stating that it has become much more likely that you will get a can't read URE in conjunction with a disk failure.

Any thoughts on this?

What I've gather so far is that RAID 10 is nothing else than 0 & 1 arrays working in conjunction with one another (spanning a pair of drives and mirroring them to the other pair). Obviously this entails you to have more drives in your array.

Bottom line the way I sum it up RAID 5 will achieve redundancy with less drives for the same amount of space than in a RAID 10 making it a bit cheaper with a bit more risk vs RAID 10. RAID 10 is also argued to be faster than RAID 5? If so how much is this in real time situations relevant/noticeable besides for the rebuild that I can obviously see a mirrored drive restoring faster than the parity system of RAID 5.

For me I think the main factor now will be costs leaning me to go RAID 5 for now making it cheaper as I can rather build a RAID 5 now requiring less drives and then later as I get more HDD's I can consider switching over to RAID 10. RAID 10's trade of is of course reduces overall space in relation to the amount of HDD's in the array.

RAID can get you faster speed, data redundancy or a balance of both - but it can never replace proper backups.

The question is this: do you want more speed or less downtime?

also, you lose space in RAID 5 due to parity data, RAID 10 won't, as its a a RAID 1 in a strip-set for speed.

you need 3 disks for RAID 5 minimum, 3 for RAID 10

fliptw wrote:The question is this: do you want more speed or less downtime?

Well lets put it this way, if everything is working 100% I'd like it to be fast but should there be something wrong I'd like a setup where downtime will be limited to the minimum so I'm guessing I'd settle on a little compromise on the speed to achieve that if need be.

fliptw wrote:also, you lose space in RAID 5 due to parity data, RAID 10 won't, as its a a RAID 1 in a strip-set for speed.

you need 3 disks for RAID 5 minimum, 3 for RAID 10

That's not the way I understand it.

A 3x 2TB array in RAID 5 will give you 4TB storage but you will need 4x 2TB in RAID 10 to get a total of 4TB so how can you say you loose space in a RAID 5. As I see it you need less drives in RAID 5 than in RAID 10 to achieve the same storage capacity.

And isn't the minimum discs for RAID 10 4 discs. See this RAID calculator I just came across LINK