Raid Disk

[inteificio]

I think smudge was just raising the subject as a consideration, not asking for help. Just incidentally - do you really know ALL about RAID arrays? Bold claim, but if you do you might be a useful reference point when we (our company) get stuck.

Ok I I will rephrase:
I know enough about RAID arrays to answer basic questions.
I could be of great use to your company though...I make good tea, can clean windows and if needs be I can be used as a VERY effective draught excluder.

Peter

 

[snowflake]

For the record

there are only three types of raid, microsofts incarnations are utter bollox...

There is

Raid 0 - no fault tolerance 5 x 200gb disks would give you a massive storage of 1tb, but if one disk goes your shafted.

Raid 1 - disk mirroring 2 X 250gb disks gives you 250gb of storage, but one disk can fail without data loss.


Raid 5 - minimum of three disks required, 3 x 250gb would give you 500gb of storage as you lose a third of the space for the redundancy, 4 diks you lose a quarter, 5 disks you lose a fifth and so on

Raid should be controlled at a hardware level which is invisble to the running operating sytem.

S

 

[Will]

there are only three types of raid, microsofts incarnations are utter bollox...


S

Nope (on the only 3 types part anyways)...theres plenty more than 3! Especially when you start to consider nested arrays, RAID 50 anyone?

RAID 0 technically technically shouldn't be called RAID either (where does the 'redundant' bit come into striping, where a single disk failure means you will lose all of the data? ).

Back to my own experiences, I run RAID 1 for my music/documents/videos on a home PC with 2x 200GB hard drives. Generally its been fine, ironically since running RAID I've never had a drive in the array fail but I have tested 'rebuilding' the array from either drive by simulating a failure and its worked fine.

The only problem I've had was when the controller card died (Adaptec 1210SA) which corrupted the data on both drives, so I had to start from scratch. The ideal solution for me would be RAID 0 with a spare 200GB drive, and Norton ghost. As Oedipus says, theres still potential for data loss to occur in ways other than drive failures.

 

[snowflake]

I'm right

honest mister!!

Any other incarnations are variations on the theme

I also forgot to state rule 1............

Data does not exist unless it is in two places

S

 

[greg]

Data does not exist unless it is in two places

S

Wow issues of philosophy and physics raised in one line - nice.

 

[greg]

...I make good tea, can clean windows and if needs be I can be used as a VERY effective draught excluder.

Peter

 

[greg]

Your confusing redundancy with reliability. Putting 6 drives on a raid controller gives you redundancy, but there are a number of other features that are needed to turn that box into a reliable system.

I utterly agree - if we were discussing IT. But I would be happy to take my chances for a domestic music serving solution. The biggest objective/benefit I would be seeking is extensible storage space - I wouldnt even bother configuring a hot spare on a six disk array.

All that said, I would encourage you to build a RAID based system - someone should - so that we can all compare notes on the problems we've had in a couple of years time

I'm hoping you start out with three drives to see how you feel about adding a forth drive to the array without having a backup

I'd take my chances because I have the CDs/DVDs

The #1 reason why I didn't want to go with RAID was because of HEAT and NOISE (fans to cool the heat, and the drives themselves). The more drives the more heat (say 10watts each). Moreover the more drives, the more noise. I know it's possible to run raid5 with less than 5 drives, but as I needed less than 800Gb I figured two 400's better than 5x200 in raid. My mistrust of cheap raid array controllers would have pushed me down the software raid path. I already have 5 drives in another "server", so I know what cooling that sucker takes, and the resultant noise

It all depends on what hardware you choose, I personally would tend to always choose hardware RAID control, though in this case software based is a consideration because the performance hit on the CPU isnt a problem.

I also really thought hard about which kind of box to buy: you mention a dell server, but I'm almost certain that you wouldn't want one of those at home because of the noise. My dual processor 3GHz P4 with nVidia FX2000 sounds like a jet artcraft at times (in the office) and that is merely a workstation.

As a good comparison - on of our hosting servers - a 2U IBM X Series 345 - 6 disks SCSI array - 8 fans (8?!) - sounds like a Boing 747 warming its engines up! Very over engineered.

But our recently bought SATA based Dell PowerEdge 1800 is very quiet - and it contains 6 disks in a RAID array. I'd happily have it at home though obviously not in the listening room - its actually quieter than most desktops and at home we'd only configure it with 1 CPU.

In short - you make some good point regards the importance of the broader picture when considering issues of redundancy but I am happy that for the purpose - a Dell PE 1800 with six disks would form a good home entertainments server and also act as a general home data/storage solution (photos, docs, etc.) - if I did consider a NAS solution then this would also be mindful of the additional scope to support other domestic data storage functions beyond just music serving -but obviously the costs go up. Do you see what I mean?

 

[lAmBoY]

Another thought I had was actually spinning down the drives when they are not in use, or just keeping the single active drive spun up. This would certainly reduce the noise and power etc. However, I'm not entirely sure that that is a good idea as the failure rates for the drives might change with repeated starting and stopping. (Any data lAmBoY?)

ATA drives (sata or pata) typicaly have a CSS spec of 50K (Contact start Stop - or power cycles). So...Lets say you want your home audio server to power down after an hour of no use to save heat, noise, money.

If you do this 5 times a day.....//does maths in head//......you can do this for a considerable number of years before you run into trouble.

BUT!!!! Even though the drives are reliable, I think you would need a very good PSU to match that reliability.

BUT!!!! I personaly would only power down once a day (night time when not in use) as leaving the drives idling can actually help reliability.

Reliability is the key word for RAID systems, and key to reliability is heat. The cooler you keep your drives, the longer they will last - simple as that. Leaving a home server with a conundrum - pitching cooling against unwanted noise. When you can hea your media RAID box situated in a bedroom - from your living room - it simply wont work.

From my perspective you should all build massive RAID boxes with high end fibre channel drives

But when I build mine - it will be a 2 drive system tops. Then a nice 400Gb external SATA drive for weekly backup. Or - hire some server space - say a couple of terrabytes and use you broadband link to backup - let the server provider buy the fibre channel gubbins

 

[oedipus]

ATA drives (sata or pata) typicaly have a CSS spec of 50K (Contact start Stop - or power cycles).

BUT!!!! I personaly would only power down once a day (night time when not in use) as leaving the drives idling can actually help reliability.

Thanks for the heads up on powering starting/stoping the drive. Spinning drives up and down in somwhat far in the future at the moment as I've been busy for the last couple of days getting (what should have been) far simpler stuff to work!

 

[lAmBoY]

Hi Oedipus - whatya working on? PM me if you need more specs, design considerations and stuff.