Vex Star

Ok, itunes fucked up my music again. I have backed up all my music but all my ratings and etc are gone. So I am done with the nvidia raid that I have previously used. So I have two options. I’ll be reusing my 2 320gb hd

Build a seperate system, run windows server or linux and run RAID1

found someone selling
P4 630 Prescott 3.0GHz 2MB L2 Cache with Asus P5LD2 motherboard
for $80bucks
Add some ram and i’ll be set.

or

Adaptec SATA RAID controller, model AAR-2410SA for $100

add it to my existing system

I have no clue how controllers work, but everyone raves about hardware raid.

So OT, whats my best choice?
Wait, why are you blaming the RAID? You said iTunes fried your music collection.

on a separate computer, why the hell not?

Hardware RAID for RAID1 isn’t going to be a huge difference. A little bit of performance, but not a great deal. Hardware RAID controllers help substantially when there is parity involved.

why?

RAID1 does not have parity So I’m not sure why you’re talking about the benefits of discrete raid controllers when parity is involved — because that isn’t remotely relevant to raid level 1.

Personally, if you KNOW you’ll never want more than 320gb, then just build a file server, and use a discrete card and a level 1 raid. BUT make SURE you use a decent DISCRETE controller. onboard == fail and aids, unless you’re talking higher-end server mobos.

However, if it were *ME*, I would get some extra drives, and run RAID5.
on a separate computer raid 1 is fine. on the primary computer with a raid card, you should always have a separate backup

I never said RAID1 had parity, I said hardware controllers help substantially when parity is involved, not that RAID1 had anything to do with it. He asked if a hardware raid controller would be beneficial to him, I have him an answer
okay well i think it would have been prudent to specify that you felt that raid5 and an extra hard drive would be benefitital to take advantage of that parity.
I don’t get your hate for onboard RAID 1 solutions – I’m not sure how it can fail so badly that you would have one working drive wors case scenario.

the drive failing isn’t the big downfall of onboard raid solutions — it’s the controller failing.

vhat?
parity = protection against one disk failing or am i wrong?
in raid 1 one data is mirrored against all the drives .. therefore any amount of drives can fail except 1, and you still have all your shit?

im wrong?

yes you’re wrong. what you describe is redundancy. parity is one method for acheiving that redundancy.

so parity implies redundance, but redundance does not imply parity.

ok, what is parity?

ensuring all the data is on at least 1 drive?

no

also, for a raid 1 (for my OSes) what’s wrong with software raid? is it fail and aids? or is it simply slower? by a lot?
how much would a cheap and reliable controller cost?
even if im already doing a raid 5 – I should have 2 raid cards?

i dont think i will setup a raid 1 because i will prob have 3×500gb drives in a raid 5 that ill fit my oses on, but in the future if i begin to find it tight for space, i might buy 2×100gb SSDs (this could be 5 years down the road) to relieve some space in my raid 5 and also do a lot to improve performace.
dont worry today about something you MIGHT do with your computer in 5 years. that’s just stupid.

im trying to understand raid, i asked a question about software raid

edit: still dont get how raid 5 does parity and raid 1 doesn’t. it seems pretty important so i dont think ill do a raid 1, but how does raid 5 have it and 1 doesnt?
edit: im slightly getting it
edit: yes.

raid 1:

A RAID 1 creates an exact copy (or mirror) of a set of data on two or more disks. This is useful when read performance or reliability are more important than data storage capacity. Such an array can only be as big as the smallest member disk. A classic RAID 1 mirrored pair contains two disks (see diagram), which increases reliability geometrically over a single disk. Since each member contains a complete copy of the data, and can be addressed independently, ordinary wear-and-tear reliability is raised by the power of the number of self-contained copies.

raid 5:

A RAID 5 uses block-level striping with parity data distributed across all member disks. RAID 5 has achieved popularity due to its low cost of redundancy. This can be seen by comparing the number of drives needed to achieve a given capacity. RAID 1 or RAID 0+1, which yield redundancy, give only s/2 storage capacity, where s is the sum of the capacities of n drives used. In RAID 5, the yield is s * (n – 1)/n. Using 1 TB drives as an example, four of them can build a 2 TB redundant array under RAID 1 or RAID 1+0, but they can be used to build a 3 TB array under RAID 5. Although RAID 5 is commonly implemented in a disk controller, some with hardware support for parity calculations (Hardware raid cards) and some using the main system processor (Motherboard based raid controllers), it can also be done at the operating system level using Windows "Dynamic Disks" or with mdadm in Linux. A minimum of 3 disks is required for a complete RAID 5 configuration. In some implementations a degraded RAID 5 disk set can be made (3 disk set of which only 2 are online).

In the example on the right, a read request for block "A1" would be serviced by disk 0. A simultaneous read request for block B1 would have to wait, but a read request for B2 could be serviced concurrently by disk 1.
so if there are parity errors reading, then, i guess the data can be retrieved off another disk and hopefully the parity matches, yes?. are errors reported and how?

it’s good for backup in terms of hard disk redundancy. if itunes fubared his music collection, it would do so on both raid disks. it doesn’t make historical backups.

if you’re making yourself a raid for home and you have 2 extra disks, raid-1 is fine. raid-5 requires a 3 hard disk minimum.

depends on the controller. one of the reasons a good controller > onboard.

parity is used for error checking, as well as to rebuild a data set if a drive fails. errors are generally reported, yes. most controllers have some way of accessing the data. often snmp can help collect data and it can be analyzed with cricket/mrtg or other statistics packages.

Yeah, but what’s the big deal if it does? You buy yourself a separate card and rebuild the mirror?
Okay people, get off the RAID thing. He could be running a server cluster connected to a RAID60 SAN and it wouldn’t matter, because what iTunes does to his music collection is its business; the disk, whatever kind it may be, is just going to do what it’s told to do.

But since it’s a going concern, I might as well throw in my two cents: RAID1 is fine for backups even if it doesn’t have parity, because instead it has a complete second copy of the data. You don’t need parity to reconstruct the data in case of disk failure, not when the entire data is redundant.

The problem is that if the onboard controller fails, what are the chances you’re going to find another controller that can detect the existing array and bring it online again without having to wipe the disks?

I, for one, use a RAID so I don’t have to make backups of non-important files, but if the controller fails and I can’t just swap in another identical controller and I end up having to wipe the disks and make a totally new array, then there goes my evil plan.

(I also use it for speed, but that’s not the issue here.)

But iTunes can still kill his music in the same way? = not a good backup plan.

Plan I’m liking is to get 3×500Gb drives in a RAID5. 1Tb storage = loads, to store my OSes, backups of my OSes (including laptop) updated weekly (+1 old to keep incase), my downloaded shit that I will probably find somebodies external harddrive to backup to, but backing that up isn’t worth worrying about, and my important stuff with 4 or 5 spares locally (will be just a few dozen MBs max), and as many as fills my quota at off-site storage (it isn’t my hard disk and I don’t need to listen. I might shop around and pay, or get off a friend, maybe do a deal) – this done nightly or on shutdown.

So I don’t have to fuck around too soon I might fit one hot spare. It doesn’t draw power and can’t piss me off, right?

Anyhow, OP do RAID 1 but if you wanna come back from another iTunes fuck up with your ratings etc (your iTunesDB I would think), you need to back it up. That doesn’t mean mirroring it, when stuff is deleted on a mirror it is deleted on all mirrors I would think (is this right dues?). I suggest you automate copying it to a seperate location on ur RAID 1 with your music, I’m sure there’s programs to do that.

Don’t see the need for a new system.
I agree that any kind of RAID is inappropriate for backing up important files; it’s just a good way to prevent data loss due to disk failure. Nothing can keep you from deleting something by accident, after all. That’s why I said he shouldn’t blame the RAID controller for losing his music in the first place.

Regarding the hot spare — it’s called a "hot spare" for a reason. Yes, the hot spare is on and spinning whenever the computer is on, unless you have some fancy RAID controller that’s smart enough to spin down the disks when it’s not using them.
all this confusing shit wont matter when we’ll switch to solid state drives in the next 2 years.

bullshit. RAID will be as important as ever.

That’s a bit shit. How fancy does it need to be to know that a configured hot spare isn’t needed until there’s a fail?

Even I know that!

lmao

you’re an idiot. it’s a hot spare because it can be kicked into service on-the-fly, and without user intervention.

hard drives CAN spindown when not used.

True enough, but a broken mirror can still be read by another controller – hell even a non-raid controller. You’d have to rebuild the mirror, but that’s a pretty moot point.

Not by themselves. They only respond to commands from the controller.

I’ve got a hotspare in my file server, and I just went into the server room and yanked it. When I tilted it side to side, I could clearly feel gyroscopic action from the spinning platters.

The RAID controller in my file server is a PERC6/i, so that should give you a benchmark. Those cards cost $1000 apiece.
Wow I thought my thread died, so never checked back.

I ended up getting the raid card. I know itunes can still fuck it up, I will keep another copy on an external periodically.

One question about raid 5, I have two matching 320gb right now. Can I add another 320gb from another brand? Cause I can’t find another of the same model that I have.
You can’t do RAID 5 with only two drives, so it’s a moot point.

Edit: Whoops, thought you were adding it later. Yes, you can add a diffferent model. In fact, it’s probably better that the drives are not from the same batch anyway.
It’s better to use the same model of hard drive, because they will respond similarly. 5Gen’s right about avoiding the same batch, though, because that will keep them from failing similarly as well, at least in theory.

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March 19th, 2009 | Tags: cent, Controller, decent DISCRETE controller, disk controller, file server, good controller, identical controller, Linux, main system processor, Microsoft Windows, model, onboard raid solutions, operating system, RAID, SAN, SATA RAID, SNMP, software raid, USD | Category: general | Subscribe to comments | Leave a comment | Trackback URL