Cluster sizes and Raid Setup

[millers_35]

Ok so I have 2 400GB WD HD's setup in a Raid 0 array connected to the IC7-Max 3 mobo. Problem is the cluster size is 4K. Dummy me thought that the stripe size was the same as the cluster but I was wrong. Anyway I am now wanting to get those drives formatted into 64K clusters. Problem is the drives are pretty much full and cant burn that many dvd's.

Here is what I'm thinking about doing. Please tell if this will not work as I am not to awefull familiar with a raid setup.

Buy 2 new 400GB drives along with a 3ware 8-port raid controller. Set that up in my other 800Mhz computer I am thinking about making a fileserver out of. Set it up in Raid 0 formatting those drives with 64K clusters.

Then after the array builds copy all my existing data over to the new array. Bring down my old array format those two drives and then add them to my new fileserver.

Now my big question is this: The new array in my fileserver is Raid 0, if and when I add the 2 old drives to the array will there be anyway possible to transfer that into Raid 5? Or will it only support raid 0 since that is how it was initially setup?

Sorry if it is confusing as it is to me. I have it thought out in my mind how I want to do it but cant put it into words .

Miller

[gplasky]

Originally Posted by millers_35

Ok so I have 2 400GB WD HD's setup in a Raid 0 array connected to the IC7-Max 3 mobo. Problem is the cluster size is 4K. Dummy me thought that the stripe size was the same as the cluster but I was wrong. Anyway I am now wanting to get those drives formatted into 64K clusters. Problem is the drives are pretty much full and cant burn that many dvd's.

Here is what I'm thinking about doing. Please tell if this will not work as I am not to awefull familiar with a raid setup.

Buy 2 new 400GB drives along with a 3ware 8-port raid controller. Set that up in my other 800Mhz computer I am thinking about making a fileserver out of. Set it up in Raid 0 formatting those drives with 64K clusters.

Then after the array builds copy all my existing data over to the new array. Bring down my old array format those two drives and then add them to my new fileserver.

Now my big question is this: The new array in my fileserver is Raid 0, if and when I add the 2 old drives to the array will there be anyway possible to transfer that into Raid 5? Or will it only support raid 0 since that is how it was initially setup?

Sorry if it is confusing as it is to me. I have it thought out in my mind how I want to do it but cant put it into words .

Miller

I'm pretty sure if you're changing from one RAID type to another (RAID 0 to RAID 5)it will need to destroy the container and build and format the drives. Just get yourself a big external drive via USB or firewaire and copy everything off, conifgure your RAID, block size, ad drives, etc. and then copy everything back on.

Gerry

[dblaine2]

Look at your RAID cards docs.... Does it allow for online transformation? My card does - so it will convert from RAID 0 to RAID 5 on the fly.

[millers_35]

Well I don't have the controller card yet as I'm trying to plan it out before I spend all that money. Here is the card I am planning on getting http://www.3ware.com/products/serial_ata9000.asp

I wish I knew someone that had one that I could borrow for a day. As I really dont want to buy a new one. Think I could buy one at a Retail store "test" out? That would b wrong.

Miller

[waltraud]

Originally Posted by millers_35

Well I don't have the controller card yet as I'm trying to plan it out before I spend all that money. Here is the card I am planning on getting http://www.3ware.com/products/serial_ata9000.asp

I wish I knew someone that had one that I could borrow for a day. As I really dont want to buy a new one. Think I could buy one at a Retail store "test" out? That would b wrong.

Miller

Hi,

quote form the Datasheet->

The 3ware 9500S hardware RAID controllers
include advanced RAID features ..[deleted some marketing gibberish]... enhanced firmware platform that allows features such as on-line capacity expansion (OCE), RAID Migration and ....

So you should be able to migrate to a different RAID level.

BTW I wouldn't mess around with the stripe size of the RAID unless you know exactly which blocksize is used to write and read data from the disk and even then the perfomance gain is probably minimal. Worst case it might even get slower.
If SageTV is using blocks of 64K you should not set the stripe size to 64K anyway because you lose the RAID advantage of being able to access multiple disk at the same time. I also saw that this controller has onboard cache. So in a fairly low bandwidth and IO enviroment like a HTPC the cluster size probably won't make any difference at all.

[millers_35]

Ok cool thx for the info. yeah on the existing array I have the stripe size 128 which I believe is what it defaulted to. I didnt mess with it.

Miller

[stevech]

are these 3ware raid 5 cards really $600 ?

[BobPhoenix]

I just got a 9500S 12 port on ebay for just under $400. Get to pick it up at the post office today .

Newegg price for new 12 port is $729.99.

BobP.

[mdmint]

Originally Posted by BobPhoenix

I just got a 9500S 12 port on ebay for just under $400. Get to pick it up at the post office today .

Newegg price for new 12 port is $729.99.

BobP.

Great deal on the 9500S-12. What size drives do you plan hanging off it?

I paid $479 new for my 9500S-8 over two years ago. Been working flawlessly, running RAID5 with online spare. (only itty-bitty 8x250Ger drives, back then not much option SATA) No problem keeping up recording 5 SDTV shows simultaneously while playing back previously recorded on 3 Clients. You must have write back cache enabled however or you'll get some stuttering that heavy a load. But then, why wouldn't you have write back cache enabled for the performance anyway?! I know the normal reason: possible loss of data if Server lost power with data not written to disk from cache, but that's a mute point if recording shows anyway AND my UPS good for ~100min. And 9500 series does have an optional controller battery backup, but don't see the need for Sage server.

[BobPhoenix]

Originally Posted by mdmint

Great deal on the 9500S-12. What size drives do you plan hanging off it?

I paid $479 new for my 9500S-8 over two years ago. Been working flawlessly, running RAID5 with online spare.

I'm replacing a HighPoint 1820A. Right now it is 8 250GB WD drives with one hot spare. Thinking about going Raid50 with two Hot Spares or just Raid5 with two arrays since would have more than 2TB with 250GB drives. Already have a 3Ware 7506 12 port with 200GB drives to make just under 2TB. That one cost me over $600. Still can't trust ebayers though. It was listed as new and even came in a sealed anti-static bag - but it was obviously used. Matter of fact looked extremely used based on the PCI card edge. Even cards that I've inserted and removed dozens of times don't look this bad. The card works well so far and was over $100 cheaper than the 9500S 8 port at Newegg so guess I don't really care.

BobP.

[stevech]

earlier in this thread, it was said that the person was using RAID 0.
Isn't true that RAID 0 has no redundancy to protect from drive failure?
If so, what is the method to preclude data loss with RAID 0?

I'm debating RAID 1 mirroring vs. spending more than I want to for RAID 5.

[BobPhoenix]

Originally Posted by stevech

earlier in this thread, it was said that the person was using RAID 0.
Isn't true that RAID 0 has no redundancy to protect from drive failure?

Correct Raid 0 has no redundancy so if one drive fails all data is lost.

If so, what is the method to preclude data loss with RAID 0?

Best way is to do daily backups that way you only loose data since last backup.

I'm debating RAID 1 mirroring vs. spending more than I want to for RAID 5.

Actually Raid 1 costs more once you get to larger numbers of drives at least. With Raid 5 you only loose the space equivalent to one drive but with Raid 1 you have to double your drive count.

BobP.

[stevech]

Is Windoze smart enough (or is it in the controller) to send RAID 1 read requests to the drive that's not busy reading for some other process?

Maybe I can find a RAID5 IDE controller that doesn't break the budget.

[BobPhoenix]

Originally Posted by stevech

Is Windoze smart enough (or is it in the controller) to send RAID 1 read requests to the drive that's not busy reading for some other process?

Someone else had better answer this one because I always thought with Raid1 reads were from the same drive in the pair for every read.

Maybe I can find a RAID5 IDE controller that doesn't break the budget.

Ebay is a good choice just don't expect new to actually be NEW.

BobP.

[mdmint]

Originally Posted by BobPhoenix

Someone else had better answer this one because I always thought with Raid1 reads were from the same drive in the pair for every read.

With a good Raid1 controller (or software control as is often the case with cheaper Raid1 or 0 implementations) can read from either drive as needed. Writes however are concurrent. So in theory Raid1 (mirroring) read requests may be faster but writes may actually be slower than stand alone drive because of control overhead. How well Raid1 actually performs versus stand alone (or Raid5) used with a Sage Server I can't say, set mine up Raid5 from the git go. Regardless a better controller with hardware cache will give better performance than any software Raid implementation or cheap controller.

[Osoksniper]

Promise technology started the whole raid thing back many years ago and, they still make raid controllers that are both very fast and very flexible, hardware(preffered) and software driven. The new system boards, the p45 and xfx format 775 boards all come with raid 0 to raid 10 so, if you use raid are you only using the raid 5 for the data or are you using it for the whole pc, system and all? I usually mirror the system drive and raid 5 the rest, just wondering...sounds like raid 5 is good all the way around...have done that before too and never lost a machine yet that way. Also, I have now the adaptec however, it is not as fast, even with the clusters and sector sizes set as large as possible. This is the most wasteful way to format one however, the right way to go with video where you're moving such large files so quickly. I have a server with 4 tuners and can record 3 currently, play back one on the big screen in the living room and using place shifter, play back two others through the wireless N without killing it...it is pretty maxed out though...so am moving to a new server and looking to upgrade pretty much everything.

[stevech]

I use RAID1, hardware on the mobo.
It's not "if", it's "When" a drive will fail.

It used to be "when" Microsoft's file system would self destruct. Not so now with NTFS.