[mnkynifefite]

I'm currently building a media server and would like to go the RAID 5 route. I'm going to get a 3ware 8-port RAID controller but only plan on using 4 of the ports right now. Here's my question- If I currently want to run 4 Drives @ 160GB ea, and later want to add on drives to the array, is this possible?


As I currently understand it, once you build an array that's it, you would have to wipe everything and rebuild the array if you want to add additional drives. Is this correct? I vaguely remember hearing/reading something about using Linux with LVM, and that this would allow you to do this?? True? Also, is W2K able to do this? I'm not really a linux guy, but willing to learn if this provides me the option.


Thanks!

 

[Brian Puccio]

That's correct, you can no non-destrively add to a 3ware card, I've used them at work a few times, but never had to do that, so I had to verify. I was told by several people at 2cpu forums and as well as a LSI tech that the new LSI card do let you do that.


I'm pretty sure it can be done with software RAID in linux, but I think it's still beta-ish (in development) so I wouldn't go trusting data to it yet. Though you always have a back up still, right?

 

[mnkynifefite]

Are there particular models of the 3ware card that allow you to non-destructively add additional drives to the array or do all of them do that? I have ordered a 3ware Escalade 7810 8-Port IDE-Raid. Is this a function of this card?

 

[bhiga]

AFAIK, neither the 7x10 nor 7x50 cards support expanding the array's size without redefining it.


You could define a new array and use Windows to span the two arrays, but IMHO that's asking for trouble - too complex.

 

[Brian Puccio]

Quote:

Originally posted by mnkynifefite Are there particular models of the 3ware card that allow you to non-destructively add additional drives to the array or do all of them do that? I have ordered a 3ware Escalade 7810 8-Port IDE-Raid. Is this a function of this card?

Sorry, typo in what I wrote:

That's correct, you can not non-destrively add to a 3ware card...


Forgot the "t".


I agree with bhiga, creating two seperate arrays and than spanning them is just a pain. I will be purchasing a LSI card based on my experince with their SCSI non-RAID adapters and the rec's here:

http://forums.2cpu.com/showthread.php?s=&threadid=40665


Hope that helps

 

[xstanbx]

I have an Adaptec SCSI card (2000s zero channel) when used with the adaptec storage manager software allows me to add drives to an array. I have tested it and stressed it while it was preforming the resize by copying GBs of files on to and off of the array and it worked like a charm. Of course loading the array while it was performing the resize significantly slowed down the resize but it didn;t skip a beat. Once it was complete it appeared to windows as a larger drive but with 2 partitions, one being the original array and a new one equal to the new drive added. I then used partition magic to resize the partition.

 

[xstanbx]

Oh by the way, I am using 200GB IDE drives in my SCSI array by using the Acard IDE-to-SCSI converter. Effectively, I am going to be able to build what will appear to the OS as an SCSI U160 1.3TB raid 5 array for about $1,500...... fun fun fun

 

[mnkynifefite]

Quote:

Originally posted by xstanbx Oh by the way, I am using 200GB IDE drives in my SCSI array by using the Acard IDE-to-SCSI converter. Effectively, I am going to be able to build what will appear to the OS as an SCSI U160 1.3TB raid 5 array for about $1,500...... fun fun fun

xstanbx,


Are you running RAID 5 in your set-up? If so, I think I might cancel my order for the 3ware card and head your route!

 

[Esben]

You can resize the array under Linux.

http://www.avsforum.com/avs-vb/showt...hreadid=267133

 

[jcruse]

I just tested this with my LSI Logic MegaRAID i4 card this weekend. It takes forever to rebuild the array after adding a disk (about 48 hours), but it retained all the data. The term for what you are looking to do is "online capacity expansion", and only a few cards support it.


Not sure I'd recommend this card yet, since the documentation is awful, and making it work with XP has been a challenge. But so far it's been ok.

 

[Sokoloff]

Quote:

Originally posted by bhiga AFAIK, neither the 7x10 nor 7x50 cards support expanding the array's size without redefining it. You could define a new array and use Windows to span the two arrays, but IMHO that's asking for trouble - too complex.

Certainly if you are using this under Linux, symbolic links get you out of the problem very easily. Even under windows, you can probably work out a scheme where you introduce an artificial breakup of your data (by first letter of movie, by project name, by media type, whatever) that avoids having to treat the whole ball as a monolithic chunk of storage.


(I agree that you don't want to span, mostly because I don't see a need to span... )


Live re-sizing of a RAID array has two problems:

1. It's slow as hell.

2. On some implementations, the array is "degraded" (meaning not redundant) during the resize.


Between #2 and my own propensity to "fat finger" during upgrades, I'd backup the array first before the upgrade. Where would you be able to backup 750GB of data conveniently?


I'd say build the 4 drive array now and build a second one later as you need it.


---Jim

 

[mnkynifefite]

Quote:

Originally posted by Sokoloff I'd say build the 4 drive array now and build a second one later as you need it.

Please forgive my ignorance but do you mean that I can use my 8-port 3ware card to build a 4 drive array, 160GB ea (160GB * 4 - 160GB = 480GB total) and then at a later date using the same Controller card use the additional 4 ports to build an additional 4 drive array?


If so I guess the biggest disadvantage is that I'd be losing 160GB total:


> 2 4-drive arrays @ 160GB = 960GB

> 1 8-drive array @ 160GB = 1120GB


Is that correct?

 

[Doubly]

Sorry if this is OT, but I was wondering if serving media really needs RAID 5?


I am currently using RAID 1 with two WD 120GB with the 8MB caches on a Promise ATA RAID card and it seems to be more than fast enough, although I have not yet started to serve video. Will this setup be too slow for video?

 

[mnkynifefite]

I'd love to do RAID1 but can't see myself buying and running 16 160GB Harddrives! Plus it seems like "wasted space" to me.


> 8 HD's @ 160GB on RAID 5 = 1120GB

> 16 HD's @ 160GB on RAID 1 = 1280GB

> 16 HD's @ 160GB on RAID 5 = 2400GB

 

[Sokoloff]

Quote:

Originally posted by Doubly Sorry if this is OT, but I was wondering if serving media really needs RAID 5? I am currently using RAID 1 with two WD 120GB with the 8MB caches on a Promise ATA RAID card and it seems to be more than fast enough, although I have not yet started to serve video. Will this setup be too slow for video?

I'm using RAID5 for reliability (survives any single disk failure), not for speed. (Anything is plenty fast for serving [not necessarily editting] video.)


To the previous poster, yes you can use the 8-port controller card for 4 drives now and for a second 4-drive array later. You do lose an additional drive's worth of space, but I'm not convinced that's such a big deal. (If you REALLY cared, you could back up all your data, destroy and re-create the array with 5,6,7 or 8 drives and dump it back on there. Personally, I'll "waste" the extra 250GB drive when I fill up my first 3/4TB...


---Jim

 

[Mr.Poindexter]

Raid 5 is substantially slower than raid 1 or raid 0 in WRITES because it needs to calculate the parity. That is not a problem with READS, so a media server would be best to use RAID 5. While I am not certain how long it would take to rip 400 DVDs onto a server, I know it took several days to rip 400 CDs in APE. I wouldn't want to go through that again if I could avoid it.

 

[Esben]

RAID5 isn't slower writing than a 100 Mbit network is transmitting data. The array will not limit write speed. At least that's the case under Linux with the software RAID5 array. With a Windows 2000 software RAID5 setup, writes will be very CPU intensive, and without a very fast CPU you will likely be lmited by that.

I don't remember the exact transfer rate, but I believe it was around 11-13 MB/sec, with a 1,4 GHz Athlon. Still, around 4 MB/sec wouldn't feel slow or cause slow CD-ripping

 

[Mr.Poindexter]

This is assuming that you are ripping over the network. The most efficient ripping is straight to from the server. I know that when I was ripping and compressing with APE for all my CDs, the server was the fastest ripper. If I was running DVD ripping and not being very CPU intensive, then the gap would have been even greater.

 

[Brian Puccio]

Enter GigE over copper