# Software or hardware RAID-5?

## GrimReaper

Hi people,

I'm currently in the planning stages of building a RAID-5 system for work.

This will be used by the mac people at the company I work at for storage of art etc (I work for a printing company that has an art department.. for example a single leaflet will take between one and two cd's worth of storage, the current method of storage backup being lots and lots of cd's/dvd's)

What i'm planning is creating a RAID-5 system that has between 1TB and 2TB of storage (currently looking at 6x 250GB HDD's for 1.2TB).

My question is what do people recommend hardware wise? (this is on a 100mbit network btw)

Since the mac people are limited to transferring, retrieving and searching at 10MB/sec it seems to me that a software RAID is the better option since hardware RAID will deliver little in performance difference across the network. (the Mac people wouldn't notice any performance differences)

So, i'm probably more asking for what IDE controller cards are well supported or that people have good experience with under Linux?

Netatalk or Samba-3 (with utf-8 for funky mac filenames, might use both) will be used for accessing across the network.

A monthly backup regimen will probably be created, whereby we backup the entire contents of the RAID ssytem to either a bunch of tapes or a bunch of DVD's (dual layer) and kept offsite incase of fire or somesuch.

----------

## chammer

i recently built a server like this for the company my mother works for. they did not have a big budget so i basically laid out 3 systems, and they went with the middle of the road system. this middle of the road system i laid out went with 4 80gb western digital se drives (8mb cache 7200rpm), and a promise ultra 133 tx2 controller card. put the first pair on the motherboard's primary, put a cdrw on the secondary, and the other two drives on the promise card. you can probably guess right now what im getting at...software raid.

the system is doing software raid5 across the 4 drives, and the performance is quite excellent. since i built it in my house beforehand, i had the chance to pound it from my two gigabit machines as fast as it could go. the cpu activity from the raid5 daemons never got above 3% usage. it handled the load very very easily. i would love to have done *true* raid, using a lsi or 3ware card, but alas, no budget for them.

anyways, the results are excellent, and surprised me how good the system is, and the controller card i used to hook up the other two drives can be had for $35 from newegg. the link is below:

http://www.newegg.com/app/ViewProductDesc.asp?description=16-102-007&depa=0

at any rate, the best thing you can do, since the drives will more than keep up, is to make sure the file server itself has as fast as possible lan connection. i did 10/100 for them and using 100mbit cards in each of the client machines since there are only 3 of them. of course, using samba to share out. but, if you have any more than a few machines that want to transfer large files  at the same time, i'd say since its cheap...go with a gigabit switch and a gigabit nic for the fileserver. at home i personally use the netgear 8 port gb switch, and a couple intel desktop mt gigabit nics ($140 for switch, $45 for nics at the time). even with the clients running 100mbit, if you can get gigabit to the fileserver it'll help a great deal.

hope this bit of information helps in some small way.

----------

## GrimReaper

We currently have the problem of the macs using appletalk and tcp/ip (generates lots of traffic, it's a lot like ipx/spx) so at the moment the macs are on a hub whilst the rest of the network are on two 100mbit 24 port switches.

The macs currently have speed problems because the mac portion is not seperate from the rest of the network via a router to filter out the crap that is appletalk.

I currently have a 16 port gigabit switch sitting on my desk doing nothing because at the moment i'm also figuring out a way to phase out the Macs dependances on Appletalk. (OS 9.x and 10.x machines)

They can access MS samba shares so i'm currently planning to get them to use that for any file sharing between machines.

Appletalk will kill network speed if you put the macs that use it on switches.

----------

## GrimReaper

 *chammer wrote:*   

> i recently built a server like this for the company my mother works for. they did not have a big budget so i basically laid out 3 systems, and they went with the middle of the road system. this middle of the road system i laid out went with 4 80gb western digital se drives (8mb cache 7200rpm), and a promise ultra 133 tx2 controller card. put the first pair on the motherboard's primary, put a cdrw on the secondary, and the other two drives on the promise card. you can probably guess right now what im getting at...software raid.
> 
> the system is doing software raid5 across the 4 drives, and the performance is quite excellent. since i built it in my house beforehand, i had the chance to pound it from my two gigabit machines as fast as it could go. the cpu activity from the raid5 daemons never got above 3% usage. it handled the load very very easily. i would love to have done *true* raid, using a lsi or 3ware card, but alas, no budget for them.
> 
> anyways, the results are excellent, and surprised me how good the system is, and the controller card i used to hook up the other two drives can be had for $35 from newegg. the link is below:
> ...

 

Is the card supported in the vanilla kernel? (i'm currently building a test system under vmware to see how well samba-3 with utf-8 handles mac filenames, for example stuff with backslashes and forward slashes in etc.)

BTW, I'm in the UK so newegg not much use to me.   :Smile: 

EDIT: Also, what processor are you using in the RAID-5 system?

I'm planning going to build the machine from scratch and i'm currently split on either some decent (normal) motherboard and processor like a sempron or celeron. Or going out full hog and getting a server class motherboard and Pentium 4 (or Xeon) processor.

The budget i've allocated myself for this is £1000-2000.   :Smile:  (£1000 = $1,793.74)

----------

## GrimReaper

Did you use the following under the kernel for the ide controller?

"ATA/IDE/MFM/RLL support" > "IDE, ATA and ATAPI Block devices" > "Promise PDC202{68|69|70|71|75|76|77} support"

----------

## chammer

yep, that kernel option is correct.

then under multi-device support i have:

yes to the multiple devices support, raid support, raid0, raid1, and raid4/raid5 options (even though i use just raid5).

the specs on the machine are pretty modest. its as follows:

amd 2000+

512mb pc3200

abit nf7-m nforce2

4x80gb wd se

smc 10/100 nic (1244tx)

plextor 52x cd-rw

promise ata133 controller

price came in at just under $1000. not sure what that is in pounds. most expensive bit was the drives, taking up about 1/3 the cost. i also put it in a full tower of course, an aopen h700b.

since this is 100% fileserver, the cpu/ram did not have to be all that great. i had thought about skimping even more on them, but figured it'd be room for growth should they need to start pounding it. as it is, it sees very minimal use, so both the machine and storage amount is way overkill for this application.

 the global samba directory being 187gb and 300mb in use.  :Very Happy: 

edit

forgot to answer the other question about was the card compatible with the vanilla kernel. afaik it should be, but i dont know as i never used it, i use the gentoo-dev sources. however, from the second i turned the machine on for the first time, the bios saw the controller card and once i got to the gentoo cd i installed from, the kernel output on bootup showed the controller card and assigned proper /dev/hdX entries for the other two drives. so i had no issues setting up the software raid. so...im not certain whether or not a kernel driver even needs to be set, but i set that one anyway just in case.

----------

## GrimReaper

The hardware has now been decided upon.

Asus A7V8X-X motherboard

Sempron 2200+

2x 256MB PC2100 Crucial DDR

Lian Li PC-V2000 Silver Full Tower Case (yummy)

6x Maxtor Maxline II 300GB IDE Ultra ATA133 5400rpm (I would go for 7200rpm but they're out of stock)

3x PROMISE ULTRA 133 TX2 2CHNL IDE CONTROLLER

Plus all the usual stuff, cheapo graphics card, cheapo cd drive etc.

I'm also buying one extra motherboard, hard drive and Promise card incase of hardware failure. (that way any hardware can be quickly replaced)

In total it comes to a lovely £1413.02 or $2535.14 USD.

Oh, for storage it should give me (roughly) a lovely 1.5TB.    :Twisted Evil: 

----------

## TimG

 *GrimReaper wrote:*   

> The hardware has now been decided upon.
> 
> I'm also buying one extra motherboard, hard drive and Promise card incase of hardware failure. (that way any hardware can be quickly replaced)
> 
> 

 

Before you put this into production, you should go ahead and go through the scenario where one of the Promise cards dies on you.  When this happens, the two drives on that card are going to be out of sync and you'll be better off if you've dealt with the problem with non-production data.

Also, a couple of other gotcha's that I ran into.  Heat was a problem.  All those drives build up a lot of heat.  Make sure you have good case fans.  It might not be an issue for you, I'm running 9 7200 rpm drives in the raid (1 is a hot spare) and one system drive and heat was a problem for me.

Also, make sure you have a GOOD power supply.  I killed the 430 watt that came with the case and one supposed 550 watt power supply before I went ahead and shelled out the money for a good 550 watt power supply.  Again, this might not be a problem if you are only running 6 drives.

----------

## GrimReaper

The case i'm buying is a 'Lian Li PC-V2000 Silver Full Tower Case' and the PSU is a 'Antec TrueControl 550'.

They're being bought from www.kustompcs.co.uk.

I'm buying a spare controller card, what happened when a controller card failed on you?

The maximum number of users who will use the fileserver are 3. (two mac users and me)

----------

## TimG

 *GrimReaper wrote:*   

> The case i'm buying is a 'Lian Li PC-V2000 Silver Full Tower Case' and the PSU is a 'Antec TrueControl 550'.
> 
> 

 

LOL, that's the exact same power supply that I ended up using.  It's working wonderfully.  I think you made a good choice.

 *Quote:*   

> 
> 
> I'm buying a spare controller card, what happened when a controller card failed on you?
> 
> 

 

The two drives attached to it were out of sync and the raid would not work.

I used the instructions here to fix it, but for some reason mdadm would seg fault on me when I tried to use it so I ended up using raidtools' mkraid.   It was a little scary because if your raidtab isn't correct, you will nuke your data.

----------

## Crispy Beef

Hi Guys,

Just to jump in with a slightly different question.  Am looking to build a RAID-5 array on a box for a client, they have requested around 4.5Tb of storage.  Have located a rackmount case that can cope with the 16 drives needed (300Gb SATA 4.8Tb so 4.5Tb with the parity stuff).  I'm a little stuck with the controller card to use though, 3Ware has a card that can handle 12 drives which isn't enough, but they have ones that do 8 too, so my questions is can I build the array over two 8 channel cards into one RAID-5 monster.  And will that work under Linux/Gentoo on a Opteron or Athlon64 system?

The cards I'm looking at are the 9000 series from 3Ware.

Cheers for any info.   :Smile: 

----------

## TimG

 *Crispy Beef wrote:*   

> Hi Guys,
> 
> Just to jump in with a slightly different question.  Am looking to build a RAID-5 array on a box for a client, they have requested around 4.5Tb of storage.  Have located a rackmount case that can cope with the 16 drives needed (300Gb SATA 4.8Tb so 4.5Tb with the parity stuff).  I'm a little stuck with the controller card to use though, 3Ware has a card that can handle 12 drives which isn't enough, but they have ones that do 8 too, so my questions is can I build the array over two 8 channel cards into one RAID-5 monster.  And will that work under Linux/Gentoo on a Opteron or Athlon64 system?
> 
> The cards I'm looking at are the 9000 series from 3Ware.
> ...

 

The 3ware cards will work talk to each other allowing you to do a hardware raid over two 8 way cards.  I think they support up to 4 cards, but you should check their website.  I have a 9500S-12 and it supports it.

Make sure your motherboard has 64 bit PCI slots on it.

----------

## Crispy Beef

 *Quote:*   

> The 3ware cards will work talk to each other allowing you to do a hardware raid over two 8 way cards. I think they support up to 4 cards, but you should check their website. I have a 9500S-12 and it supports it.
> 
> Make sure your motherboard has 64 bit PCI slots on it.

 

The mobo I was going to use has Six 32-bit 33MHz (5-volt) PCI slots (Tyan Tomcat K8S) so I guess I'll have to have a look at something else.  Is it that the 3Ware cards need the 64-bit slots or is it more due to the size of the RAID-5 array?

Cheers for the help.

----------

## drescherjm

I would get one of the Thunder K8 boards instead and you will have PCI-X.

----------

## drescherjm

 *Quote:*   

> Is it that the 3Ware cards need the 64-bit slots or is it more due to the size of the RAID-5 array? 

 

You will take a performance hit by limiting the whole array to less than 120 MB /s data rate by using a shared 133 MB /s bus (normal 33 Mhz 32 bit PCI). With a multiple PCI-X busses (64 bits and 66Mhz+) on a Thunder K8 you will have many times that bandwith.

----------

## Crispy Beef

Ok, thanks for the info guys, I had the Thunder down as a potential option, but went for the Tomcat as it seemed to offer similar stuff for a lot less.  With the RAID array being 4.5Tb I'll definitely go for the Thunder now.   :Smile: 

----------

## Crispy Beef

The Tyan Thunder boards do seem good and have all I need, Gigabit Ethernet, Socket 940 etc.  But have read a few comparisons with the MSI K8D Master-F Dual and while they both seem to come out very similar, the MSI has what I need at a cheaper price, so I think I'm gonna end up going for that one.  :Smile: 

----------

