[NTLUG:Discuss] looking for raid & controller advice

[Scott Hollomon]

3ware 7506-4LP is a great card, its running now in my web/mail server.  Disk 
manager does indeed work under linux and can be configured to do things like 
email you reports about the array on a periodic basis or notify you when/if a 
drive fails.  It also has a Web based gui (think webmin) for checking on and 
tweaking the raid array (I don't run that, I just ssh in and use the console 
utitlity).  You need to configure the array from its BIOS tool before you 
install the OS.  CentOS (really Red Hat Enterprise Linux) has drivers for the 
card and recognizes it immediately without intervention and sees the array as 
one big drive.

I don't know about whether it insists on being hda as the drives in the array 
are the only ones on my machine.  Whether or not this happens may also depend 
on the MoBo bios and how it treats bootable add-in cards.  

The manual says you should only do hot swap if you are using an "approved and 
recognized how swap drive-carrier".  Strangely the manual is silent on the 
amount of cache. Don't know about expandability, haven't tried any of that 
and don't know how the Promise card compares.

If a drive fails (and you don't have a hot spare), you power down the system, 
replace the failed drive, power up and enter the bios confgiuration, add the 
new drive to the array, save the configuration, reboot the system and the 
rebuild will be done automatically.  At least that's what the manual says.



On Saturday 04 December 2004 1:54 am, Kevin Brannen wrote:
> I need to build a file server for my church.  Rudundancy is a must,
> since I've lost several drives in the recent past (I'm not too keen on
> the WD2000 right now--I might even have some used ones to sell soon).
> I'm thinking a cheap way to solve this (as opposed to buying a NAS
> solution) is to get a semi-low cost computer, add 1G of RAM for lots of
> cache, and stick a 3ware 7506-4LP in it with 3 250G EIDE drives in a
> RAID-5 config, running Linux and serving the files out the Gb network
> port with a Samba server.  (Yes, the 2 clients are Win2k, ugh!)  So far
> so good.  I can get all the parts new, including a spare 4th drive for
> $1500, maybe somewhat less.
>
> However, not ever having used any of the 3ware products with Linux, I've
> got a few questions:
>
> * How big is the onboard cache?  Can't find that on the website.
> * It advertises Linux support, and software called Disk Manager.  Does
> DM work under Linux?  Is it useful?  Or do you just tell the card via a
> BIOS like tool to go RAID-5 and the card handles it all automatically
> and Linux sees the card as 1 big drive.
> * Will this card demand to be the "first drive"?  I've got an extra PCI
> EIDE card in my home computer that insists on being hda-hdd.  I could
> live with this but would prefer the MB drive be hda, and these drives be
> hde-hdh.
> * It advertises hot-swap (ain't gonna do it!) and hot-spare.  How does
> it tell you when it has lost a drive?  Something in /var/log/messages or
> at next boot up?  Or something in /proc/whatever that needs to be
> monitored?  An annoying audible alarm would work, the Promise card says
> it has that.
> * If in the future I want to add 1 more disk because I have room on the
> controller, will the card naturally just "expand"?  (if i have to tell
> it in some setup tool, that's OK)  Or will I have to save everything
> off, rebuild the whole array, then restore the data?  If the latter,
> then maybe I need to add the 4th drive in up front. :-)
> * On single drive systems, I like to use a journaling file system (I
> prefer ReiserFS on Suse and ext3 on RH).  For RAID-5, does a journaling
> FS matter?  Or because of the redundancy will the faster but potentially
> less reliable ext2 do just fine?  (Note, the system *will* be on a UPS,
> so any outage < 5min probably won't even be noticed.)
>
> For those that have read this far.  Has anyone used a Promise TX4000?
> It's *half* the price of the 3ware one, advertises a XOR engine and
> resizing capability (for adding that 4th drive to give me a 750G
> device).  Since the 3ware is about $240 and the Promise is about $110,
> the difference is almost the cost of my spare drive.  Is there any
> reason I should not go for the Promise card?  (looking for good & bad
> experiences)
>
> Linux also gives me the option of using Software RAID, but that will
> require a 4-channel EIDE card because of the number of drives I want to
> use.  Does anyone know if the Promise TX4000 will support a non-RAID
> config; i.e. just be an EIDE controller and not impose HW-RAID on me?
> (please don't tell me how bad Software RAID is, I'm not trying to start
> a big discussion about that, but this is an option I must give due
> deligence to)
>
> Thanks!
> Kevin
>
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> https://ntlug.org/mailman/listinfo/discuss

-- 
R. Scott Hollomon
scott at collinstreet.com