Looking For RAID Hardware/Software Advice

[Mark Phillips]

On Fri, Jan 16, 2009 at 9:58 AM, Craig White <craigwhite at azapple.com> wrote:

> On Fri, 2009-01-16 at 09:36 -0700, Mark Phillips wrote:
> > I am running out of room for my backups. I use backuppc and I have
> > almost filled a 150GB drive with backups from 7 computers, and I need
> > to add another 2 computers to the set. I have an old Dell Poweredge
> > 1300 server (Pentium III 550 Mhz, 500 MB RAM, PCI 33.3Mhz) that I
> > could turn into a backup server. I am looking for suggestions/thoughts
> > on how to set this up. I need to keep the cost down as much as
> > possible; under $150.
> >
> > My initial thoughts:
> >
> > * Keep current 72 GB drive for OS (debian testing, about 68% full)
> > * Add two 500 GB SATA drives and a PCI SATA controller ~$130
> > * Software RAID and LVM for the two drives
> > * Move current 150 GB of backups to the RAID
> > * Backuppc now runs on this machine and slowly fills up the RAID
> >
> >
> > My questions:
> >
> > 1. Should I keep the 72 GB drive for OS, or put it on the RAID?
> >
> > 2. I can add another CPU (P III 550 MHz) processor to the box - is it
> > worth the effort to find one? I found one source for $5/CPU, I just
> > need to find the heat sink and mounting hardware. Will this improve
> > performance?
> >
> > 3. The box has a built-in SCSI 68-pin Ultra2/wide bus/controller, but
> > SCSI drives are more expensive, at least from a cursory google search.
> > Is this correct? I don't think I can use SCSI drives within my budget
> > constraint.
> >
> >
> > 4. Would upgrading the memory to 1GB improve performance - top shows:
> > Mem: 646676k total,      639300k used     7376k free,      64548k
> > buffers
> > This would add another ~$60 to my cost.
> >
> >
> > 5. Should I look at hardware RAID cards - they seem very cheap, so
> > perhaps software is better?
> >
> > 4. Does this plan make sense, or is there a better way to proceed for
> > about the same cost?
> ----
> 1. One of the tricky things about backuppc (and I don't use it so I am
> working from just a general understanding of things) is that it
> creates/utilizes lots of hard linked files so if the boot os dies, your
> backup may die along with it. The point of RAID is the redundancy part
> which means things just keep working even if there's a complete failure
> of a single hard drive (assuming everything but RAID 0). Having a RAID
> array for your OS would ensure that.

OK, then I can dump the old OS and do a fresh install. Appears to be a
little easier with Debian these days for RAID and LVM.

>
>
> 2. Real hard to match processors at this point and unlikely you would
> find one that exactly matched. Might be easier to find 2 that match each
> other and install them both but for a backup box, that seems
> unnecessary.

I was trying to find another use for this monster (ie big imposing black
Dell case....), so I thought I would have some fun with a dual processor.

>
>
> 3. Yes, SCSI drives are more expensive - but performance should be much
> better.
>
> 4. RAM may help a little. Free shows output of virtual memory but
> doesn't suggest how much real RAM you have there. Assuming a text based
> interface (not GUI), 256 MB RAM for what you're doing should be enough.

There is currently 512 MB installed.

>
>
> 5. Cheap RAID hardware cards are cheap because they suck. Most of the
> SATA 'RAID' cards are either 'fake' RAID (they aren't really hardware
> RAID) and perform especially poorly on commonly used RAID 5 (3 drives
> minimum but maximum drive space).

So, I need three 500GB drives, not 2? And 3 PCI SATA controllers (based on
your comments below)? Any recommendations on manufacturerers? Do all three
drives have to be the same?

>
>
> 6. Makes sense.

Especially since you are better at creating a list of 6 consecutive numbers
than I am. ;-)

>
>
> Software RAID works well. You can create a RAID volume for your OS is
> you wish - i.e. one drive on SCSI and one on SATA but the suck thing is
> that...
> - You can't just convert from an existing filesystem to a RAID array.
> You'd have to copy it all off, create your RAID array, copy the files
> back and then fix the boot issues
> - RAID works much better if the drives are on different controllers - a
> controller can only write one drive at a time.

Thanks!

>
>
> Craig
>
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