Hard Disk IDs in Linux

Michael Torrie torriem at gmail.com
Thu Mar 14 09:21:06 MDT 2013


On 03/14/2013 01:24 AM, Dan Egli wrote:
> I personally DON'T need 120 TB in my home. A simple home server with a 4
> Drive RAID6 is exactly what I had planned on for MY server.

For a home server I recommend RAID1 or RAID10 over RAID6.

> As to file system, that was planned on ZFS unless you guys has a better
> idea. As to the connection, it's probably going to be iSCSI. I have not
> nailed that one down because I'm still hoping to get a smaller machine out
> of my boss, and if I do I'm going to look into what's available at that
> size. 

What kind of chassis?  Most good chassis will do hardware RAID and
export the volumes.  Though there are some bare disk arrays that simply
export devices as SCSI LUNs.  Either way you need a chassis with a power
supply.

Despite people claiming that iSCSI is going to replace fiber channel, I
still find Fiber Channel to be a compelling choice for SAN.  In fact
iSCSI HBAs are still just as expensive as Fiber Chanel HBAs, or more so.
 We're talking between $250 and $600, depending on if you want dual or
single port.  I saw a single-port fiber channel card online the other
day for $50. Prices have sure fallen.  Of course with iSCSI you can do
it in software with nothing but an ethernet port, but you will pay a
performance penalty.  And you max out at just under 1 Gb/s.  FC is
around 4 Gb/s.

I'm not sure how I feel about ZFS... ZFS is not a supported Linux file
system.  It's third-party and licensing conflicts means you have to
compile the modules yourself every time a kernel is updated.  Though
this is largely automated these days with the dkms system that many
distros use.  And maybe there are binary repositories.

I feel that ZFS in and of itself is stable and production-ready (I used
it for years on Solaris without issue).  But I'm not sure of the status
of the zfs-on-linux project.

> I'd really like to convince him to just go for a full tower PC with
> like eight to twelve disks, but I don't know if I can convince him that
> it's a more efficient way to go. He's really stubborn.

Yes, that's likely the cheaper and easier option.  Setting up a large
SAN is quite an endeavor.  I've done it before (though in those days
large meant 20 TB!), and learned a lot about fiber channel fabric, disk
array chassis, fiber channel switches, multi-path LUNs, etc.  I get the
impression your boss thinks the large disk array idea is on the same
order of complexity as throwing disks in a box and setting up a software
RAID.


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