[Novalug] NAS questions

Peter Larsen plarsen@famlarsen.homelinux.com
Wed Jan 28 16:40:57 EST 2009


On Wed, 2009-01-28 at 15:08 -0500, Jon LaBadie wrote:
> I'm considering adding storage via an NAS box to
> my lan.  It looks like 4 drive boxes can be had
> for under $500 and populated with 4 large drives
> the total cost would be less that $1K.

Sounds like my solution. I wanted initially to go with a freeNAS but I
wasn't interested in a full tower and I wanted hot-plugable. To build
that, the hardware price alone would far pass the little cute box
enclosures with built in LAN that's out there.

So for Christmas I got a FreeStor 4020. At MicroCenter I had picked up 3
680G drives for next to nothing and things plugged in right away.
(http://www.freedom9.com/products/product.php?p=17).

The box is a Linux box (of course). I think it's puppyLinux but it's
heavily modified.

> My home lan has mixed Linux, Win XP, and Solaris.

Pretty much the same here.

> couple of queries:
> 
> What FS do you typically run on these boxes.  

Ahh - this is a misunderstanding of NAS. The FS is internal to the box.
You see a "share", either Windows share or NFS share. Whatever
filesystem the box uses doesn't matter to your OS. As a matter of fact,
it uses a very convoluted "nas" system to manage volumes, iSCSI,
security etc.; other than standard md devices, the rest is very
"special". The good news is that you don't see that as a user on each
host. Only if you, as I do, SSH to the box, do you see how complex the
machinery actually is.

> Do
> you follow the herd and use one of the Windows
> formats accessing it in the unix world with samba?
> Or do you use a more reasonable unix fs and serve
> it to the win boxes with samba on the NAS server?

Neither. You use the Web-control (on mine the SSH isn't enabled unless
in support mode - they were kind enough to tell me the secret way to
enable SSH and I'm a very happy camper now). You first setup the RAID,
and then you create "folders"/"shares". These are logical volume slices
out of your RAID, and because it is NAS you can easily expand volumes
later - so don't make them way big if you don't need the space now. You
cannot SHRINK volumes, but expanding is easy.

Once the shares are defined, you allocate them to users. You create
either windows users or hosts (it uses samba, so one is smbusers and the
other is for /etc/exports). You then assign users/groups/machines to
each folder and you're done. 

A windows user will, once logged in, see the shares he has access to -
just as ordinary windows shares (the fact that the box uses XFS doesn't
impact the user - the whole point of NAS). A linux/solaris user gets a
mount point, and he will see the mount-point as any other NFS share.

My box can become an AD member - in which case you have central security
on the WINDOWS side. And here's the big issue - if you want to share the
same files between windows and linux, you have to do some foot-work. I
haven't completed mine yet - but basically you need to find a central
security scheme with RADIUS or LDAP etc. and coordinate the IDs with the
IDs on the NAS. I've found no way to map user IDs via NFS, so it's
essential that the high-id-values that the box uses internally are the
same IDs that you use when you access through NFS. Otherwise, files
written by your Windows user are not going to be accessible to Linux and
visa versa.  This would be a problem in all NAS solutions.

Alternative, you can use mount.cifs (the new mount.smb) and use windows
shares that does user-mapping for you. 

Bottom line, to make file-sharing work across systems, you must do
something to get a common security scheme running. Of course, if all you
want is a private storage in a shared location, it's simple.

I found out, that the box also runs iSCSI. I haven't enabled that on
Linux yet (it's used for the backup solution) - but it may actually
provide better performance than NFS. That, however, will not allow you
to share files between systems - but it gives you a big storage outside
your box to write/read from - which will perform good (not great - but
good).

> Do you typically use the boxes raid facility to
> protect against hw failure?  Maybe a pair of Raid 1's,
> or a 1+0, or maybe even Raid 5?

In most cases you would use some kind of raid. Raid makes reads/writes
faster since you use multiple disks concurrently. Also, the reason most
people want storage like this is some kind of safety that they don't
loose data. RAID5 would be the most common, or RAID1 if you only have 2
disks.

> Any recommendations on price, performance, features,
> ease of use?  I'll be on a 100Mb lan, so I expect
> performance to be limited by the pipe.

The FreeStor4020 worked right out of the box - easy to setup and use. My
only problem is, that I don't think they've published the source as they
should since it's fully based on open-source; I've put it on my to-do
list to talk to them about it. The box is small, and seems to be put
together well. It would be a shame if they have to recall them all
because they violated a simple license.

As "complaints" would be, that SSH isn't officially supported. RSYNC
isn't included etc. so using it for quick Linux backups is not easy.
Otherwise I'm very happy about it's performance and usage.

-- 
Peter Larsen <plarsen@famlarsen.homelinux.com>
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