NAS devices

[blu-Z8efaSeK1ezqlBn2x/YWAg at public.gmane.org (Edward Ned Harvey)]

> From: discuss-bounces-mNDKBlG2WHs at public.gmane.org [mailto:discuss-bounces-mNDKBlG2WHs at public.gmane.org] On
> Behalf Of Jerry Feldman
> 
> A while back we had a discussion on NAS devices. It appears that my
> office is expanding. Currently we are using a Linux system with non-
> RAID
> drives serving both NFS for our 9 Linux systems and a few directories
> exported via SAMBA. That Linux box is a SCSI box that is pretty well
> maxed out. We currently have over 800GB of data. For backup we are
> using
> a WD Mybook 2TB system which is adequate but very slow. What I am
> looking for is a rack mounted 1U or 2U dedicated system. All but 2 of
> the Linux systems are in the rack. We currently have a 24 port Netgear
> gigabit switch in the rack. For performance I could set up a NAS
> devices
> on a private network with its own switch connected to the second port
> of
> the existing servers.
> What we probably will need is initially 2TB usable storage in the
> RAID1,
> 5 or 6 configuration to replace the current Linux server.
> One system that looks good is the Netgear ReadyNAS series.
> 
> I would prefer that the systems run Linux internally and support both
> NFS as well as Samba. As I mentioned above, performance is important. I
> don't think that I would need the private LAN option initially. I would
> probably use the higher speed SATA drives. At this point a SAN is
> probably too expensive.
> 
> I'm just looking for personal experience with NAS devices so when I
> make
> a recommendation, I will have some experiences.

Phew ... it's really unfortunate that you have a preference for Linux as a
NAS.  Because it's certainly not the best solution, unless you have some
really specific linux-only application, or something like that.

In terms of performance, reliability, speed, backups, and every
characteristic that I can basically think of mattering in a NAS, I would say
solaris/opensolaris/ZFS would be the better solution.

I'll only go into it further upon request (maybe I'm already wasting my
breath) but I'll highlight the reasons I think are the most important here:

* ZFS supports snapshots.  This means, 99% of the time a user needs or wants
to have something restored from backup, they're able to simply copy it from
another directory.  They don't need any assistance.  It's already available.

* Also because of snapshots, incremental backups and "live" backup servers
are infinitely faster and more possible than linux.  I formerly used rsync
on a RHEL box, spending 10 hrs nightly just to walk the tree and scan for
changes to send to the backup server each night.  Now, my nightly
incrementals take an average 7 mins, which varies based on quantity of
changed data that day, because there is no necessity to walk the tree
scanning for changes.  ZFS already knows which blocks changed, and is able
to simply stream one large sequential data stream.

* ZFS is able to do software raid faster than the fastest hardware raid
controller.  This is because hardware raid solutions only know about device
blocks; they don't have knowledge of the filesystem.  In ZFS, the OS has
knowledge of both the block devices and the filesystem, so ZFS is able to
aggregate many unrelated small block writes into a single large sequential
block write.

And that's good enough.  If this hasn't sold you on ZFS, it's a lost cause.
;-)