[OpenAFS] vos shadow to backup user homes

stephen@physics.unc.edu stephen@physics.unc.edu
Mon, 26 Aug 2013 09:46:45 -0400 (EDT)

Hi Shouri,

I've used shadow volumes in the past. Thankfully I never had to test 
bringing an entire shadow server into production. I also plan to use it in 
the near future (barring contrary advice from the list) for a server which 
houses dozens of TBs of research data for a project which can suffer some 
downtime (as long as it's unavoidable) but not as much downtime as would be 
needed to restore dozens of ~1TB volumes.

I'll leave the topic open though, and would welcome comments on shadow 
volumes from any of the devs.

Regarding rsync, depending on the size of your partitions, its performance 
may make you cry. I use an rsync-based backup application for my non-AFS 
data and am starting to surpass the limits of what rsync can do in a 
reasonable amount of time and RAM on current hardware.

However the main reason I'm replying is your comment about RAID. IMO, 
anytime you're configuring a mission-critical system without RAID you're 
probably asking for future headaches. I think the only time I'd consider it 
is if the system had no unique data on it and could be made part of a HA 
cluster using [heartbeat, etc]. But at that point you're just abstracting 
your redundancy at a different level.

All of my database and fileservers currently use hardware raid (3ware or 
LSI/PERC). But one of my "idle time" projects -- a bit of an inside joke 
since I have no idle time -- is to play around with ZFS on linux to see if 
I feel it's ready for prime time yet or not.

PS. I noticed "Associate Professor" in your signature. Have you consulted 
with your local IT support? If they're not overworked, they may have 
additional advice specific to your site, discipline, etc.


On Sun, 25 Aug 2013, Shouri Chatterjee wrote:

> Dear All,
> I wanted to ask about "vos shadow" and whether it is being used as a solution 
> on production systems to back-up user home directories.
> The most significant information I can find is a thread from this email 
> archive last year. 
> http://lists.openafs.org/pipermail/openafs-info/2012-December/039077.html
> I can dedicate a server to host only shadow volumes. If an active server 
> fails and dies, the shadow copy can be brought online. Is this a better 
> solution than, say:
> (1) keeping a periodically rsync'd copy of the /vicepx partitions on a shadow 
> server
> (2) afs over drbd
> I am trying to use commodity hardware (no RAID, no scope for software RAID 
> either) to build cheap AFS storage.
> Shouri
> ____________
> Shouri Chatterjee
> Associate Professor
> Department of Electrical Engineering
> IIT Delhi, Hauz Khas
> New Delhi 110016
> India
> Phone:	+91 11 2659 1099 (O)
> 	+91 11 2659 1619 (R)
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