Re: [ADSM-L] File serving with TSM for Space Management

2012-04-10 10:09:16
Subject: Re: [ADSM-L] File serving with TSM for Space Management
From: Paul Zarnowski <psz1 AT CORNELL DOT EDU>
Date: Tue, 10 Apr 2012 10:05:49 -0400
Thanks for everyone's feedback on my question.  Richard, your comments were 
just what I was looking for.  I'm looking at TSM/HSM and also an LTFS-based 
product from Crossroads Systems (Strongbox) that looks interesting.

If anyone is sharing an HSM-based filesystem via Samba, I'd like to hear your 
experiences on that.


At 05:02 AM 4/10/2012, Richard Sims wrote:
>On Apr 9, 2012, at 2:22 PM, Paul Zarnowski wrote:
>> Does anyone who is using TSM for Space Management (aka HSM) know if it can 
>> be used to share out filesystems using NFS (or CIFS)?  Or are there timeout 
>> problems that make this unworkable?
>You can, and we do it via NFS - but it can be a nightmare at times. Both HSM 
>and NFS operate as kernel extensions: any problems thus become very severe. We 
>had someone who thought it a good idea to have an HSM file system NFS-mounted 
>to an FTP server for data feeding. That resulted in a hung FTP server system 
>whenever data was being written faster than it could be migrated on the HSM 
>server. Over the past weekend we had a situation where a user thought it 
>reasonable to copy a movie file larger than the 64 GB HSM file system into 
>that area: the file system was wedged, and because it was NFS-served as well, 
>NFSd was hung; and the incoming files could not migrate because they were in 
>an open state, even after the writing process was killed off: we had to reboot 
>the server (which in turn somehow incited the failure of a IBM RAID adapter 
>card and a marathon recovery effort that I'm just recovering from). A little 
>known reality about HSM is that the space for a file must consist of 
>contiguous blocks: you can have an HSM file system that is like 85% full as 
>incited by a large file being written, and writing can proceed no further, 
>because the file system is fragmented. Because of this, for file systems which 
>get large files from users, we have an early morning job which forcibly 
>migrates everything out of the file system to maximize free space.
>But don't let me discourage you from using HSM...  :-)
>     Richard Sims   enduring at Boston University 

Paul Zarnowski                            Ph: 607-255-4757
CIT Infrastructure / Storage Services     Fx: 607-255-8521
719 Rhodes Hall, Ithaca, NY 14853-3801    Em: psz1 AT cornell DOT edu  

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