What Does Sun StorageTek Storage Archive Manager Do ?

You can get a nice marketing overview of the value of SAM here.

Digging a little deeper: from an application's perspective a SAM file system behaves like a standard UNIX file system, but under-the-hood it has Hierarchical Storage Management (HSM) features quietly securing your data; moving it between storage tiers based on a custom rule set.....

Life Cycle of a File in a SAM File System

Create: File is written into the SAM file system.

Archive: A file is archived (copied) after a period of time, called its archive age, to archive devices. These can be a directory in a local file system (called a disk archive) or removable media (typically tape devices). Up to 4 copies of a file can be made and they can be made at different times to different archive destinations. e.g. make Copy 1 after the file has been in the file system for 60 minutes, Copy 2 after 120 minutes. If a file is modified after it has been archived then we make new copies of it. As well as age, there are a number of other parameters which can form the Archiving Policies which determine when a file or files are archived; but essentially archiving is a continuous process, there is no backup window for a SAM file system, it takes care of itself.

Release: If the % full of a SAM file system passes a high watermark (e.g. 80% full) the data blocks of the oldest/least recently accessed files are automatically released from the cache until the low watermark (e.g. 70% full) is reached. SAM is often configured to only partially-release files i.e. leave the first N KB behind as a stub, this is so that applications like file managers can scan the first few KB of a file to find out what it is. SAM Policies can be configured so that a file cannot be released (ever), or not release until all of the required copies of the file have been made. Once a file has been released it is often referred to as being off-line.

Stage: The process of bringing a released file back from the archives to the file system is called staging. Disk archives normally stage the file back very quickly, but if the data blocks are coming from a tape archive a worst case delay in the order of minutes can be expected and the application reading the file must be tolerant of that, or its files should never be released.

Unarchive: Copies of a file can have an unarchive age set. e.g. unarchive Copy 1 of a file if it has not been accessed for 6 months. This means that if the file was later opened, Copy 2 would have to be read. This feature can be used to initially archive a file on to disk or fast tape and to later free the space on that media leaving a copy or copies on slower/cheaper media.

Re-cycle: Optional step to re-cycle space from the archives by removing deleted and unarchived files and old versions of files.

Sharing a SAM File System over NFS and CIFS

As well as accessing it locally, you can share a SAM file system using NFS and CIFS (via SAMBA)....

SAM Overview

The only requirement for NFS is that the NFS Client supports correct handling of the NFS3ERR_JUKEBOX error code: if it does not then problems can occur when off-line files are opened as the NFS client will not understand that the file is off-line, and if it is slow to come online (i.e. the file is on tape) NFS may timeout.

SAMBA is a local application so far as Solaris and SAM are concerned; as such, SAMBA will wait for off-line files to come back online just as any other application running locally to SAM would and so, indirectly, CIFS clients must wait for the file to come online also.

SAM Management

Managing SAM used to require a lot of work on the command line: now the File System Manager ships as standard with SAM and provides an easy to use UI from which you can manage all aspects of your SAM environment...but you can still use the command line if you prefer it :-).

File System Manager

SAM: Easy Access to Tiered Storage

Given the features of SAM and its ability to be shared to network clients, we have an easy way for applications to access a Tiered Storage Environment.

SAM elegantly solves the problem of backing up file systems storing very large numbers of files, continuously archiving the file system's content as it changes..and in event of hardware failure, SAM file system recovery processes are very quick and efficient also.

Once a file is archived, we are done...we don't make copy after copy of the unchanged file as a conventional backup product would as it works through a cycle of daily/weekly/monthly backups...so we use less tape and secondary storage.

These features makes SAM of particular interest when working with Archiving & Enterprise Content Management (ECM) applications. These create huge volumes of data in the form of files which are probably not going to change once written, but need to be stored safely for long periods of time. I will be writing about work that I have done in this area with SAM and the Sun Fire X4500 in a future posting.


I know you can present a ufs filesystem over ZFS. Does SAM work on top of ZFS? Does it make sense to do that?



Posted by Scott on September 15, 2007 at 12:07 PM BST #

Hi Scott. SAM cannot archive data out of a ZFS file system, but a SAM file system can be built on a ZFS Volume. One possible configuration on a Sun Fire X4500 is to build one big storage pool, create a ZFS Volume for a SAM file system and share it via SAMBA (or NFS). Use the rest of the storage as a ZFS based disk. Throw data into the archive and have SAM take copies of it to the disk archive and also to tape. What you get is a "bottomless archive" as SAM will manage itself so that it never overflows assuming that the amount of data flowing in does not overwhelm SAM's ability to archive it and release it. I just finished testing a configuration like this with Symantec Enterprise Vault and it archived at 90,000 items an hour (items were 400,000 small files 60K->100k). Rgds, Tim

Posted by Tim Thomas on September 18, 2007 at 05:03 AM BST #

what about on-disk encryption of SAMFS?

will zvol/zfs ever have this?

Sun Cluster SAM-FS/Zvol/ZFS/SAMBA? Is this supported?

QFS can be thrown in anytime?

sorry for the onslaught!


Posted by will on October 29, 2007 at 08:01 PM GMT #

Hi Will, I can only comment on what is available now. So, SAM does not support on disk encryption and ZFS does not have native archiving. You can build a SAM file system on a ZVOL, that is supported. I believe that you can go from a standalone SAM file system to a shared one quite easily so far as keeping the data in place during the "upgrade" As for the Cluster question, ZVOL support for SAM is really new so I would imagine that the answer is no..but you best contact whoever you buy you Sun hardware & software from for a definitive answer. Thanks, Tim

Posted by Tim Thomas on October 31, 2007 at 03:44 AM GMT #

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