SAM-FS atop ZFS.

SAM-FS/QFS and ZFS can logically live hand in hand. We have exercised the abilities and capabilities of ZFS for disk based archiving as a means to drive forward the flexibility of SAM in high throughput, high file-change-ratio environments. This document explains how such a configuration was attained.

 In principle, disk based VSN staging within SAM-FS/QFS client environments can come from any filesystem under Solaris control. It can even come from iSCSI targets/initiators mapped into the host, or NFS mounts. On the surface, it would seem obvious to use a QFS filesystem, or a UFS filesystem for disk based VSN staging. If we think about what is possible however, ZFS makes more sense. Some of the functionality one can achieve with disk based VSN pools for SAM archives include:

• On the fly bz2 compression r/w from the target filesystem:

[root@bigsamhost1:/] $ zfs get compressratio
NAME         PROPERTY       VALUE        SOURCE
specialarch  compressratio  8.84x        -
archive1     compressratio  1.20x        -
archive2     compressratio  1.18x        -
samfs        compressratio  1.00x        -
space        compressratio  1.04x        -

• Seamless failover between redundant sites using "zpool export/zpool import" commands represented in SMF

• Zero bit-rot/RAID write hole possibility

• Scrubbale volumes, for SHA1/MD5 sum generation and regular checking (no fsck here!

• Stager/archiver performance in excess of the maximum extents that a fabric will allow, provided you have the spindles to allow for such aggregated I/O

• The flexibility of having only a software layer to worry about under management, and hot a hardware RAID controller, additionally

 In order to achieve simple zpool configuration for disk based VSN staging, one should edit /etc/opt/SUNsamfs/diskvols.conf putting in the archive filesystem name, then the mount point, as follows in an example:

[root@bigsamhost1:/] $ cat /etc/opt/SUNWsamfs/diskvols.conf 
archive1 /archive1      
archive2 /archive2
specialarch /specialarch

 As with all progressive filesystems, with every release of OpenSolaris comes new functionality to ZFS, with block level deduplication being considered as the next logical step. With such power and functionality, SAM can be best put to work atop ZFS.