Solaris Volume Manager - a brief history
By user12610379 on May 16, 2005
There are some who jump onto things quickly. I am not one of them. I still run Solaris 8 (x86) on my Pentium III at home overclocked to 660 Mhz. My other machine is a ferrari running Solaris 10. (Whew..I was wondering how I could stick in that bumper sticker line.) Blogging by my standards is new and I could have waited for another couple of years before I jumped onto this bandwagon. However, recently I have been answering questions on the opensolaris discussion group that I thought would be useful to for a larger audience. What better way then to blog and so with much trepidation, I have decided to blog. I work on the Solaris Volume Manager and have been at it for a while. Since the first blog is like those awkward dance steps, I thought I might talk about something that I am very comfortable about; the history of Sun's Volume Manager
It started out as OnlineDiskSuite or ODS(thank marketing for naming a product that sounds like odious). It was later renamed to Solstice DiskSuite or SDS. SDS was enhanced to included a newer meta database and RAID-5. Disksets for clustering was also introduced. SDS lived through versions 4.0 through 4.2.1. The last version is supported on Solaris 8.
With the growing popularity of Solaris we felt that the volume manager should be an integral part of the operating environment. For the user this would provide seamless upgrades(and live upgrades). No need to tear down and rebuild the volume configurations anymore. It also avoided the annoyance of figuring how to obtain a volume manager. When you loaded Solaris it was there..just like the file system. There are advantages for us too. The integrated volume manager can automatically benefit from other enhancements in the kernel. For all these reasons the volume manager became part of Solaris 9. To clearly delineate this phase, the volume manager was renamed to Solaris Volume Manager or SVM for short. SVM does not have separate versions...just like the file system (UFS) does not have separate versions.
The big change between SDS and the integrated Solaris Volume Manager
is the use of device ids for tracking disks. The word device ids I
is a Solaris term. But its basis is in WWN. All modern disks have a
identifier. SCSI and FC drives use WWN (World Wide Numbers) as defined
the SCSI spec. IDE/ATA disks use a different scheme but they too are
unique. By using devids to track disks, we addressed a big customer
Volume numbering would not be lost even when disks get renumbers.
if drives were renumbered, the SDS configuration would be lost. This
because SDS used the major/minor numbers to track the configuration.
minor numbers could change for a variety of reasons. If one moved a
controller from one slot to another, the device enumeration would
which in turn would change the minor number. Now one can really shuffle
drives and SVM will not only find it and construct the metadevices
correctly, but it will also update the drive names so that the user has
correct information. Since Solaris 9, new functionality has been
delivered in various Solaris 9 updates while also incorporating these
features in Solaris 10. So what does SVM deliver now ?
- Support for Multiterabyte volumes
- Improved integration with Dynamic Reconfiguration
- Metassist - a high level command that assists users in creating volume
- Support for CIM/WBEM
- Diskset mobility - the ability to import diskset
- Support for cluster volume manager
These are just the highlights that encompass a number of smaller features.
Now that I have jumped headlong into blogging..there is no turning back!!