[rescue] Solaris filesystem overview, comparison to HP/IBM

[Andy Wallis]

On May 20, 2006, at 12:41 AM, Eric Webb wrote:

> We're about to purchase a few additional Sun systems at $work and I  
> need a
> refresher on Solaris disk/filesystems past and present.  The  
> particular
> application requires Solaris 9 for whatever reason, so I cannot  
> implement
> some of the newer stuff (ZFS) I've read about in Solaris 10.  We'd  
> like to
> end up with a Sol 9 environment with JFS reliability and LVM
> ease-of-management (including online filesystem resizing/expenasion.)


> I would appreciate any comparisons you can give to features of IBM  
> AIX (JFS +
> LVM) and HP-UX (vxfs + MirrorDisk/UX + Online JFS) that I am more  
> familiar
> with...  LVM versus slices/md.... JFS versus UFS versus whatever  
> else is
> available...
The AIX LVM is my favorite LVM because it is the most sane and  
easiest to deal with. It is very trivial to add another disk to a  
volume group and increase filesystem sizes on the fly. I love the  
fact that one could increase the filesystem while it was mounted and  
being written to.  I haven't run into the issue of hitting the  
physical partition count limit, but it does exist. One of the big  
disadvantages to AIX is that volume groups other than rootvg are not  
saved as part of a mksysb. We always run savevg commands to dump the  
rest of them to a tape after the rootvg backup record on a tape.

I'll state bluntly that the HP-UX LVM subsystem sucks royal donkey  
balls. One of my favorite pet peeves for it was that one had to hunt  
for an available major/minor number for a volume group.

Solstice DiskSuite doesn't have a concept of a volume group, but that  
could be faked through a large metadevice with soft partitions in  
it.  You can still grow filesystems while they are mounted (through  
metattach and growfs), but Sun makes it clear that the filesystem is  
read-only during the grow.  HP-UX, AIX, and Solaris all can put root  
into a logical volume. AIX is the only one to do it natively because  
all it deals with are LVs. It has no concept of a disk-based  
filesystem that is not controlled by LVM. I've haven't played with  
metaroot much in Solaris or HP-UX.

UFS with logging is close enough to JFS to be the same. The only  
difference is that Solaris doesn't have log commands to  
replay,reform, or delete a log during system recovery.

I haven't played with Solaris Flash archives, which came with Solaris  
8, so I can't speak to it for system restores with metadevices. We  
used a homegrown mksysb knockoff to backup and restore Solaris  
system. When I updated it for Solstice DiskSuite, I ran into a couple  
of errors that Sun would not fix until Solaris 10. The biggest was  
using metainit -a on a md.tab file to recreate a SVM environment.  
While the documentation said that it could be used, DiskSuite would  
not recreate soft partitions that were listed. The result was that  
you have to explicitly recreate each metadevice to insure a proper  
restore.

My workplace encapsulated the Solaris /var and /usr into slice based  
metadevices and created a nice RAID 1 to a second drive on SB100/ 
SB150 workstations and 280Rs. They worked nicely for either drive  
failed. Our architects fell in love with giving home grown  
applications their own metadevice filesystems rather than using  
quotas.  It became trivial to add space to fielded systems when log  
processing or system management tools needed more room for work.



> I remember that Sun added certain features (if not whole products,  
> like Disk
> Suite, no?) to previous Solaris releases... maybe Sol7 or Sol8...  
> and I'm
> curious to fill the voids in my historical knowledge.
Solaris 9 was when Sun took Solstice DiskSuite 4.2.1 (with the soft  
partition patch) and added it to the baseline OE. Previously, it was  
a costly add-on.  It was then renamed Solaris Volume Manager.  
DiskSuite 1.0 started back in the SunOS 4 days. I believe that Bill  
and some others used it back then.

Veritas is a very expensive LVM that I wanted to throttle because it  
can't be completely automated. We couldn't use it during our  
automated restores because it will not run at all without a valid  
license key. A reinstall even on the same machine would force you to  
call Vertias to relicense the machine. Imagine doing this for a test  
lab of 20-30 machines that would be reinstalled several times each  
shift to see how quickly our patience ran out with VxVM. Its  
installation is also very difficult to automate. The Sun Blueprint  
book for Jumpstart devoted an entire chapter to it as an example of  
installing troublesome 3rd party software in a Jumpstart session.

-Andy Wallis