#!/usr/local/bin/bash

# Path to ZFS executable:
ZFS=/sbin/zfs

# Parse arguments:
TARGET=$1
SNAP=$2
COUNT=$3

# Function to display usage:
usage() {
    scriptname=`/usr/bin/basename $0`
    echo "$scriptname: Take and rotate snapshots on a ZFS file system"
    echo
    echo "  Usage:"
    echo "  $scriptname target snap_name count"
    echo
    echo "  target:    ZFS file system to act on"
    echo "  snap_name: Base name for snapshots, to be followed by a '.' and"
    echo "             an integer indicating relative age of the snapshot"
    echo "  count:     Number of snapshots in the snap_name.number format to"
    echo "             keep at one time.  Newest snapshot ends in '.0'."
    echo
    exit
}

# Basic argument checks:
if [ -z $COUNT ] ; then
    usage
fi

if [ ! -z $4 ] ; then
    usage
fi

# Snapshots are number starting at 0; $max_snap is the highest numbered
# snapshot that will be kept.
max_snap=$(($COUNT -1))

# Clean up oldest snapshot:
if [ -d /${TARGET}/.zfs/snapshot/${SNAP}.${max_snap} ] ; then
    $ZFS destroy -r ${TARGET}@${SNAP}.${max_snap}
fi

# Rename existing snapshots:
dest=$max_snap
while [ $dest -gt 0 ] ; do
    src=$(($dest - 1))
    if [ -d /${TARGET}/.zfs/snapshot/${SNAP}.${src} ] ; then
	$ZFS rename -r ${TARGET}@${SNAP}.${src} ${TARGET}@${SNAP}.${dest}
    fi
    dest=$(($dest - 1))
done

# Create new snapshot:
$ZFS snapshot -r ${TARGET}@${SNAP}.0

From the command line, call the script something like the following:

./zfs-snapshot.sh tank weekly 5

This would take a recursive snapshot of the “tank” zpool with the basename weekly, rotating through five snapshots with names “weekly.0″ through “weekly.4″. This allows you to implement a snapshot scheme approximately similar to NetApp’s hourly-daily-weekly scheme, if you like. Because my FreeBSD workstation isn’t on 24×7, I run hourly snapshots out of /etc/crontab:

# Automated ZFS backups (hourly):
0 * * * * root /root/bin/zfs-snapshot.sh tank hourly 25

And daily/weekly/monthly snapshots out of /usr/local/etc/anacrontab (from the sysutils/anacron port):

PATH=/bin:/sbin:/usr/bin:/usr/sbin

# days		make sure the command is executed at least every 'days' days
# delay		delay in minutes, before a command starts
# id		unique id of a command

# days	delay	id		command
1	5	daily		periodic daily
1	10	daily_snap	/root/bin/zfs-snapshot.sh tank daily 8
7	15	weekly		periodic weekly
7	30	weekly_snap	/root/bin/zfs-snapshot.sh tank weekly 5
30	60	monthly		periodic monthly
30	90	monthly_snap	/root/bin/zfs-snapshot.sh tank monthly 13

(Of course, this isn’t as cool as the Gnome-integrated Time Slider in OpenSolaris, but it scratches my itch sufficiently.)

As I noted in my “quick walk” post‘s comments, I had difficulty getting LDAP working initially on my corporate Active Directory network. The crux for me turned out to be getting the LDAP Schema Definitions correct. Here are the settings that worked correctly for me, authenticating against an AD instance with the schema extended by Microsoft’s Services for Unix add-on (other LDAP schemata will, of course, need different mappings):

USERS
Search descriptor: Don’t leave this blank – according to the Fishworks documentation this “sets the LDAP search descriptor, attribute mappings and object class mappings for users and groups. By default, the search descriptor for users is ou=people,dc=example,dc=com, and for groups is ou=group,dc=example,dc=com” – so what you enter will be site-specific.

Attribute mappings:

• uid=msSFU30Name
• uidNumber=msSFU30UidNumber
• gidNumber=msSFU30GidNumber

Object class mappings:

• posixAccount=User

GROUPS
Search descriptor: Again, don’t leave this blank – enter the appropriate value for your site.

Attribute mappings:

• gidNumber=msSFU30GidNumber
• uniqueMember=msSFU30PosixMember

Object class mappings:

• posixGroup=group

How did I know that the schema definition mappings were the problem? The logs gave it away: Maintenance -> Logs -> System, where I saw messages similar to the following: “libsldap: Status: 0 Mesg: Unable to set value: schema map already existed for ‘User’.”

How did I know that I had the schema definitions working? Share settings that I had created using numeric UIDs and GIDs automatically became mapped to the correct user and group names.

I’ll update this post if I find additional configuration that may be necessary.

That was easy...

Below is a quick walkthrough of my experience booting and installing the Fishworks VMware appliance; my thoughts follow.

Fishworks Boot Screen

Initial network configuration

Yes, Virginia, there is a command line - but not a conventional shell

Web interface login screen

Network configuration

Configure DNS - pretty basic stuff

NTP is a good thing

Name service configuration choices

Active Directory integration for CIFS shares is straightforward

Fishworks phone home...

Storage configuration made fast and easy

All done!

Thoughts: First off, as a VMware appliance and an introduction to Fishworks, this virtual machine is extremely well done; it gives users a low “activation energy” method to try out Fishworks. There’s a lot more effort involved getting a sixty-day loaner from Sun, as neat as that program is – even the logistics of racking and cabling the machine are relatively expensive in terms of time, after all. Of course, there are limitations inherent to a virtual machine; for example, I’d love to see how VMware ESX performs using a hybrid storage pool, but only real hardware can answer that. However, for most of my questions about Fishworks, the VM fits the bill.

Once you hit the VM’s virtual power button, it boots up quickly – faster than most OpenSolaris machines, subjectively – and the initial configuration is straightforward. Although I didn’t try it, it does appear that the machine can be completely configured from the command line, either at the console or over SSH. Once the system is configured, you have HTTPS or SSH remote administration access; however, SSH does not give you a standard Solaris shell, such as sh or bash. Instead, you get an interface very similar to Solaris’ zonecfg – a command line interface with multiple modes. (I suspect that a shell can be launched on the machine somewhere, somehow – it may even be documented – but I wouldn’t be stunned if it’s “unsupported.”)

The six-step configuration process via the web interface is smooth and consistent, and not particularly time-consuming – you get this sense that this is truly intended to be an appliance. My only complaints: The online docs were not immediately helpful (seriously – links to Wikipedia?), and when something does go wrong, you don’t get much more immediate help than this:

Uh-oh - how do I get to those log files?

By far, the best part of the configuration interface is step six – the storage configuration. You see a list of your configuration choices, with availability, performance and capacity rated. The left-hand column shows a pie-chart breakdown of your storage utilization, with the tiny “Reserved” slice surely being a jab at NetApp. (Well, maybe not – but as a NetApp user, it sure got my attention.) Simply pick your RAID type, click “commit” and you’re on your way. Genius.

All in all, very impressive. Makes me wish even more that I had a pair of 7410s to put behind ESX. And Exchange. And SQL Server. And my CIFS and NFS users… you get the idea.

• Amazon Elastic Block Store goes live! (Yeah, that link’s dead – like I said, it was later deleted.) The RightScale folks appear to have inadvertently published a draft (on 8/8, the day after I left town) of their blog post designed to coincide with the release of Amazon’s Elastic Block Store for EC2. They later deleted it, but Google Reader kindly cached the post for me. I won’t repeat anything in the post, nor would I bank on anything written there – would you gamble anything important on a retracted post about a not-yet-released product? I will add one comment: Will EBS attract attention of the lawsuit kind from NetApp? (I mean that comment only partially in jest – and you’d probably have to have seen the original post to know what I’m talking about.)

• NetApp finds NAS could mean ‘never accessed storage’ – “According to a USENIX presentation, 90% of data on NetApp’s networked storage systems was untouched over a 3-month period, raising the issue of whether it would be better placed on cheaper storage.” I would find some irony in that cheaper storage being tape.
• zfs un-benchmarking – “Our rationale for testing was to finally get some numbers that we can provide to users/customers about real zfs performance. There is a huge amount of (largely uncontested) information (emanating mainly from Sun and its agents) that zfs is a very fast file system. We want to test this, on real, live hardware, and report. Well, we can’t do the latter due to Sun’s licensing, but we did do the former. Paraphrasing Mark Twain: ‘Rumors of zfs’s performance have been greatly exaggerated.’” When Joe Landman blogs about performance, I take what he has to say seriously, but given the stability problems he notes, I wonder if – as he suggests – that driver issues are a factor here, and we’re not seeing a generic ZFS issue. (Seen at InsideHPC.)
• Self-protecting archive for SharePoint – “A new archiving product from BridgeHead Software automatically moves older, infrequently-accessed SharePoint items to cheaper archive media and cuts down the SharePoint backup burden.” HSM for SharePoint, apparently? Sounds interesting.
• Since NFSv4 is Stateful It Must Be Less Robust, Right? – “The short answer is no.” Interesting summary of how locking works under NFSv4; although I haven’t used NFSv4, this sounds like a massive improvement over previous versions – can I get the time that I spent debugging locking problems on Linux NFS servers back now?
• Storage Opens Up – Sun releases new JBODs and upgrades Thumper’s hardware. Given that I heard rumors of the Thumper expansion shelves (J4500) maybe a year ago, I’m surprised it took them so long to come out. And is it just me, or do the J4200 and J4400 look a little like someone else’s boxes rebranded?