Posts Tagged ‘VMware’

ESX/ESXi 3.5 Update 3 coming soon to an Akamai site near you?

October 28th, 2008

I doubt an upcoming release of ESX 3.5 Update 3 would surprise many people but has the company that rarely ever talks about futures let the cat out of the bag?  This page would seem to suggest so:


Connect a fibre attached tape device to a VM on ESX

October 27th, 2008

Have you ever considered virtualizing your tape backup server? Maybe you’ve thought about it in the past but reasoning produced drawbacks that were too compelling to go forth and virtualize. For instance, pinning a VM to a clustered ESX host which is connected with a SCSI cable attached tape device hanging off of it. Pinning a VM to a clustered host means you lose the benefit of a VM portability, you lose the flexibility of host maintenance during production cycles, and you lose the use of valuable dollars spent on VMotion, DRS, HA, shared storage, and FT (future).

What if you had the hardware to make it possible? Would you do it? If I had to purchase hardware to specifically make this happen, cost effectiveness would need to be researched. Everything else being equal, if I had the hardware infrastructure in place already, yes I would. I had access to the hardware, so I headed into my lab to give it a shot.

What’s required?

  • Hardware
    • One or more ESX hosts
    • At least one fibre HBA in each ESX host that supportes fibre tape devices (enabled in the HBA BIOS typically at POST)
    • A fibre attached tape device (the fibre HBA in a tape device is called an NSR or Network Storage Router)
    • At least one fibre SAN switch
      • If using more than one in a single fabric, be sure they are ISL’d together
      • If multipathing in separate fabrics, at least two HBAs per host will be required and at least two NSRs in the tape device (although this is really going overboard and would be quite expensive)
    • Fibre cable between ESX host and SAN switch
    • Fibre cable between NSR and SAN switch
    • Optional components: shared storage
  • Software
    • VMware ESX or ESXi
    • Virtual Infrastructure Client
    • Latest firmware on HBA(s), NSR(s), and SAN switch(es)
    • Appropriate zoning created and enabled on SAN switch for all ESX host HBAs and NSR
    • Optional components: VirtualCenter, VMotion, DRS, HA

The steps to setting this up aren’t incredibly difficult.

  1. Attach fibre cables between HBAs and SAN switch
  2. Attach fibre cable between NSR and SAN switch
  3. On the fibre SAN switch, zone the NSR to all HBAs in all ESX hosts that will participate. Be sure to enable the active zone configuration. On Brocade SAN switches this is a two step process.
  4. Perform a scan on the fibre HBA cards (on all ESX hosts) to discover the fibre tape device. In this case, I’ve got an HP MSL5026 autoloader containing a robotic library and two tape drives:
  5. Once each ESX host can “see” the tape device, add the tape device to the VM as a SCSI passthru device. In the drop down selection box, the two tape drives are seen as “tape” and the robotic library is seen as “media”. Take a look at the .vmx file and see how the SCSI passthru device maps back to VMHBA1:1:2 and ultimately the tape drive as a symbolic link:
    fctape2 fctape3 fctape9 fctape10 fctape11
  6. The VM can now see the tape device. Notice it is SCSI and not fibre. At this time, VMs only see SCSI devices. Fibre is not virtualized within the VMware virtual machines to the extent that a VM can see virtual fibre or a virtual HBA. The current implementation of NPIV support in VMware is something different and will be explored in an upcoming blog:

Good news! The fibre attached tape drive works perfectly using Windows ntbackup.exe. Effective throughput rate of many smaller files to tape is 389MB/minute or 6.5MB/second. As expected, running a second backup job with less files but larger sizes, I saw an increased throughput rate of 590MB/minute or nearly 10MB/second. These speeds are not bad:
fctape5 fctape6 fctape8

Now for the bad news. When trying to migrate the VM while it was powered on (VMotion) or powered off (cold migration), I ran into a snag. VMware sees the fibre tape device as a raw disk with an LSI Logic SCSI controller which is not supported for migration (I tried changing the LSI Logic bus to use Physical bus sharing, but that did not work):
fctape7 fctape9

The VM migration component of my test was a failure, but the fibre connectivity was a success. Perhaps we’ll have SCSI passthru migration ability in a future version of VMware Virtual Infrastructure. Maybe v-SCSI passthru is the answer (v-* seems to be the next generation answer to many datacenter needs). What this experiment all boils down to is that I can’t do much more with a fibre attached tape device than I can with a SCSI attached tape device. In addition, a VM with an attached SCSI passthru device remains pinned to an ESX host and therefore doesn’t belong on a clustered host.  However, I can think of a few potential advantages of a fibre attached tape device which may still be of interest:

  1. Fibre cabling offers better throughput speed and more bandwidth than SCSI.
  2. Fibre cabling offers much longer cable run distances in the datacenter.
  3. A failed SCSI card on the host often means a motherboard replacement. A failed HBA on the host means replacing an HBA.
  4. Fibre cabling allows multipathing while SCSI cabling along with the required bus termination does not.
  5. Fibre cabling leverages a SAN fabric infrastructure which can be used to gather detailed reports using native and robust SAN fabric tools such as SAN switch performance monitor, SANsurfer, HBAnywhere, etc.
  6. VMs with fibre attached tape can still be migrated to other zoned hosts by simply removing the tape device in virtual hardware, performing the migration, then re-adding the tape device, all without leaving my chair. A SCSI attached tape device would actually need to be re-cabled behind the rack.

ESX configuration script – display full path in COS

October 25th, 2008

MS-DOS old timers should appreciate this. I’ve been using this snippet for a few years in my ESX host deployment scripts.

ESX script to display the full path in COS


In your ESX console, instead of seeing this:

[root@host vmware]#

You’ll see this:

[root@host /etc/vmware]#

#Paste the following into PuTTY on your ESX host:

mv /etc/bashrc /etc/bashrc.old

sed -e “s/\\h \\\W/\\h \\\w/g” /etc/bashrc.old > /etc/bashrc

Close your PuTTY session and re-open to see the change take effect.

ESX –> ESXi Separation Anxiety

October 25th, 2008

For me, this topic could easily be part two in a series of many (Part one would have been my recent blog on ESXi partitioning). I’m an ESX guy. I grew up on the Service Console. But I must get familiar with ESXi. I firmly believe ESXi is the future and ESX will be put out to pasture. If you pay attention to what VMware has been saying lately, you’ll pick up the subtle hints. Maybe you have heard some of them:

  • Smaller hypervisors mean faster deployment times
  • Smaller hypervisors mean less code vulnerability, less risk to the environment, and less time spent patching the hypervisor
  • Smaller hypervisors can be embedded in server hardware
  • ESXi is free, lending itself well to rapid and wide spread implementation
  • Development efforts for scripting and automation are getting away from the Service Console (PowerShell, Host Profiles, Distributed Virtual Switch, etc.)

So my latest adventure in ESXi once again involved the “Tech Support Mode” console. I should really just stay out of there for my own good. Each time I go in there, I come out battered and bruised with more questions than I had going in. This time I was trying to troubleshoot an NPIV issue (future blog post). /var/log/vmkernel is what I wanted to take a look at but it wasn’t there. I searched the ESXi forums and found several hits referencing the vmkernel log and path validating my assumption that it did indeed exist in the spot where I was looking for it. Well, it doesn’t exist and the various posts in the ESXi forum referencing the existence /var/log/vmkernel are inaccurate, not to mention misleading. A quick conversation with helpful VMware employee dilpreet on the VMTN forums summed it up nicely:

All logging previously logged in vmkernel, vmkwarning is logged in /var/log/messages. There is no cron or dmesg log since they are not needed.

On that note, the supported method for viewing the Messages log is via the ESXi host console. Hit <F2>, enter the necessary credentials, choose the View System Logs menu option, and from the menu on the right, choose <1>. You get a forward and backward scrollable consolidated log file. For those who pride themselves on their grep or vi skills, your search capability has been reduced to simply hitting the </> key in the log viewer for RegExp Search.

I’ll get there eventually with ESXi. I’m just a little behind on the adoption and need to catch up with what others have already learned months ago. Admittedly, some of this is a pride issue.

Looking for VMware Tools?

October 25th, 2008

Are you looking for VMware Tools? Maybe just curious where they come from?

Look no further than your ESX host under /vmimages/tools-isoimages. There you’ll find the .iso files that mount as images into the virtual CD-ROM tray when the “Install/Upgrade VMware Tools” command is passed to the ESX host for a particular VM or group of VMs.

What else is in /vmimages? Browse to the floppies folder and you’ll find vmscsi- which is the optimized BusLogic SCSI driver for Windows guests. Although this driver will work for all Windows guest types, it’s best used with Windows NT and Windows 2000. Windows XP, Windows 2003, and beyond achieve better performance using the LSI Logic SCSI driver (which by the way can be downloaded from the LSI Logic website by following this link)

ESX partitioning a lost art form in ESXi

October 24th, 2008

On the heels of Duncan Epping’s blog article about ESX partitioning best practices comes my first look at the automatic partitioning in ESXi.

Before I dive into ESXi, allow me to provide a brief primer on the history of ESX partitioning as I see it. Once upon a time, long before the coming of ESXi and when there was only ESX, there existed great debates in books, whitepapers, knowledgebase articles, datacenters, forums, and blogs about how best to properly partition ESX. Careful planning up front meant better optimization, stability, and uptime of the ESX host, saving the company money from poor host performance, reduced downtime, and unplanned outages. The ESX administrator also slept better at night. What is the big debate? ESX administrators evolve from varying backgrounds where they dealt with a range of operating systems. Each administrator brings their best ideas, experiences, and nightmares the he or she would probably like to forget, to the table. With the ESX Service Console (Console Operating System or COS for short) based on a version of Red Hat, Linux and Unix administrators were natively the best equipped to carry on an intelligent conversation of Linux partitioning “Do’s and Don’ts”. However, ESX did add a few twists in how it used the COS and the file system. Taking into account the native behavior of Red Hat in addition to the ESX specific characteristics, partitioning best practices evolved. While not every administrator will agree on the exact size a given partition should be, a pattern in how ESX is properly partitioned is fairly evident, plus or minus the partition size variance that fits the personal taste of the administrator or perhaps company baseline policies or standards. ESX partitioning strategy was an art form; maybe something to brag about when getting your geek on in a circle of peers. I’ll go out on a limb here and say that no self respecting ESX administrator used the automatic partitioning ESX offered even though it might have saved a little time and in fact was and is still today the default partitioning choice during an ESX installation. No offense intended, but the automatic partitioning in ESX was less than stellar. In fact, automatic partitioning sizes were not consistent with best practices taught in the Virtual Infrastructure classroom training. Right there is a good a reason as any to partition manually.

Recently, I began evaluating ESXi. Having been a seasoned ESX administrator for quite a while, one of the things I noticed about the ESXi installation (in addition to its incredibly fast installation time) was the partitioning configuration. Or lack thereof. Had I blown through the screens so quickly that I didn’t notice and accidentally performed automatic partitioning? It was no accident. A second installation revealed that ESXi makes the partitioning choices for us, and provides us no opportunity to size our own partitions short of deleting and recreating after the fact using fdisk in the unsupported “Tech Support Mode” console. That’s nothing but trouble. The only partitions you should be creating after the ESX/ESXi installation are VMFS volumes.

So I’m stuck with automatic partitioning in ESXi. It’s a paradigm change I could get used to if it’s technically sound. But what does it look like and what are the partitions in ESXi used for? An unsupported trek into the “Tech Support Mode” console allowed me to run some df -h, fdisk -l, and ls commands to find out.

On an 8GB disk, an installation of ESXi 3.5.0 Update 2 creates the following partitions automatically:

Vmhba1:0:0:1 Extended

Vmhba1:0:0:2 FAT16 4,095MB Looks like /. contains directories: downloads, uwswap, var

Vmhba1:0:0:3 VMFS 3,347MB datastore for VMs, ISOs, VMKernel swap

Vmhba1:0:0:4 FAT16 <32M 4MB Unknown

Vmhba1:0:0:5 FAT16 48MB contains miscellaneous files (boot.cfg, *.tgz, etc.)

Vmhba1:0:0:6 FAT16 48MB contains miscellaneous files (boot.cfg, *.tgz, etc.)

Vmhba1:0:0:7 VMKcore 110MB allocated for VMkernel core dump

Vmhba1:0:0:8 FAT16 540MB contains directories: core (for COS dumps?), opt

Ok, some of the partition sizes above were quite small. Understandably, I started out with a small 8GB disk, not giving ESXi much to work with. My next question was “would the auto created partition sizes be larger if I used a larger disk?”. So I reinstalled using a 16GB disk to find out.

On a 16GB disk, an installation of ESXi 3.5.0 Update 2 creates the following partitions automatically:

Vmhba1:0:0:1 Extended

Vmhba1:0:0:2 FAT16 4,095MB Looks like /. contains directories: downloads, uwswap, var

Vmhba1:0:0:3 VMFS 11,539MB datastore for VMs, ISOs, VMKernel swap

Vmhba1:0:0:4 FAT16 <32M 4MB Unknown

Vmhba1:0:0:5 FAT16 48MB contains miscellaneous files (boot.cfg, *.tgz, etc.)

Vmhba1:0:0:6 FAT16 48MB contains miscellaneous files (boot.cfg, *.tgz, etc.)

Vmhba1:0:0:7 VMKcore 110MB allocated for VMKernel core dump

Vmhba1:0:0:8 FAT16 540MB contains directories: core (for COS dumps?), opt

Between the 8GB install and the 16GB install, not a single partition size change with the exception of VMFS. It simply grew the VMFS partition to consume the additional 8GB of disk.

With this automatic partitioning scheme, how heavily are each of the partitions utilized out of the box?

Vmhba1:0:0:2 FAT16 4,095MB 25% used

Vmhba1:0:0:3 VMFS 11,539MB n/a

Vmhba1:0:0:4 FAT16 <32M 4MB Unknown

Vmhba1:0:0:5 FAT16 48MB 0% used

Vmhba1:0:0:6 FAT16 48MB 76% used

Vmhba1:0:0:7 VMKcore 110MB 0% used (and let’s hope for the sake of uptime it stays this way)

Vmhba1:0:0:8 FAT16 540MB 32% used

Bottom line: Am I comfortable with this partitioning? Time will tell if it’s adequate. I’ll keep a watchful eye on the experiences of others on the VMTN forums. I’m not using ESXi in production or development right now. Further information gathering on ESXi may reveal there are other deployment methods for ESXi that allow more granular control of its installation parameters. For now, I’m in the evaluation stage to see if ESXi is the right fit. It certainly carries with it some attractive attributes but there are also things I must learn to let go of such as the Service Console and all of the utility it provides.

The Lab – Then and Now

October 19th, 2008

I’ve completed a new blog page:

The Lab – Then and Now
A gallery documenting its evolution using VMware

To visit, just click the “Lab” menu item at the top of the page.