Category Archives: Storage

How many VMs per DataStore should I have?

Although there are no steadfast rules for how many virtual machines should be placed on a datastore due to the scalability enhancements of VMFS-5, a good conservative approach is to place anywhere between 15-25 virtual machines on each.

The reasoning behind keeping a limited number of Virtual Machines and/or VMDK files per datastore is due to potential I/O contention, queue depth contention, or Legacy SCSI reservation conflicts that may degrade system performance.

This is why I suggest limiting your datastore size to 500GB-700GB each, because this helps limit the total number of virtual machines that can be placed on each datastore.

If you found this article to be helpful, please support us by visiting our sponsors’ websites. 

How to do a Firmware Upgrade on your Exagrid

Need to do a firmware upgrade on your exagrid? It’s a pretty straight forward process. The most difficult part is getting the download link for the firmware.
I have a link for version 4.6.4 here: http://supportweb.exagrid.com/downloads/software/4.6.4/4.6.4.P20/install.4.6.4.1038.P20.jar

After you have the firmware downloaded (it will be a .jar file), login to your Exagrid through Internet Explorer. Click “Manage” and “Software Upgrade”

From here, you can upload your downloaded file and Apply the file. A firmware update takes around 45 mins-1 hr.

You can view the upgrade in progress by refreshing the web page:
EX2

If you found this article to be helpful, please support us by visiting our sponsors’ websites. 

Reclaim “white space” – HP Lefthand SAN

Post from TeleData:

This is always one of the challenges (and limitations) to thin provisioning.

The technology used to provide thin provisioning in SAN/iQ is really more of a “high water mark”.Once a block has been marked as “written” you cannot recover unused space by deleting data from the volume. There is no communication facility in which the OS would “tell” the SAN that,
“Hey that block of data we were using yesterday, is now empty and you can have it back.”Since there is no way to “tell” the SAN the space is empty, those blocks of data, once written to cannot be reclaimed.

Your only option is to create a NEW volume, and migrate the data to the new volume, and then delete the old volume.

This can be challenging with direct native iSCSI mounted volumes, but if you are using a virtual machine (with virtual disks) you can reclaim storage by creating a new VMFS datastore, using sdelete to zero out unused space (within the Windows OS), then performing a storage migration and choosing “thin” provisioning on the virtual disk.

While still requiring a new (VMFS) volume, the virtualized disk can be left intact avoiding any reconfiguration within the Windows server itself.

The result would NOT be different if you had chosen thick vs thin. The blocks are still marked as used and a “high water mark” is still maintained. The only difference is when you mark it “thick” SAN/iQ reserves the entire space, and it cannot be used to provision to other volumes/snapshots.

This is why you can dynamically switch between thin and thick provisioning within the CMC.

If you found this article to be helpful, please support us by visiting our sponsors’ websites. 

How To Reset an EqualLogic PS SAN

1. Connect to the SAN via a serial cable to the active storage processor.

2. Enter the group login and password (grpadmin/grpadmin is default).

3. Enter the command “reset” and read the warning.

4. If you want to reset the SAN enter “DeleteAllMyDataNow”.

5. The SAN will then reset and reboot, ready for initial configuration.

If you found this article to be helpful, please support us by visiting our sponsors’ websites. 

Compellent and Java

For those that have used Compellent Storage Center web interface, you know that is requires Java 1.6 u18-38. Any other version has issues with the GUI.

As of yesterday, Oracle released a new Java update and it forces your browser to update to 7.x. Of course this update will cause interface issues with Compellent. We worked for 4 hours on this issue until we found that using an old version of IE 7 finally let us in without having to update to the latest Java release.

Bad on Oracle for forcing people to update. Good on them for trying to keep people secure.
Bad on Compellent for still requiring 1.6 Java Version. I don’t see a good side to this.

If you found this article to be helpful, please support us by visiting our sponsors’ websites. 

Compellent Dual Controller to Single Controller Conversion

I went on an install the other day and had a client try and upgrade from a Series 20-Dual Controller SAN to a Series 40-Single Controller Array. It was a test lab of theirs, and they didn’t feel like they needed an additional controller.

Turns out, you cannot do an “upgrade” like this. The client will need Dell to provide them a Single Controller License instead of the old Dual Controller License. And because you cannot upgrade, you have to setup the new Array like you would for a new client, and then do a Thin Import from the older Array.

Crazy, I know, but I guess that is how it has to be done.

If you found this article to be helpful, please support us by visiting our sponsors’ websites.