Configuring FreeNAS for backup of data on ESX VMs

[ttblum]

Hello,

I currently have a Windows server running a tape backup (Backup Exec) that is starting to become overwhelmed by backup data being written to it over CIFS shares - I have several ESX hosts running VMs that are writing database backups to it over CIFS.

I plan on adding a server running FreeNAS to hold the database backups, the new server using regular spinning drives, and adding more drives as I am able to get them.

Would I configure to host iSCSI storage for this? If so, would physical Windows servers be able to access the data if the storage was formatted VMFS? Would I consider using iSCSI MPIO?

I read that NFS is much slower without an SSD for ZIL intent log, is this true is this situation?

 

[elangley]

My 2 cents worth:

If you want the most flexibility configure a volume and share it via NFS and CIFS. This way you can mount the volume with either vSphere, Linux or Windows.

Yes, NFS is slower but as you mentioned using an SSD speeds up the write cache. I use this method and it works. iSCSI is faster because it does not use the copy on write method, reducing the data integrity capabilities of ZFS.

If data integrity is not an issue for you can disable sync on a per volume basis which eliminates the need for the write cache [read all of the warnings about this prior to making this decision];

"In latest ZFS (version 28) the vfs.zfs.zil_disable loader tunable was replaced with the "sync" dataset property. You can now enable/disable ZIL on a per-dataset basis.

zfs set sync=disabled tank/dataset "

Set the backup volume to use lz4 compression. It's block level and saves a ton of space, especially for bulky backups. I see about disk consumption 35-40% savings.

Consider looking Veeam to backup the vSphere hosts and using FreeNAS storage for the backup files. Other backup options include Trilead VM Explorer, StorageCraft, etc.. These methods gives another option to restore a corrupted virtual machine in it's entirety, along with quiesced file level SQL backups, etc..

Lastly you can take Periodic Snapshots of your backup volumes and replicate them to other FreeNAS units either locally or off-site.

Hope this helps.

~eric

 

[jgreco]

]iSCSI is faster because it does not use the copy on write method, reducing the data integrity capabilities of ZFS.

That's just completely wrong.

 

[elangley]

Sorry, I did not reference the thread where I had read that and cannot locate it right now.

The thread was a long discussion about the problems with vSphere performance over NFS vs iSCSI, with iSCSI being much faster than NFS due to [some] difference.

If that is not the case so be it.

I still prefer NFS over iSCSI for simplicity and easier access to the volume, from vSphere, Linux or Windows. You just have to get it to write fast enough, ideally with an SSD, which is what I recommend.

 

[jgreco]

iSCSI is about the same speed as NFS if sync is set correctly (or if both are set incorrectly). NFS defaults to sync while iSCSI defaults to async.

As you note, NFS is more convenient than VMFS on iSCSI for admin access to the VM files.

 

[elangley]

iSCSI is about the same speed as NFS if sync is set correctly (or if both are set incorrectly). NFS defaults to sync while iSCSI defaults to async.

Ah, so there is the difference. iSCSI is faster than NFS in FreeNAS "out of the box" since sync is disabled.

~e

 

[jgreco]

In the same way that CIFS is faster than NFS if you forget to turn it on. One thing being faster due to incorrect configuration is probably a poor comparison.

 

[ttblum]

Ok.

Are there any situations where iSCSI MPIO would be a better choice than NFS with LACP or Load Balancing Aggregation?

Which would be better in this case, where many servers are backing up to the FreeNAS: NFS with LACP, or, NFS with Load Balancing Aggregation?