Feasibility questions

[indianaviking]

   

Hi,

 

I have a small business client with a few VMWare VMs (probably 4 when it's all said and done).  We would like to implement off-site storage of their VMs, and the Terastation III looks like it might do the trick.  Here's the conecpt.

 

1. Hot Clone the VMs to a TeraStation III.

2. Have the Terastation do a nightly backup to an attached USB disk.

3. Rotate the USB disk nightly.  Perhaps have 5 disks, one for each day of the week. 

4. Move USB disk off site.

 

questions:

- what file format does the TeraStation III use for external USB drives?  EXT3 would be ideal.  I found some evidence that the TeraStation II only used XFS, is that still true with the III?

 

- If we use iSCSI and format a LUN with VMFS, can the TeraStation backup that data to an external USB Drive?  If not, NFS would suffice, though it's a bit slower.  Would save a few bucks too.

 

- How is the write speed on the external USB drives?  The total size of the VMs would be about 500 GB, which should take about 4 hours to copy if USB write speeds are 300 mbps.

 

- With the external USB Disk Rotation, can the TeraStation first wipe out any data on the drive before performing the backup?

 

- What issues might we come across by swapping out the USB disks on a daily basis?  Would this break a scheduled backup if a different external drive is present?

 

- I see there are two USB ports.  Can two backups occur at the same time?  Would there be a performance hit?

 

- If we were to get a 2nd TeraStation, I do see there is a replication feature that will only copy the changes.  Is this feature any good?  Does it compress before sending?  If we have a daily data delta of 1GB, how long would that take to replicate over a frac T1 (512k)?

 

- Is this stupid?  It seems like a cost effective solution considering other contraints on the project. (original idea was to use vReplicator to clone VMs across a WAN link, but the WAN link is too unreliable and slow for this to work consistently..so I imagine the same would hold true for TeraStation replication...)

 

thanks in advance...

[indianaviking]

   

Also, are e-mail alerts available, i.e. to notify if a scheduled job fails?

 

I read some reviews, and it seems NFS and backup to USB speeds are lacking.  Perhaps the reviews were older, and updated firmware has addressed these issues?

 

 

[Colin137]

-- what file format does the TeraStation III use for external USB drives?  EXT3 would be ideal.  I found some evidence that the TeraStation II only used XFS, is that still true with the III?

 

EXT3 or XFS.

 

- If we use iSCSI and format a LUN with VMFS, can the TeraStation backup that data to an external USB Drive?  If not, NFS would suffice, though it's a bit slower.  Would save a few bucks too.

 

The iSCSI Terastations do not support backing up to a USB drive. The standard Terastation III can back up to USB drives, and will support NFS. (Make sure you have the latest firmware if you plan on using NFS with VMware.

 

- How is the write speed on the external USB drives?  The total size of the VMs would be about 500 GB, which should take about 4 hours to copy if USB write speeds are 300 mbps.

 

Doing a normal backup (not differential) will run close to the max of the USB drive attached... USB drives are usually limited to around 20-30 MB/s due to spinal and seek speed.

 

- With the external USB Disk Rotation, can the TeraStation first wipe out any data on the drive before performing the backup?

 

Not automatically. You would have to format it from the web gui. Also, make sure to unmount the USB disk after backing up to it... use the function button, or in the gui go to System->Storage, click on the USB disk, and click Remove.

 

- What issues might we come across by swapping out the USB disks on a daily basis?  Would this break a scheduled backup if a different external drive is present?

 

Honestly, I'm not sure. I believe that as long as you unmount the USB disk before swapping it, it should work like that.

 

- I see there are two USB ports.  Can two backups occur at the same time?  Would there be a performance hit?

 

2 backups at once is definitely not recommended. There would be a fairly large performance hit.

 

- If we were to get a 2nd TeraStation, I do see there is a replication feature that will only copy the changes.  Is this feature any good?  Does it compress before sending?  If we have a daily data delta of 1GB, how long would that take to replicate over a frac T1 (512k)?

 

That's probably not the best idea to do over a WAN connection. I would recommend just using a backup job for that, instead of replication. You can enable transport compression on the backup jobs. Keep in mind, the destination Terastation would need to have it's own public IP address... it won't work right through NAT.

 

- Is this stupid?  It seems like a cost effective solution considering other contraints on the project. (original idea was to use vReplicator to clone VMs across a WAN link, but the WAN link is too unreliable and slow for this to work consistently..so I imagine the same would hold true for TeraStation replication...)

 

Your assumptions are mostly sound, but obviously it needs to be tested in your specific environment before you'll be able to tell if it's right for you.

 

-- Also, are e-mail alerts available, i.e. to notify if a scheduled job fails?

 

Yes. Limited support for SMTP authentication is there, but again, test it to make sure it works with your email server. Most SMTP servers are somewhat quirky.