iSCSI FAQ

What is SoftLayer's iSCSI?


SoftLayer's iSCSI storage allows customers to access disk space on a high-performance iSCSI target. The storage is presented as a block-level device that customers can format to best fit their needs. iSCSI storage resides on the private network and all bandwidth to the iSCSI target does not count toward your public bandwidth allotment. 

iSCSI storage may be instantly added through “Add Other Service” under “Sales” in the Customer Portal.

Can I create and delete snapshots on demand?
Yes, snapshots may be created and deleted on command.
Can I create a schedule for snapshots to be taken?
You may create a schedule using a simple form method for basic details or an advanced form method for more details.
If I delete a snapshot schedule, will it delete all prior snapshots that were taken when the schedule was active?
No, when you delete a scheduled snapshot all prior snapshots created by that schedule will remain.
What happens when my snapshot space reaches its capacity?
When you snapshot space reaches its capacity, the oldest snapshot will be removed automatically by the system.  You will be notified via e-mail if an error occurs.
Can I mount a snapshot?
When a snapshot is placed online, it may be mounted at any time.
How do I make a snapshot mountable?
Snapshots are mountable as soon as they are placed online.  The option to enable online mode is available near the restore and delete options.
Does replication allow for a failover and failback option?

Yes, you will notice the options for failover and failback on the replication page within the SoftLayer Customer Portal.

Where can I learn how to mount or dismount an iSCSI Snapshot in Windows?

Microsoft provides documentation for Windows Server that contains instructions on mounting and dismounting iSCSI snapshots using Microsoft iSCSI Software Target. For more information, refer to Microsoft's Providing Local Access to Data on Virtual Disks page on TechNet.

What is an iSCSI LUN?

An iSCSI LUN represents a block-based storage device used to connect to your operating system. Once connected, the filesystem may be mounted for read/write access.

What is the difference between "failover" and "failback"?

Failover is the manual act of designating the Replica to the active copy of data. When "failover" is initiated, the LUN is no longer available on the operating system (OS) to which it is connected and the replica may be connected to the OS.

Failback is the manual act of returning active status to the LUN and making the Replica unavailable. The "failback" process is long-running, because any data changes applied to the Replica are copied back to the paired LUN.

It is important to note that only when a Replica is available may failover and failback methods be used.

What is a Replica?

A Replica is available for iSCSI LUNs that have replication purchased and configured. When replication is configured on an iSCSI LUN, a Replica exists as a remotely located, moment-in-time duplicate. The remote location for the Replica is called the Replica Site. By having both the LUN and Replica available for an iSCSI, failover and failback method may be used.

Can I use the replica LUN at a remote end while replication is in process?
No, replication is only one way.  You cannot use the LUN at the remote end at the same time that a replication is underway.
Can I restore my LUN from any of my snapshots?
Yes, all of your existing snapshots will remain and a snapshot will be created right before the restore.
Can I change the LUN name of my snapshots?
No, the technology that is in place does not allow for edits to the LUN name.  We recommend using the Notes section of your LUN to provide specific details to provide an additional layer of differentiation between LUNs.
Can I purchase snapshot space on a per-LUN basis?
Snapshot space may be purchased on a per-LUN basis.  Additionally, capacity may be upgraded at any time.
Can I replicate an iSCSI LUN to multiple remote locations?
Currently iSCSI LUNs may only be replicated to one location.
If an iSCSI LUN has been failed over to a remote location, can it be mounted and written to?
Yes, the remote LUN may be mounted and written to upon failback.  The changes which occurred after the failover can be synchronized to the main LUN.  This will start a process that replicates the entire LUN back unless you have purchased the ability to keep the latest replica on the local device.
Is LUN replication immediate?
The replication feature runs on a schedule and is not an immediate process at this time.
How can I tell which snapshot is using more space than another?
Snapshots utilize a copy-on-write technology with the main LUN, so there is no way to know exactly which snapshot is using more space.