There's no such thing as 'in general' it depends on your requirements. iSCSI isn't an internal storage mechanism - that is it's not how you'd link a disk directly inside a server, it's slow and needlessly complex for such a job where SATA or SAS would be far better.
In terms of speed iSCSI works at whatever the interface is so typically 100Mbps, 1Gbps and 10Gbps - equating to ~10MBps, 100MBps and 1GBps though only if the actual disk array can keep up and the controller/s aren't too busy serving other requests.
Now onto whether it's right for you, the first thing to know is that iSCSI is block-level storage, it's up to the client machine's file systems (which obviously varies based on OS) to mount, partition, format and manage this block-level storage. Most filesystems aren't cluster-aware meaning that they can't share this data with any other machine/s unless they're all using the exact same cluster-aware file system. This is an important distinction, as some software requires block-level storage. The other main block-level storage system is Fibre-Channel which uses a dedicated network, usually at 1, 2, 4 or 8Gbps but usually has far less network contention that iSCSI.
iSCSI is not a NAS file system which allows for file-level sharing such as NFS, CIFS/SMB, HTTP, FTP/SFTP etc.
So if all depends on what you're trying to achieve - let us know and we'll be able to help you better.
There's no such thing as 'in general' it depends on your requirements. iSCSI isn't an internal storage mechanism - that is it's not how you'd link a disk directly inside a server, it's slow and needlessly complex for such a job where SATA or SAS would be far better.
In terms of speed iSCSI works at whatever the interface is so typically 100Mbps, 1Gbps and 10Gbps - equating to ~10MBps, 100MBps and 1GBps though only if the actual disk array can keep up and the controller/s aren't too busy serving other requests.
Now onto whether it's right for you, the first thing to know is that iSCSI is block-level storage, it's up to the client machine's file systems (which obviously varies based on OS) to mount, partition, format and manage this block-level storage. Most filesystems aren't cluster-aware meaning that they can't share this data with any other machine/s unless they're all using the exact same cluster-aware file system. This is an important distinction, as some software requires block-level storage. The other main block-level storage system is Fibre-Channel which uses a dedicated network, usually at 1, 2, 4 or 8Gbps but usually has far less network contention that iSCSI.
iSCSI is not a NAS file system which allows for file-level sharing such as NFS, CIFS/SMB, HTTP, FTP/SFTP etc.
So if all depends on what you're trying to achieve - let us know and we'll be able to help you better.
I use iSCSI for SAN backed Clusters; works great, but if you're getting 1MBps, something's probably wrong. The SAN I use daily does 120MB+ sustained.