Hi guys,

I recently came in contact with Open-E iSCSI servers and decided to improve my knowledge about this topic so I can set up my clients with iSCSI storage server installations. I got myself an iSCSI Enterprise R3 IDE device and will shortly buy a dedicated system for it (8 drives, 3ware RAID controller...)

Since I am new to iSCSI and its features, I have some rather (I hope) easy to answer questions. Here we go:

1. Hardware: For a well performing iSCSI storage server (well enough to build a client SAN and edit broadcast video - perhaps even HD) capable of bonding up to 4 Gigabit channels (802.3ad with an Intel 1000MT quad port card), I plan on buying an Intel board for socket 775 cpus, add an Intel Core2Duo ~2,4 GHz and 2 gigs of ECC RAM. Looking at RAM pricing these days I wonder if I would benefit from installing more RAM? 4 gigs? 8 gigs? Is this a good idea or do I need to get a multicore Xeon system? Should I go with the new 9650 PCIe RAID controllers by 3ware or should I stick to the 9550 PCI-X version?

2. Online capacity expansion. I understand I can expand the capacity of an existing RAID set with a 3ware controller without having to copy files by adding one disk after another. How will this work with my iSCSI target? Will it discover and display the added capacity?

3. I read somewhere that if I set up a volume and access this one volume from multiple initiators, I will get data corruption, so I need to set up each initiator with its own target. Is this true? I guess only when accessing the same file from multiple initiators. How will I be able to use my iSCSI system as a SAN for multiple client workstations in video postproduction (like Apple Xraid with Xsan?)

4. Is there some sort of idle shutdown for a mounted volume? Will energy saving settings affect the volume when they try to spin down the iSCSI volume?

5. Snapshots. I don't get it. Why is there a time window for a snapshot, not just a single time where a snapshot will be made? I understood snapshots as working like this: I put my original files on the volume and activate snapshots. All changes to my original files will be stored in the snapshot area of the iSCSI target, so if someone messes up and deletes a file or changes a database, I can mount the snapshot share and recover the original.

Example: The snapshot stores changes made to files and I have a 10 GB database where someone removed let's say 400 MB of data and then added 500 MB of false data. The original 10 GB database remains untouched, only these 500 MB of new data are in the snapshot. Restoring the entire original file works by mounting the snapshot share, selecting the day before the desaster, and then restoring the entire file.

I must be wrong, I'm describing deduplication here I guess. Is there a detailed description on how snapshots work?

6. Initiator software for MacOS X. I played around with the free OpenSAN iSCSI initiator for OS X but it seems to lock up from time to time. Whenever I don't access the target for about 10 minutes I can't access it anymore - I get a lock up when I try to copy something on/off the volume. Is the ATTO initiator any better? So far I've only found these two. Of course there will be no original Apple Inc. iSCSI initiator so they can have customers stick to their expensive, yet reliable Xraid technology via FC.



I'd appreciate it very much if you could take the time to help me out with answers! Thanks!!

-- Lars