(12:59:57 PM) generalhan: JonathanD: is this sotrage software the same, regardless of the model ?
(1:00:05 PM) JonathanD: generalhan: for the 4000 series, yes.
(1:00:14 PM) JonathanD: this is what you would see.
(1:00:36 PM) generalhan: ok it looks very similar to the DS3400 software doc
(1:00:40 PM) JonathanD: so, what makes a SAN different from a NAS...
(1:00:42 PM) JonathanD: generalhan: it is :)
(1:01:15 PM) JonathanD: a NAS is a network share, basically, like a windows network share. different machines can use it, and store things there. You can use it with normal networking hardware, nothing special.
(1:01:22 PM) Deech: SAN attaches via high speed fiber to a server, whereas a NAS connects via Ethernet? 
(1:01:31 PM) scratchme: Generally.
(1:01:32 PM) JonathanD: A SAN, generally, is seperate, on it's own network, and doesn't have shares.
(1:01:37 PM) JonathanD: It has LUNs
(1:01:52 PM) JonathanD: which are assigned to hosts.
(1:02:06 PM) JonathanD: a LUN is a Logical unit number. to a server, a LUN is a physical disk.
(1:02:17 PM) JonathanD: on a scsi bus, each drive is a LUN.
(1:02:32 PM) generalhan: can any one disk (or array ) be split into multiple LUNs ?
(1:02:58 PM) JonathanD: generalhan: yes. We'll take a look at how that works in a moment.
(1:03:05 PM) generalhan: k
(1:03:25 PM) JonathanD: so, a LUN, presented to a host, is functionally the same as a physical scsi disk installed IN that host.
(1:03:36 PM) JonathanD: thats the single biggest difference between SAN and NAS.
(1:03:57 PM) JonathanD: so, lets take a look at our san here.
(1:04:21 PM) scratchme: JonathanD: Try not to click around without giving at least a sec or two.
(1:04:28 PM) scratchme: We won't be able to follow the screen updates.
(1:04:34 PM) Deech: but the ds4k series doesn't use scsi, it uses SATA?
(1:04:38 PM) JonathanD: this is a demo system. It has 2 drawers, one with 16 SATA drives, one with 10 FC drives.
(1:04:55 PM) JonathanD: Deech: it uses SATA or FC. FC is funtionally equiv to SCSI
(1:05:02 PM) Deech: k
(1:05:02 PM) JonathanD: from a performance perspective
(1:05:15 PM) JonathanD: but all these disks are connected to the 4000 via fiber
(1:05:34 PM) JonathanD: so, you can "see" the disks right now, right?
(1:05:38 PM) generalhan: and to the hosts via .... ?
(1:05:42 PM) JonathanD: generalhan: fiber
(1:05:44 PM) generalhan: k
(1:05:51 PM) JonathanD: on the right, we have luns.
(1:06:07 PM) JonathanD: we're going to look at how you create a LUN and where it comes from
(1:06:25 PM) JonathanD: everyone ready?
(1:06:28 PM) generalhan: oh yeah
(1:06:39 PM) Deech: lets do it
(1:06:43 PM) scratchme: =)
(1:06:54 PM) JonathanD: I have about 600GB of unconfigured Fibre disk space.
(1:06:57 PM) JonathanD: as you can see.
(1:07:07 PM) JonathanD: thats those 7 drives which currently have little purple things under them.
(1:07:43 PM) JonathanD: you can see here the drive selection and raid options.
(1:08:02 PM) JonathanD: we're going to create a 3 disk raid 5, right now.
(1:08:25 PM) JonathanD: which will give us 135GB, after parity.
(1:08:31 PM) scratchme: What's enclosure loss protection ?
(1:08:36 PM) JonathanD: someone let me know if I'm going to fast for updates.
(1:08:41 PM) JonathanD: scratchme: consider the following.
(1:08:49 PM) JonathanD: You have a DS4000 with 8 enclosures.
(1:08:53 PM) JonathanD: (that is, disk cabinets)
(1:09:02 PM) generalhan: like expansion units ?
(1:09:10 PM) JonathanD: you build your arrays, as 8 disk raid 5 arrays, going vertically down the cabinets
(1:09:14 PM) JonathanD: yes, generalhan
(1:09:33 PM) JonathanD: so disk 1 in each is part of array 1, disk 2, array 2, and so on.
(1:09:46 PM) JonathanD: if you lose an entire enclosure, somehow, you still are online.
(1:09:54 PM) scratchme: Interesting.
(1:09:58 PM) JonathanD: as you have lost only one disk from each array.
(1:10:05 PM) JonathanD: that is enclosure loss protection
(1:10:09 PM) generalhan: very interesting
(1:10:21 PM) scratchme: $$$$ bling bling though.
(1:10:25 PM) JonathanD: losing an enclosure is a RARE thing, but if a customer does have enough enclosures to do this, we will do it.
(1:10:26 PM) generalhan: lol
(1:10:34 PM) JonathanD: otherwise, it's considered minor.
(1:10:38 PM) Deech: Ah. so that little notification is telling you if those drives are located on different arrays. 
(1:10:45 PM) Deech: err.
(1:10:47 PM) Deech: enclosures
(1:10:59 PM) JonathanD: Deech: well, it's telling me that TOO many drives from this array are in the same enclosures.
(1:11:08 PM) Deech: ah. I see
(1:11:24 PM) JonathanD: you can do loss protection with only 2 enclosures, too.
(1:11:27 PM) JonathanD: with raid 10
(1:11:47 PM) Deech: makes sense. You'd need three enclosures to do raid 5
(1:11:50 PM) JonathanD: so now,wwe're looking at the next screen. here, we define the lun size and name.
(1:11:54 PM) JonathanD: Deech: correct.
(1:12:05 PM) JonathanD: enclosures failing is pretty unlikely, anyway.
(1:12:26 PM) JonathanD: each has redundant power, and 2 ESMs, which are the devices that connect the drives to the controllers
(1:12:29 PM) scratchme: Okay, so here you are defining logical/virtual disks carved out of the array you just created?
(1:12:35 PM) JonathanD: scratchme: exactly.
(1:12:40 PM) JonathanD: lets make 2
(1:12:49 PM) JonathanD: so, an array can be used by more than one host.
(1:12:56 PM) generalhan: thats perfect
(1:13:04 PM) scratchme: So you could if you wanted, make the whole thing 1 giant RAID 5 + hot spares, and carve luns out for various uses, right?
(1:13:20 PM) JonathanD: scratchme: yes, but that would be a bad idea for more than say, 8 drives.
(1:13:26 PM) scratchme: Why?
(1:13:38 PM) JonathanD: scratchme: raid 5 rebuild time increase rapidly past 8 drives.
(1:13:44 PM) scratchme: Really?
(1:13:56 PM) billfur [n=billfur@atarack/member/billfur] entered the room.
(1:14:01 PM) JonathanD: a rebuild that took 2 hours on 8 disks could take 8 hours on 10
(1:14:02 PM) scratchme: So like a 20 drive RAID 50, or RAID 10 would be okay right?
(1:14:07 PM) generalhan: thats really what i wanted to do was 2 RAID5 arrays and split out 3 LUNs per array to take care of my 6 blades
(1:14:12 PM) JonathanD: scratchme: both would probably be fine.
(1:14:27 PM) Deech: seems it'd be a better idea to create multiple raid 5 arrays and carve them out as needed. 
(1:14:33 PM) JonathanD: so what were looking at now is LUN characteristics
(1:14:45 PM) billfur: do we have a log of what I've missed by chance?