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exu · Jan 13, 2004, 12:28 PM

Want to know if this scenario is possible or even worth while. Will I get any performance boost with the following configuration.

1 Power Mac G5
2 Fiber Channel Cards Installed
hooked to
2 Xserve RAIDS

will be striped to be one big redundant volume.

Level 3 or 5

I want to know what kind throughput this set up would perform at.

thanks

djohnson · Jan 13, 2004, 03:01 PM

What in the world would you need that mush storage for? Also, I dont think you can turn 2 xserve raids into 1. You can make them 2 huge drives, but not 1. The throughput on this would be very nice though.

burkey · Jan 14, 2004, 01:08 AM

That is exactly what I run right now. My whole system is installed on the Xserve RAID and it is FAST. My Xbench results were something like 250 or 260. I am using the internal discs just for backup purposes.

I have two raid 5 arrays on the Xserve RAID, one on each controller. Then from within OSX, you just create a raid 0 array with the two discs from the array. This is commonly known as a raid 50 array and will, in fact, show up as one disc.

I am a professional photographer and use all that space for digital photographs.

The Xserve RAID is one hell of a machine, though. Highly recommended.

Chad
www.chadburkey.com

djohnson · Jan 14, 2004, 02:20 AM

Wow. That is a lot of space though. How much are you using?

burkey · Jan 14, 2004, 12:24 PM

I only have 6 drives in it (three per controller). The total capacity is 690.21 GB with 322.88 GB available, so I'm using 367.32 GB.

Chad
www.chadburkey.com

3R1C · Jan 15, 2004, 12:51 PM

I heard in the last keynate that the new xRaids allow you to add volumes without having to repartion the whole thing. How the heck is this possible? Do any other Raids do this? This seems like a really big deal to me.

geekwagon · Jan 15, 2004, 01:37 PM

Originally posted by 3R1C:
I heard in the last keynate that the new xRaids allow you to add volumes without having to repartion the whole thing. How the heck is this possible? Do any other Raids do this? This seems like a really big deal to me.

There are lots of systems that can do this, you can even grow and shrink filesystems while programs are still using the disks if you are running the right software/filesystem (such as Veritas Foundation Suite.) As far as I know there is no way to do this in OS X though as there is no software support for it in the OS and Veritas doesn't have an OS X version yet.

I'm sure you could add disks and create a new volume set and format it without taking the old volumes down, though. That is pretty typical of a hardware RAID box.

dfiler · Jan 15, 2004, 01:37 PM

Originally posted by 3R1C:
I heard in the last keynate that the new xRaids allow you to add volumes without having to repartion the whole thing. How the heck is this possible? Do any other Raids do this? This seems like a really big deal to me.

It's always been possible to repartition drives without loosing data. However, the software which pulls such a trick needs to be absolutely bullet-proof. For this reason, large software houses like MS and Apple have been wary of the potential bad publicity. Instead, this has until recently been the domain of third party or open source utilities. It simply appears as if Apple now has their own version of 'Partition Magic'.

CatOne · Jan 16, 2004, 01:18 PM

Originally posted by exu:
Want to know if this scenario is possible or even worth while. Will I get any performance boost with the following configuration.

1 Power Mac G5
2 Fiber Channel Cards Installed
hooked to
2 Xserve RAIDS

will be striped to be one big redundant volume.

Level 3 or 5

I want to know what kind throughput this set up would perform at.

thanks

Ummm... so you're going to stripe together 28 drives?

w00t.

You'll probably be limited by the PCI bus (the FC cards are PCI, not PCI-X). Speeds of over 400 megabytes/sec (sustained) would probably be possible though.

Note, it's going to be lightning fast for large file transfers. A big RAID 50 stripe like that won't be super fast for lots of small file transfers. What you're building is a bullet train that can go 700 mph. It'll still be out-accelerated by a go-kart (i.e. a 15K SCSI drive ;-)

CatOne · Jan 16, 2004, 01:20 PM

Originally posted by burkey:
I only have 6 drives in it (three per controller). The total capacity is 690.21 GB with 322.88 GB available, so I'm using 367.32 GB.

Chad
www.chadburkey.com

If you have 6 drives, it makes a helluva lot more sense to put all of 'em on a single side of the Xserve RAID than to put them on either side and stripe them.

Using two controllers, you're twice as likely to have the volume go offline if a RAID controller fails, and you're a lot less efficient with the space.

I'd say get 7 drives, and put them all in one side. Create a 6 drive set and use the 7th as a hot spare, so you can have two drives fail without losing data. It won't come close to saturating the fibre link (2 gbit/sec) so the dual channel throughput won't help ya.

geekwagon · Jan 16, 2004, 01:50 PM

Originally posted by CatOne:
Using two controllers, you're twice as likely to have the volume go offline if a RAID controller fails, and you're a lot less efficient with the space.

This is my biggest beef with the XServe RAID and I really hoped they would solve this in this rev (but looking through the specs it doesn't look like they did.)

Pretty much all of my other storage boxes (Compaq, EMC, etc) have redundant array controllers where each can see all the drives in the whole enclosure. With an XServe RAID the only way to get true redundancy is to stripe each side and then mirror the sides.

Maybe they don't do this because there is no software like Volume Manger that will manage OS X being able to see the same physical disk as two different addresses for OS X? Seems shortsighted to limit something in hardware that could eventually be solved with software, though.

CatOne · Jan 17, 2004, 06:44 PM

Originally posted by geekwagon:
This is my biggest beef with the XServe RAID and I really hoped they would solve this in this rev (but looking through the specs it doesn't look like they did.)

Pretty much all of my other storage boxes (Compaq, EMC, etc) have redundant array controllers where each can see all the drives in the whole enclosure. With an XServe RAID the only way to get true redundancy is to stripe each side and then mirror the sides.

Maybe they don't do this because there is no software like Volume Manger that will manage OS X being able to see the same physical disk as two different addresses for OS X? Seems shortsighted to limit something in hardware that could eventually be solved with software, though.

Well, it's the first version of Xserve RAID. We can hope that a future version includes it, I'm sure you're not the first to ask Apple for it

djohnson · Jan 17, 2004, 07:09 PM

I thought of something that has bugged me when they updated them. Why didnt they add serial ata? Seemes like it would have sped some things up...

CIA · Jan 17, 2004, 07:14 PM

I don't think even those 10K Raptor drives saturate a PATA bus. Maybe in rare burst mode, but...
Plug in/Hot swap drives work the same way in for PATA and SATA, no cables.
On that note, are those drives "locked" in? Or can anyone just walk by and start pulling drives. (sabatoge?)

djohnson · Jan 17, 2004, 08:06 PM

They have 10K Raptor drives? Awesome, didnt know that...

CIA · Jan 17, 2004, 08:36 PM

10K (10,000RPM) SATA Drives.

I take my old statement back, looks like they are only avail in SATA....

TMLai · Jan 19, 2004, 01:28 AM

---------------------------------
That is exactly what I run right now. My whole system is installed on the Xserve RAID and it is FAST. My Xbench results were something like 250 or 260. I am using the internal discs just for backup purposes.

I have two raid 5 arrays on the Xserve RAID, one on each controller. Then from within OSX, you just create a raid 0 array with the two discs from the array. This is commonly known as a raid 50 array and will, in fact, show up as one disc.
---------------------------------

Hi burkey,

how do you boot from your raid 50. Please shared details. Thank you.

burkey · Jan 19, 2004, 02:45 AM

Originally posted by TMLai:
---------------------------------
That is exactly what I run right now. My whole system is installed on the Xserve RAID and it is FAST. My Xbench results were something like 250 or 260. I am using the internal discs just for backup purposes.

I have two raid 5 arrays on the Xserve RAID, one on each controller. Then from within OSX, you just create a raid 0 array with the two discs from the array. This is commonly known as a raid 50 array and will, in fact, show up as one disc.
---------------------------------

Hi burkey,

how do you boot from your raid 50. Please shared details. Thank you.

Well, it is actually pretty straightforward. First I built the two raid 5 arrays on the xserve raid. Then I made a disc image of my old system using Carbon Copy Cloner. Then I booted from a Panther installation disc. When the first screen comes up there is an option in File menu (I think) to run the Disk Utility, where I created the stripe array from the two array discs and restored the previously created system image.

Here is the tricky part: One has to either hold down the option key at every reboot and select the array as the boot device or make the internal drive(s) unbootable. This is apparently because of the extra time that the fibre channel/xserve raid need to initialize.

Chad
www.chadburkey.com