Some NAS hardware questions

[Harbinger]

This isn't Snapserver-related, but the title of the forum suggests that I can ask a storage/NAS related question so here goes...

My attempts to get a Snapserver 18000 have apparently failed (for now), so I've turned my attention to making my own NAS. I purchased a surplus Intel SE7501WV2 motherboard with two Xeon 3.02 GHz processors, dual gigabit LAN ports, and 12 GB memory capacity (it'll have at least 8GB). It also has SCSI RAID capability (0 or 1). I purchased an Intel SR2300 chassis to put the board into. It allows 6 hot-swappable SCSI drives with the ability to fit a 7th in place of the CD/floppy drive assembly. There's also a non-hot-swap bay for a tape drive, which I've determined can hold an 8th hard drive.

I hacked the SCSI hot-swap backplane by removing the SCSI docking connectors and have glued combined SATA data/power cable assemblies in their places. This will make the backplane nothing but a mounting plate for the connectors and a pass-through for the front panel connectors/switches/lights. I purchased a 3Ware 9550 8-port SATA2 PCI-X card to handle the hard drives, and I plan to run at least 6 drives in the beast. Drives will not be hot-swappable; I simply want ease of drive replacement without case disassembly should a drive go bad. I plan on using Openfiler for software.

Now, here are the questions:

1) The board as I mentioned has two G-bit ethernet ports. If my entire home network uses just one 24-port G-bit switch for all computers with no segmentation, is there any advantage to attaching network cables to both ports?

2) The chassis comes with two hot-swappable power supplies, each with its own power cord. In normal use, would you have two separate power feeds for the box, perhaps on different power segments, to prevent complete power loss? Or are the dual supplies provided simply in case one of the supplies craps out in use?

I plan to post complete construction details on my blog when I'm done, and will list the link for those interested in reading them.

[blue68f100]

1. If your hardware (switch and NAS/Server) supports Link aggergation 802.3ag or tunking it will help on through put if you have more than 1 users/pc. Otherwise no gain unless you want 1 pc direct access to it for max speed/backup.

2. I would connect both. Even though I have yet to ever have a PS die in any of my servers. The second PS is for auto roll over when/if the main one fails. If you by odd chance have 2 separate dedicated power sources use it, but that would require 2 UPS units to maintain too.

[Harbinger]

Good info--thanks for your input!

[Terry Kennedy]

Originally Posted by Harbinger

1) The board as I mentioned has two G-bit ethernet ports. If my entire home network uses just one 24-port G-bit switch for all computers with no segmentation, is there any advantage to attaching network cables to both ports?

Unfortunately, most load balancing is rather primitive and you normally won't see much greater throughput. Balancing tends to work based on source/destination MAC pairs, sometimes just one or the other. So you wind up with most of your traffic on one port or the other, or input on one port and output on another. These graphs show what happens between a FreeBSD NAS (using the lagg interface) and a Cisco Catalayst 4848 port channel:

Port 1:


Port 2:


Port Channel:

2) The chassis comes with two hot-swappable power supplies, each with its own power cord. In normal use, would you have two separate power feeds for the box, perhaps on different power segments, to prevent complete power loss? Or are the dual supplies provided simply in case one of the supplies craps out in use?

It is best to connect both of them. The most common power supply failure seems to come from the fan(s) going bad and overheating the unit. With both powered, you can recover from a supply shutown and replace the failed one at your convenience.

I plan to post complete construction details on my blog when I'm done, and will list the link for those interested in reading them.

Over 6 years ago, I built my first RAIDzilla servers to replace my stack of 12 Snap 4100's.

The second generation RAIDzilla II's have been running for over a year now, and I'll get around to a full write-up eventually. The idea is sort of the exact opposite of the Backblaze Pod - "How much can you spend on a storage device?".

These units each have dual Xeon E5520's, 48GB RAM, 256GB PCIe SSD, 32TB of dedicated ZFS pools, plus redundant 320GB OS drives:





These will do sustained transfer rates of 500MB/sec over a period of 24 hours locally. Obviously, network performance is limited to about 115MB/sec. The 10-second burst rate is over 4GB/sec.

[Harbinger]

Terry--

Ah! You're the RAIDzilla guy! I've read the info on your first build several times, and pointed others to it as well. Good job! I'd love to read about RZ2 when you get the chance to write about it.

Thanks for posting the graphs and comments as well. I thought about installing the OS to an embedded CF card but was told two things: 1) If I do, I should install to two RAIDed CF cards in case of failure, and 2) I should install the OS to the storage RAID for (more) failure-proof operation. I think I've decided to install to the RAID after backing up my configs. If two drives fail I'm toast under RAID 5 anyway, so some redundancy without adding complexity with dual-boot OS drives will be a good thing for me. Mine isn't mission-critical like your setup, anyway...it's just for home media serving.

[Terry Kennedy]

Originally Posted by Harbinger

Ah! You're the RAIDzilla guy! I've read the info on your first build several times, and pointed others to it as well. Good job! I'd love to read about RZ2 when you get the chance to write about it.

Thanks! Yes, I'll definitely post a link to it here.

Thanks for posting the graphs and comments as well. I thought about installing the OS to an embedded CF card but was told two things: 1) If I do, I should install to two RAIDed CF cards in case of failure, and 2) I should install the OS to the storage RAID for (more) failure-proof operation. I think I've decided to install to the RAID after backing up my configs. If two drives fail I'm toast under RAID 5 anyway, so some redundancy without adding complexity with dual-boot OS drives will be a good thing for me.

A lot depends on what OS you're using and how hard it would be to get back to a working config after a loss of the OS files. A pre-packaged NAS-ish OS (FreeNAS, Openfiler, etc.) would probably be a lot easier to reinstall than something like my heavily-customized FreeBSD configuration.

I expect that at least some of the comments about redundant CF cards is due to the number of writes an OS will do to log files. CF cards generally don't have the sophisticated sort of wear-leveling algorithms that you see in newer SSD's.

Going with separate, mirrored, OS drives is one of the things I learned from the original RAIDzilla, which kept its OS (FreeBSD 5.x through 7.x) on the RAID array. As it turns out, moving the OS off the array was a good call for other reasons as well (as I was testing various improvements to the disk drives, the drive manufacturer and I did a bunch of "here's 20 new drives - pull out the old ones and send 'em back" cycles, which would have been a real pain if I'd needed to restore the OS each time).

The RAIDzilla II's were initially loaded with an early beta of FreeBSD 8.0. I had decided to use ZFS for the filesystem (even at 2 TB, a UFS filesystem took forever to check, and I can't imagine what a 32TB one would be like), and FreeBSD didn't get solid bootable ZFS support until post-8.2-RELEASE. So the separate OS drives meant that I could have a fully working system for development, with no ZFS pool at all. Much of my early testing and design validation was done with only 1 or 2 2TB drives in the pool - I didn't want to run out and buy a hundred 2TB enterprise drives and discover I'd made a poor choice. I did end up sticking with the original brand I'd chosen, which have been running solidly since the 1st of the year.

Mine isn't mission-critical like your setup, anyway...it's just for home media serving.

Mine are in my house, too. Though I'm certainly not the average home user. There's also a 48-slot robotic LTO-4 library to back the 'zillas up to tape.