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Is ZFS and RAID-Z worth using in home made NAS (freeNAS for example)

Features of ZFS and RAID-Z look vary promising. Looks like it is a perfect FS for home NAS solutions, poor man's Drobo things and alike.

Are there any drawbacks I should be aware of?

Running two DHCP Servers in the same network

I have connected my raspberry pi with a wireless access point and would like to run a DHCP Server on the RPi to assign the IP and gateway correctly. This is because the RPi serves as a gateway to a VPN. Unfortunately, the access point also runs a DHCP Server which I can't deactivate for some reason. What is the best way to automatically get the correct settings from the RPi spread to all wifi users?

Server vs. Desktop

I'm looking to build a set of home servers to play around with. In doing so they will be on full time, looking to run a very low volume family web site, and probably a file server with SFTP etc on it as a separate device.

My question amounts to, given that configuration, what would make server hardware worth the extra cost as compared to buying desktop hardware and running the same open source server software?

What is it about server hardware that makes it better?

Is it possible to run a laptop which can't display anything?

I have a laptop with a busted up graphics card. However I'm pretty sure that the rest of it works just fine. I was wondering if it was possible to use it as a home server and how I would do that given that I'm not able to see anything.

Did I just fail at hot plugging a drive?

I have a small home server built around a Lian Li PC-Q25 case with a SATA backplate advertising itself as hot pluggable. The motherboard is Asus P8H77-I. I have 4 SATA drives attached to the backplate - two pairs built into RAID1 arrays. The system is running on Centos 6.3 x86_64.

One of the drives broke down, so I did the recommended procedure: synced, removed it from the array, shut it down properly and pulled it out. No disaster here, I could hear the drive spin down and no errors appeared in the dmesg log.

Now, I assumed that by the SATA standard the staggered pins in the drive would ensure a safe plug-in without any sudden power surge. Pushing the drive in, I could head the other drives slow down and click their heads for a very brief moment.

Checking the dmesg log revealed the following:

ata1: exception Emask 0x10 SAct 0x0 SErr 0x4090000 action 0xe frozen
ata3.00: exception Emask 0x10 SAct 0x3ff007ff SErr 0x4890000 action 0xe frozen
ata3.00: irq_stat 0x08400040, interface fatal error, connection status changed
ata3: SError: { PHYRdyChg 10B8B LinkSeq DevExch }
ata3.00: failed command: WRITE FPDMA QUEUED
ata3.00: cmd 61/80:00:3f:81:ca/00:00:00:00:00/40 tag 0 ncq 65536 out
         res 40/00:54:bf:81:ca/00:00:00:00:00/40 Emask 0x10 (ATA bus error)
ata3.00: status: { DRDY }

(The last ata3.00 messages are repeated about 20 times with different numbers but the same text)

The last lines are:

ata3.00: status: { DRDY }
ata3: hard resetting link
ata2: exception Emask 0x50 SAct 0x0 SErr 0x4090800 action 0xe frozen
ata2: irq_stat 0x00400040, connection status changed
ata2: SError: { HostInt PHYRdyChg 10B8B DevExch }
ata2: hard resetting link
ata1: irq_stat 0x00400040, connection status changed
ata1: SError: { PHYRdyChg 10B8B DevExch }
ata1: hard resetting link
ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
ata1.00: configured for UDMA/133
ata1: EH complete
ata2: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata2.00: configured for UDMA/133
ata2: EH complete
ata3.00: configured for UDMA/133
ata3: EH complete

Also my logwatch reported the following changes in SMART data:

/dev/disk/by-path/pci-0000:00:1f.2-scsi-2:0:0:0 [SAT] :
    Prefailure: Raw_Read_Error_Rate (1) changed to
          100,
    Prefailure: Reallocated_Sector_Ct (5) changed to
      200,
    Prefailure: Spin_Up_Time (3) changed to
      100,
    Usage: Seek_Error_Rate (7) changed to
      200,

 /dev/disk/by-path/pci-0000:00:1f.2-scsi-3:0:0:0 [SAT] :
    Usage: Calibration_Retry_Count (11) changed to
      100,
    Usage: Load_Retry_Count (223) changed to
      100,

Device: /dev/disk/by-path/pci-0000:00:1f.2-scsi-2:0:0:0 [SAT], Self-Test Log error count increased from 0 to 1

On the following day the SMART log still had suspicious entries in it:

 /dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 [SAT] :
    Usage: Seek_Error_Rate (7) changed to
      200,

 /dev/disk/by-path/pci-0000:00:1f.2-scsi-1:0:0:0 [SAT] :
    Usage: Seek_Error_Rate (7) changed to
      200,

 /dev/disk/by-path/pci-0000:00:1f.2-scsi-2:0:0:0 [SAT] :
    Usage: Multi_Zone_Error_Rate (200) changed to
      200,

 /dev/disk/by-path/pci-0000:00:1f.2-scsi-3:0:0:0 [SAT] :
    Usage: Throughput_Performance (2) changed to
      56,

 /dev/disk/by-path/pci-0000:00:1f.2-scsi-4:0:0:0 [SAT] :
    Prefailure: Raw_Read_Error_Rate (1) changed to
      116, 117,
    Usage: ECC_Uncorr_Error_Count (195) changed to
      116, 117,

So, apparently the sata backend just brutely powered the drive on immediately, possibly causing the voltage to drop for a moment.

My mistake was perhaps to plug all four drives in the same PSU rail and expect the PSU (albeit a 800W Seasonic with good specifications) to cope with the sudden power draw.

The SATA backplate has two Molex connectors on the back for power - I'll plug them to separate PSU rails to ensure a steadier power output.

Is there a way to prevent the drive from spinning up immediately as I stick it back into the drive pack?

Also, did I possibly just damage the drives (can it be seen from these log messages)?

Thank you!

How to Set Up a First Home Linux Server?

This is the first time I am setting up servers so I'm unsure where to start. One thing I know is that I have chosen the Linux Operating System.

I want to host my own sites so I have a static IP for my dedicated server. What are the issues I need to consider regarding setting up a server at home? Presently, power and security are low priority but you could comment on them.

I am inexperienced and would be glad to know the A to Z of setting up servers.

How do I SCP from remote machine to local machine when I am outside of my home network?

While I understand how to scp files to and from my server from within my home network, how can I scp a file from my server to my local machine when I am on the outside, say at Starbucks?

While I am able to scp from my local machine to my server in this scenario, I haven't figured out how to grab a file from home, using the command line. Any suggestions?

How can I make mdadm auto-assemble RAID after each boot?

I successfully created a RAID (mirroring) by utilizing mdadm. However, I must run the following commands after each boot:

mdadm --stop --scan // to stop /dev/md127 - I don't know where the number 127 even comes from
mdadm --assemble --scan // to start /dev/md0

What am I doing wrong/why do I need to run these commands at boot? What is the right way to auto-start RAID with each (re)boot?

Detecting when a server is running on UPS battery

I have a home server (HP Proliant ML310 G4) that I bought from my employer a month or so ago. The server runs Debian Linux and I use it for just about everything. I can get away with doing this because my needs aren't that demanding so the server is rarely under heavy loads at any given time. This server has a 2 TB RAID1 array (with one hot spare) managed by mdadm that I use for file sharing over my network via Samba. I'm running the OS off a smaller hard drive that is not part of the array.

I have the server powered through a small 255-watt UPS because I need it to withstand minor power fluctuations without coming down. This is very important because a sudden unclean shutdown (caused by a power drop or blackout) can screw up the RAID array, which has already happened on one occasion.

In the event of a power failure, I'm estimating the UPS has only 10-15 minutes of power in it. There may be more but I don't want to automatically assume there is. This is enough to get through blackouts that last a few minutes or less. However, if the power is down for several hours I need the server to properly shut itself down automatically before the UPS power fails. This will hopefully keep the RAID integrity from getting hosed in those situations.

This sort of thing is easy on a laptop b/c it has built-in sensors to determine when it is running on battery power, but this server does not (as far as I know). I have an unusual network setup where my DSL modem is separate from my router. The router is also on the UPS, which allows me to SSH in through my laptop and shut down the server in the event of a power failure. Unfortunately, this only works if I'm there at the time to do it. I need a solution that always works whether I'm there to intervene or not.

Since my DSL modem is not on the UPS, it would go down with everything else if the power fails. I set it up like that deliberately because I have an idea about how to solve this problem: I was thinking of writing a script that would ping google.com or some other high-traffic/high availability site. If the ping completes successfully, the server would keep running. If the ping fails (because the modem is off), the script would think the power is off and would tell the server to shut down. I would add the script to Cron and have it run every 5 minutes. That would hopefully give the server enough time to shut down before the UPS runs out of power.

Before I go to the trouble of writing the script, I would like to know if there is a better way to do what I need. Thanks in advance for any help.

How much will it cost me to run a Windows Home Server?

Anybody has any measurements of how much electricity does a Windows Home Server (say one of the HP models) use while being on 24/7?

I have an old PC running at home to store files that everyone can access from their laptops, but it is using too much power. I'm wondering if it would be worth to buy a WHS to replace it.

Kwh consumption per day or month is what i'm looking for, as rates vary from place to place.

Edit: Here are my conclusions, feel free to let me know if I'm not right.

Based on Stephen measurements (which validate Joel's estimates), I've come to this conclusions:

An HP WHS with a 2Ghz Celeron (rated for 65W TDP) with only 2 HDD and 1 GB of ram could be well under 2 Kwh a day (The 2.4Ghz Quad Cored max TDP is 105W and was measured at 2.5 kwh per day with 4 HDD and 8GB Ram).

That's a saving of almost 3kwh per day against the old box that averaged 4.6 kwh per day (over 1000 kwh per year). @25 cents/kwh we pay here, that's about $275 a year savings in energy, meaning ROI is less than two years at current (likely to go up) electricity rates.

Now, there is also a new HP WHS with a 1.6 GHz Atom processor. I'll have to check its performance since that would mean even greater savings.

Edit 2: The Atom powered WHS (I researched one from HP and one from Acer) claim that load power usage is 26 watts and that they can go to sleep @ 3W and turn back on upon accessed automatically. @ 26w that means 0.6 kwh per day (meaning even faster at less than 1 year ROI).

Edit 3 (Jul 28): Got my hands on a Fluke meter with data logging capabilities and a clamp and took some samples over time of the power usage of my current PC. The average was 3.45 Kwh per day.

What is the advantage of iSCSI over SMB?

At my house I'm running a Hyper-V server with a Windows Server 2008 R2 VM acting as a file server. Files are shared across my network using SMB. (Also, the machine is using a PERC 6/i RAID card but I don't think that's important)

I'm thinking about setting up a dedicated SAN (iSCSI) machine and then switching my Hyper-V server to ESXi.

What are the advantages of using iSCSI versus SMB?

I think I would still need a file server OS (eg. Win 2k8) sharing files via SMB so I'm not sure the end result would be any different than my current setup...

Will the maximum speed of a network card reduce the impact of an incoming DDoS attack?

I’m wondering if the maximum speed of a network card would reduce the chances of a DDoS affecting a home-hosted website.

In this scenario, I’m hosting my website from an Android Tablet where the maximum speed incoming/outgoing is 10mbps.

Best way to organize lots and lots of media files?

I have lots and lots of media files. About 6TB spanned across 10 physical hard drives on a personal file server. Security is not a major issue, but is being handled via other means.

These files consist of video, audio, documents, and software/installers/ISOs/etc.

By the purest of coincidences, this home server is running a legit copy of Windows Server 2008 Enterprise Edition, also running a webserver, sharepoint, TFS, etc etc. So Windows Home Server is not an option. I want to avoid virtualization due to the critical nature of the files in question. Media Center has a horrible interface, and the systems I play from have full-sized keyboards.

What is the best way to manage and organize these tens of thousands of folders and millions of files?

I would prefer some sort of automated system which also manages the filesystem and is aware of files being modified, moved, and added via external means. The ideal solution might have features like media streaming, thumbnails, etc etc.

Is there anything like Microsoft Sync for the home or media center computer?

I just returned from a business trip where my rental car (A free upgrade to a Lincoln MKZ!) had the Microsoft Sync system built into it. You know, from the commercial: 'Play artist, Right On Dynamite' ... [machine voice] 'Playingartistrightondynamite'.

I had my doubts, but I must say, after using it for three days and having the ability to do full control of music, phone, and other sound all from my phone...it's awesome. Plus the ability to call people just by talking. I realize that would be harder to do, since you'd need to mic the entire area you might be in, but I could live with having to be in range of a microphone connected to a PC.

You do need to have a phone with Bluetooth audio capability, which I'm fortunate to have, but I was thinking this would be just amazing at home...you could just keep your phone in a pocket or on your desk and it's like the ultimate stereo remote.

So...how would I set this up at home? I have a couple Macs at home with bluetooth on them, and I have a couple PCs of 2-3 year old vintage that are available. I know Bluetooth to USB dongles are cheap. I'm not really a programmer, but I can hang drivers together. Is it a pipe dream, or could I set this up? Anyone got anything like this working now?

Using my old PC as a web/file server?

I have an old desktop computer that I've been trying to sell for AGES. I guess nobody is looking for computers because it was advertised at a dirt cheap price on craigslist, local papers, etc. Anyways, I was wondering if it would be worth it to set it up as a home file server, a web dev server (I have a web host for actual production use), and maybe host a few server applications (ex: ventrillo). The computer is actually an old Dell that I cannibalized after the motherboard being destroyed by lightning, so it has fairly new parts in it.

The specs are:

• P4 3.4GHz w/ HT and Artic Cooling Freezer 7
• 3GB DDR2 533 RAM
• 80GB hdd (will upgrade the hard drive if it's even worth using as a
  server)
• basic dvd rom
• 430 Watt Thermaltake PSU (it might be important to note that it is only 60% efficiency)
• ATI Radeon x600 256MB
• Antec 300 case

It's not a really beefy machine, I just can't see giving it away or putting it in the corner to just collect dust. I have Windows Server 2008 R2 Standard and I am confident in my skills in operating most Linux operating systems. I'd also be using it to tinker with when I learn new things in my server admin classes (I'm finishing my 2nd year in college at the moment so I'm still learning)

Also, my house is quite old and the electrical wiring is pretty poor (it MIGHT be up to code, then again, where I live most people don't even know what regulations are or let alone know how to spell it...) Would it be safe to leave it running all day and is it going to run up my electric bill because of the PSU efficiency? I only have 5mbit cable internet, but I won't be running very bandwidth intense services on it so it should be ok.

I should elaborate on why I am concerned about the power. The circuits should be fine, but I'm more concerned about fire hazard. What is the likelihood that the server could cause an electrical fire? Again, thank you all for the feedback!