One for IT guys
 

I was going to ask this in one of IT forums I am member off, but they have issue that I cannot login at the moment so here it goes:

I have currently setup Dell Poweredge 2950 server with 2x quad Xeon processors running 3x2TB in Raid 5 +1x 2TB hot spare but this is overkill for my needs and I am downsizing to HP Microserver Gen8 to reduce power costs. Currently it costs me £250-300 in electricity per year and I am expecting it to be £30-50 per year on HP Microserver. While I do like RAID 5 unfortunately HP Microservers do not support it so my choices are 0, 1, 1+0 or 0+1. I know that if I was using 4 disks it would be best to use 1+0 instead of 0+1 for reliability but I am using 1 bay for OS drive so only have 3 available. My idea is to use 2 of old 2TB drives in RAID 0 and sell the other 2, get another 4TB drive and do RAID 1 between single 4TB drive and 2x2TB Raid 0 array. Important data is backed up on another external drive anyway and very important backed up in several places including cloud.

Does it sound like a sensible idea or not.

PS if anybody would be interested in Dell Poweregde 2950 with 2x E5450 Quad core Xeon processors, 16GB of RAM, Perc 6i Raid card let me know as it will be available after I complete migration.

Might depend what software you're running on the hp microserver. Mine's running x4 3 TB WD reds plus a small HDD with the os (openmediavault) and is running RAID5 (about 8TB total)

If you get a cheap 5.25 to 3.5" drive caddy you can use the optical slot in the top for the os drive

I've just setup a Microserver Gen8 at home, from what I can work out from my smart meter its consuming about 85watts of power running 4 HDDs, a single SSD in the ODD bay and upgraded to 16GB Ram.

I've gone down the VM route and running ESXi6 free version which is booting from a USB Stick plugged into the internal USB port. It also has an internal MicroSD slot which can boot ESXi.

I've got 4 drives, 2 WD Red NAS 2TB drives stripped only and 2 Seagate drives also stripped only. I have a good backup routine of off and onsite backups to backup my 900GB of data using USB3 drives for speed.

This is a good source of info on the GEN8
http://homeservershow.com/forums/ind...m/88-ms-gen-8/

Well, firstly I wouldn't bother with RAID 5 even if it was an option. RAID 5 pretty much became useless several years ago once drive capacities began exceeding 2TB:
http://www.zdnet.com/article/why-rai...rking-in-2009/

For my business customers, where possible I always choose RAID 10 or RAID 1, especially for mission-critical servers. The reason for using mirrored RAID arrays of course is to provide fault tolerance. In other words, it's a convenience thing, rather than a 'backup', to reduce down-time in the event of a drive failure.

So, it depends on how mission-critical your system is. If reducing down-time was an important factor, I'd use a pair of drives in RAID 1 and perhaps keep the remaining bay as a hot swap, backup drive or just extra storage for less important files. If, on the other hand, down-time was less important than storage capacity, I'd probably use 3 drives in RAID 0. As long as everything is backed up, a failed drive just means the server is going to be down for a while until you've replaced it and recovered from backups.

Also, how are you calculating the power consumption comparisons? I would be surprised if the difference is that great.


How much would you be looking to sell the Poweredge for? And does it come with dual PSUs and rack rails?

And people say i'm a geek :rolleyes:

Keep it up though, I love it and always like new ideas.

Marcin gave me plenty today about home security.

For my home file server I run a ZFS pool. Back up is made using Rsync to a separate pool in the same server; and Rsync to a remote server; and a portable HD. 4 copies of all files and all nice and simple +++

clearly i need to come bavl and read this when im sobber, i know my nax is raid 5. so the big wuestion is what should i be doinf ?

Surely the type of RAID you chose depends on what you want to achieve, e.g. performance, redundancy, fast-fix, rapid recovery etc.
Some while since I bothered with this, but the servers I last was "responsible" for were all at least RAID 5 with hot-swap drives, mainly Dell kit.
So if anything failed you just yanked it out and plugged a replacement in while still running. The array was then rebuilt automatically at a hardware/firmware level.

IIRC there was another variant (can't recall which) that was secure against a 2-drive failure. We used that on really critical stuff. My excuse is that I was an IT manager/director not a techie!

I can see the point Mark is making - if the typical read error rate of a large capacity drive is inevitably higher than the error rate that a RAID array can cope with rebuilding from, you're doomed to fail....

Mine's basically a media server for TV/music/films that happens to maintain backups of my desktop and laptop, so there's nothing critical on there. I guess RAID 5 with a load more discs reduces the chances of a failed drive causing a failed rebuild as the missing data may be on another drive?

Just replaced the desktop HDD with a 4TB WD Black due to running short of space! Elsawin takes up a shed load....

At some point I really should sort out a cloud based/off site backup option, given a house fire would lose us everything digital!

Sai Wut? :D


Well, as long as you have backups, I wouldn't worry about it too much. Essentially, the problem with RAID 5 is that, by the nature of how it works, the amount of data that has to be written to rebuild an array of large capacity drives (>2TB) after a replacing a failed drive, exceeds that of the theoretical failure rate of most mechanical drives. Therefore, the chances of further data write failures during rebuild becomes likely.

In enterprise environments, most systems administrators have known about the dangers of RAID 5 for years so it's relatively uncommon. For residential use, RAID 5 is still surprisingly popular, but then having a server/NAS fail in a home-setup will probably be nothing more than inconvenient.

You do have to remember that RAID data mirroring is a convenience thing. Some people confuse the data mirroring aspect of it with backing up, which of course it's not. Everything is mirrored between drives, including corruptions and all deletions (be it intentional or malicious).

RAID 1/10 is generally considered 'best practice' amongst most IT professionals who work with medium to large businesses. For my server setups, I generally have a pair of SSDs in RAID 1 for the Operating System and RAID 10 for both the internal storage and NAS/SAN external storage and backup devices. Rarely do the severs or storage devices I install have any less than 4 bays though.

If you have less than 4 bays available, and you need the convenience of being able to swap-out a failed drive with little-to-no down-time, I'd recommend RAID 1. If you don't need that convenience, RAID 5 is fine, though bear in mind that it (theoretically at least) provides little more fault tolerance than RAID 0.

Precisely.