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Best Redundant Storage for Home Use?
Brad Mace asks: "Despite my hard drive's dedicated service, I'm aware that it will someday fail. I'm not really interested in burning 100 CD-Rs to backup my hard drive, so I've been looking at RAID solutions. Obviously I don't need the best or the fastest stuff out there. What would be a reasonable setup for personal use? Have people had better experiences with internal raid arrays, external raid towers, or networked storage such as Snap servers? I'm primarily interested in low price and ease of use."
If you buy a RAID card with on board cache make sure the cache is battery backed up otherwise a power cut may corrupt your array. Some of the cheaper cards don't have battery backup.
I run a 6x120Gb software raid here. The redundency is nice but when you get that much storage in one place you start having other concerns.
Drive failures are scary. Note, if you're going with a hardware highpoint 1540 controller: forget raid 5. The array takes forever to rebuild (like 4 days) and sometimes fails midway though causing total data loss. (Other people may have different luck though, my friend is doing hardware on 4x160Gb and not enjoying it). I've had 2 drives fail on my software raid and the rebuild went well enough. I suspect the failures were due to inadequate power from the UPS causing a "brownout" condition when my power went off, since both failures happened after a power outage.
So other problems: thats 600Gb of disk space. Nobody in their right mind wants to sit through an fsck, so a journalling filesystem is needed.
but, all the journalling filesystems are new and untested. New your saying? They're a few years old.. and yes, thats true but they're new in comparision to all the other filesystems. And when you're talking about 600Mb of data on one filesystem it really starts to concern you.
(Even so, I've been running raid 5 with journalling on 4 to 6 drives for the last 1.5 years or so and haven't had filesystem corruption)
A friend of mine is running mixed drive sizes in his fileservr and doing no raid. He occasionally has failures and loses stuff, but at least he doesn't lose everything. Still, I'd be pissed if I lost an 80 gig chunk at a time.
The problem with raid is, you gain some redundency but you completely lose the ability to make sensable backups. Unless you're a corporation and can afford $3k for a tape drive (and an additional $500 for tapes) you're faced with the idea of mostly redundent, but no backups. Offsite backups become really appealing, but then you need to shell out the same money for drives that won't be put to use (until something happens)
I still don't have a solution for offsite backups.
As an aside, I started playing with encrypted partitions (not raided). That has the same sort of scaryness. One filesystem screwup and you lose everything. No backups unless you have a second hard drive. Then you're faced with raid 1 which would corrupt both drives, or copying the encrypted volume from drive to drive each night.
I've got no answer for that one ethier, except that encrypting a tape backup would probably be good in a corporate situation.
OK, my own experiences in this area:
I was looking for a basic, cheap RAID system to give me some redundancy.
I got an Adaptec 1200A RAID Controller card, and used two drives in RAID1 mode. This served me well, until I needed more capacity - RAID1 has 100% wasted space.
So I looked at RAID5. I got a Highpoint RocketRAID 454, because it was cheap. BIG mistake. The write performance, on my P4 2.8 Ghz, with three WD1200JB drives, was a terrible 9 Mb/sec, with 80-100% CPU usage. AVOID. I returned it then next day.
Now I have a Promise SuperTRAK SX6000. It's very nice, 25 Mb/s write with only 20% CPU thanks to RISC processor, but expensive.
In summary:
If you want RAID1 only, a nice cheap Adaptec will do fine. If you want RAID5, you will need a reasonable card. Promise do some cheaper ones than the SX6000, with less channels, you could look at those.
Hope this helps!
I've been dealing with mirrored RAID cheap harddrives for a couple of years now on medium duty systems (in harsh environments), and I can tell you two things:
1) I haven't yet seen a situation where both hard drives failed simultaneously so badly that I couldn't recover most* of the data.
2) RAID is not a replacement for a good backup.
No matter what, you should keep a seperate copy of the data at minimum separate from the computer itself, ideally offsite. You should also have a mirrored setup so a small failure (one drive, or fried computer with still working drive) won't set you back to your previous backup data.
What I've done temporarily is use a HD caddy (but now I'd go with a USB 2.0 or Firewire drive) to take an occasional snapshot which I can take offsite, storing it in a different place.
You should plan on expending at least $200 for a decent backup solution.
Further, I suspect you overestimate your backup needs. Compression helps with most everything. If you are backing up movies, burn them to DVD and keep them offsite. If you are backing up programs, burn those to disc and keep them offsite. If you are backing up pictures, burn them the DVD and keep them off site. You only need to continually re-backup items that change over time, and that data is vastly smaller than what you think you need to back up right now, and generally can be compressed up the wazzoo.
But you're looking for the easy way out. So, do mirrored drives, and try to get an external drive at some point later in time.
-Adam
*I did have lightening take out a server, which fried everything in that computer. I'm glad I had a regular backup. For kicks, I tried anyway, and one hard drives still worked, but a small portion of the data was corrupt, and it wasn't worth fixing since I had a known good backup from the night before.
Software RAID
You are just looking to ensure that if one HDD goes down, you still have most of your data. Software RAID mirroring incurs large performance penalties. Oh, and do note that many companies produce "Hardware RAID" cards that aren't hardware raid. Its hardware ASSISTED raid. These systems can't, or have great dificulty booting root of a raid system.
Hardware RAID
Either SCSI or IDE. I've changed my tune about IDE RAID. If you do it in hardware, it is a pretty good and valid option. It provides increase in speed and ease of setup (in most cases, litteraly plug and play). 3ware are a good company for hardware IDE raid controllers. Also they are very well priced.
Big hunking hotswappable SCSI RAID
If you have money to blow, here's the best place to blow it. Here the RAID system (whatever level) is done with hotswapping drives. 99.99% of the time, THIS IS A WASTE OF MONEY. For most small companies, and a lot of midrange companies, hotswap is throwing money away. Unless your server NEEDS to run 24/7 with 5 nines reliablity, hotswap is a waste. Hotswap only offers the ability to replace a bad drive without downing the system. But if you want to spend the money, or like the look of the flashing lights on the cases, go for it.
Ok, next, is RAID the answer?
Yes and no. RAID (mirroring) protects against hardware failure. It doesn't stop anyone from typing `rm -rf /` or anything similar. So if you want backups against mistake, RAID doesn't offer this.
Backups
Unless you have money to burn, tape backups are expensive. Most of us have 20 or 40 gig HDD drives. If you try and buy a tape backup at this level, you are talking a significant ammount of money (eg possibily the same as the cost of your system in the first place).
It is possible to do tape on the cheap, but not recommended.
CD/DVD burners
CDs hold 700MB of data (maximum), so doing a 20gb backup would require 29 CDs in total. This is probably not viable. So lets put that asside for now.
DVDs hold between 2 and 4GB (depending on various hardware, etc). That becomes more viable. You wouldn't do a full backup each day with this mehtod (still requiring 6 dvds to do 1 full backup), but you can do it using a base + data method.
By backing up the entire system on 6-7 dvds say once a month, you can then procede to do incremental backups over the month on 1 or 2 dvds (depending on how much you change). If you also are careful how you store your data, things that you want, but aren't likely to change. Eg your mp3 collection, you can backup to a seperate dvd, saving space on your incremental and full system backup.
Removable HDDs
The final option is, imho, the best. By having, preferably, 2 external HDDs (either using USB drive holders or the old caddy system), you can backup most, if not all of your system onto the removable drive. If you get removable disks that are the same size as your internal HDD, you can backup the entire system.
The pros are obvious. The cons however may bite you. First, in theory, you can drop a tape on the ground and have no problems. Do NOT drop your remoable HDD. So you'll need to be careful. HDDs are also rather more volatile than tapes or CDs when it comes to keeping its data. You'll need to ensure that you store the HDDs in a good location.
If one HDD fails (either a removable, or your internal) you'll be able to restore from one of the working ones. I said you should have atleast 2 removable HDDs because when you do a backup, the first thing you do is delete the old data from the removable. if the system failed then, you are screwed.
I prefer this system, and for some SOHOs I offer it as a viable option if they need data backups.
Summary
Either way, in the end, it comes down to how much you are willing to pay. Backups are still NOT cheap. Its something that should change, but in the short/medium term, it won't.
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