Hard drive advice

[mapes]

So RAID is faster than one drive alone ??

Tell me more folks, how much faster ??

Think about it. If you have a file system that spans two or more hard drives when the OS gos to read from that file system it has two drive heads to read from. In the storage biz (where I work) it's called having more "spindles" (i.e more drives.. not necessarily more drive space). Meaning a 1 TB file system on a raid with 10 drives is way faster than a 1 TB filesystem on a raid with five drives. Because you can support up to twice as many simultaneous reads and writes. Of course this all depends on the type of raid controller and the type of raid.

[mapes]

This is an excellent discription of each type of raid level

http://www.acnc.com/raid.html

[WalkinTarget]

Just a quick note on RAID speeds here ... the only true performance boost using RAID is found when accessing large files (think: the load screen when switching maps in a game) but for small files that are routinely read and then the spindles move on, it is not 'efficiently' faster than a single drive.

You will notice a bigger change by using a faster RPM drive, say from moving to a 10k rpm over a 7,200 rpm unit, rather than a RAID array that for 75% of your PC time is doing nothing more than email/browsing.

Thats why I haven't moved to RAID yet, but I should at least invest in a Raptor for my main rig. And one more RAID note .. if you want speed, you lose redundancy. If you want redundancy, you lose speed, unless you move to 4 drives instead of two.

[mapes]

Just a quick note on RAID speeds here ... the only true performance boost using RAID is found when accessing large files (think: the load screen when switching maps in a game) but for small files that are routinely read and then the spindles move on, it is not 'efficiently' faster than a single drive.

You will notice a bigger change by using a faster RPM drive, say from moving to a 10k rpm over a 7,200 rpm unit, rather than a RAID array that for 75% of your PC time is doing nothing more than email/browsing.

Thats why I haven't moved to RAID yet, but I should at least invest in a Raptor for my main rig. And one more RAID note .. if you want speed, you lose redundancy. If you want redundancy, you lose speed, unless you move to 4 drives instead of two.

I disagree

There is a speed increase no matter what the size of the file...it's just a bigger increase with large files. You can tune this with the block size of the filesystem. If your filesystem allows you to select the block size that is.

Another thing is I think most MB raid implementations use the CPU instead of a dedicated raid controller so theres a performance loss there as well. especially if your doing redundancy. It cost CPU cycles to calculate ECC on the writes.

You can actually get speed and redundancy from a three drive raid 5 array. Three drives is the minimum for raid 5. In raid 5 both the data and the ecc parity is striped across all drives. Actually raid 5 is one of the better performing raid levels

[Duke{CLR}]

I am a RAID noob but I'm going to buy a 3rd Seagate drive to set up a RAID 5 because of what I read. Its good to hear you say those nice things about RAID 5. I plan on benchmarking before and after I set it up so I should be able some data.

[WalkinTarget]

Another thing is I think most MB raid implementations use the CPU instead of a dedicated raid controller

Should have added that to my post ... thanks for the addtnl info, mapes. As always, a clarification/correction is most assuredly welcome. There's hardware RAID and there is HARDWARE RAID.

I should have learned my lesson back in my SCSI days when I bought a $44 SCSI controller and thought it would perform equal to an Adaptec 2940 ... HAHAHAHAAA, what a marOON I was !!!

[mapes]

Should have added that to my post ... thanks for the addtnl info, mapes. As always, a clarification/correction is most assuredly welcome. There's hardware RAID and there is HARDWARE RAID.

whoa a 2940 I havn't seen one in years...wow I remember those

I should have learned my lesson back in my SCSI days when I bought a $44 SCSI controller and thought it would perform equal to an Adaptec 2940 ... HAHAHAHAAA, what a marOON I was !!!

So true. It's funney about a year ago I knew a little about RAID. Mostly linux software raid. Since I started working a QA job at Bluearc testing enterprise level NAS heads I have learned a ton more! However most of it applies only to Enterprise level SAN raids. Heres a pic of the product I test



We have the fastest NAS head out there...we beat Netapp hands down. On a cool note the LOTR films used our product for post processing and rendering

[juneau]

I would love to run my PC off of one of those.

[pigworthy]

Where's the USB Cable connection?

[mapes]

Where's the USB Cable connection?

Well no USB but, our soon to be released Titan 3 product has dual 10GB network interface that can be aggregated into one 20GB network interface. If you look in the pic of my earlier post you'll see two 4U high boxes with funky silver face plates. Each one of those is a Titan. Thats a two node cluster of our product in the pic. We support up to 16 nodes in a cluster. Each node is inter connected vi a redundant dual 10GB network interface and has eight 4 GB fibre Channel interfaces for the back end SAN.