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to RAID or not to RAID (SCSI) .. (Read 3562 times)
Apollon
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to RAID or not to RAID (SCSI) ..
Mar 15th, 2006 at 2:26pm
 
Hi everybody!

Currently I'm running 4 Cheetah 15K.3 HDD with a Tekram 390U3W controller (U160, no RAID) in my desktop computer (no serious work, just a little bit of everything); HDD1: OS, HDD2: swap file, HDD3: applications, HDD4: data. All kept separately and easy manageable.
Now by chance I got the Adaptec 29320LP-R SCSI Card (U320, RAID 0 and 1) for free and I'm wondering if my system would become snappier when using this controller card (in RAID-0 mode) or if I should stick with the "separation approach". The greater risk of losing data with the 0-RAID is not an issue to me. I guess, if I'd just replace the Tekram card with the new one (using no RAID), I wouldn't notice any differende. What do you guys/girls think?

Greetings from Germany, Fritz.
 
 
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Rad
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Re: to RAID or not to RAID (SCSI) ..
Reply #1 - Mar 15th, 2006 at 11:17pm
 
my opinion = only my opinion = raid-0 = double the chance of losing the array cuz you lose everything if 1 drive dries = bad.

raid-1 = a waste of a drive for most home users = bad. there are better ways to back up.
 
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MrMagoo
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Re: to RAID or not to RAID (SCSI) ..
Reply #2 - Mar 16th, 2006 at 12:34am
 
Normally, RAID-0 improves system performance signifcantly.  I was able to cut the boot-up time in half on my computer by raiding my drives (2 Seagate SATA 150 Baracudas.)  Since you are already running Cheetahs, I don't know if your performance gains would be that noticable.  At some point, you will start to bottle-neck on the PCI bus.  But my guess is that you will still notice some extra snappiness.

Personally, it doesn't take me long to reinstall my OS and programs.  I'm not really worried about CD keys and such since Iuse all open-source software, so the only thing I need to back-up is my data.  A 200 GB regular ATA hard drive with a cron job to copy my important files regularly does the trick, so I have no worries about loosing my data if one of my drives goes bad.

RAID does present some extra challenges to some applications (Ghost and BartPE, for example), so be ready to put in some extra effort any time you try something new.
 
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Apollon
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Re: to RAID or not to RAID (SCSI) ..
Reply #3 - Mar 29th, 2006 at 9:08am
 
Re:   Normally, RAID-0 improves system performance signifcantly.

U P D A T E:

When I got the Raid-Card (SCSI Adaptec U320 29320LP-R), I installed it onto my MoBo, started up - and was disappointed. There were no RAID-settings to be made in the Adaptec-BIOS! The reason: this particular card supports no *hardware*-raid but merely *software*-raid. Adaptec calls this HOSTRAID (i.e. crapraid). BEWARE!! (If you visit the Adaptec support-site, you will notice that the 29320LP-R-controller is *not* in the "RAID" listing but in the "U320" listing.)
So today the substitute arrived: Adaptec U160 2100S *real* RAID Controller (Level 0, 1, 5 supported). Installation was fast and very easy. Now I'm running four 15K.3 Cheetah's (which are notoriously quiet) at Raid 0 Level: I'm overwhelmed! My system is  and *feels* so much faster. Only upgrading to broadband internet connection or the first 3D acceleration cards can compete with this experience of gaining speed. It's truly phenomenal. Installing Windows, Windows startup, defrag, etc - it's all enjoyable. I feel like some X to tha Z Xzibit *pimped* my ride Smiley. The downside: working with my Laptop becomes such a drag..

I've been officially "raidified"! Greetings.

 
 
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MrMagoo
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Re: to RAID or not to RAID (SCSI) ..
Reply #4 - Mar 30th, 2006 at 12:28am
 
Thanks for the update.  It's nice to know how it turned out in case I ever consider SCSI and hardware raid.
 
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Raydog
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Re: to RAID or not to RAID (SCSI) ..
Reply #5 - Apr 10th, 2006 at 12:27am
 
Grin A while back when I was lead hardware sales @ CompUSA I remember overhearing one of the shop techs say "Raid Sucks".
I believe this still holds true. The exciting thing for Raid-type performance seekers is the Netcell Revolution SPU cards now made by three companies. The specs are impressive.
 
 
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MrMagoo
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Re: to RAID or not to RAID (SCSI) ..
Reply #6 - Apr 10th, 2006 at 2:48am
 
I'm interested in why you say that RAID sucks.  I got a huge performance out of it and have not had any real trouble.  Would you care to elaborate any?

What are these cards?  Why are they so good?  where can I find information on them?
 
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Scott Peach
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Re: to RAID or not to RAID (SCSI) ..
Reply #7 - May 25th, 2006 at 12:02pm
 
MrMagoo wrote on Apr 10th, 2006 at 2:48am:
I'm interested in why you say that RAID sucks.


As I have set up RAID of many types over dozens computers, I have several emperically derived opinions:

First some terms: RAID 0 I'll call stripe, RAID 1 I'll call mirror, RAID 5 I'll call "pairing" short for collective parity backup, RAID 10 striped & mirrored, and raid 50 striped and paired.

Also important to know are throughput data transfers, like how long to move a video file, vs seek time, like how fast can you find a file, and random access time, like how fast can it move all over the drive collecting bits and pieces.

1) If you have a slow proc, slow hd's, and want to stripe to increase speed, bad idea.  In this case you are likely going with an inexpensive software based raid controller that will suck even more proc power you don't have and while your throughput will be faster, your overall sense of performance will not be a net gain.

2) If you have sufficient funds, fast hardware, and want it faster, than striping IS great as it increases throughput, but not random access or seek times.  So loading, moving or copying large files will see a boost, especially with good well matched hardware.  I recommend automated daily back up to other disks outside of the computer (like a networked massive hd) so the statistically increased chance (2x for 2 drives, 8x for 8 drives etc) of losing the data is of no consequence.

3) If you have a mission critical array that you still want as fast as possible, I personally went with striped and paired.  Using 8 raptors with hot swapable bays (my budget for this project allowed for $2k.  More drives and using Atlas's as would have been faster/bigger/better). I striped 4 pairs doubling throughput and I was able to get 75% capacity storage, but I was still super safe by pairing.  Could the budget have afforded the 12x sata card and 4 more drives, I would have had 83% capacity.  Raid 5/50 is very cool.

4) if money is no object and speed is all there is go with SSD (solid state drives).  These are primarily used in the military (where money is no object) and obviously get VERY expensive quick - $30k for a hard drive is the norm.  Their throughput is a lot faster than normal drives, and still a little faster than the 15k atlas's, but where they really rock is seek times and random access – they are several orders of magnitude faster as the mechanical limit imposed on the normal hd's are removed.  Entusiast level drives are hitting the market like Gigabye i-Ram, DDRDrive and Hyperdrive IV, but cost is still huge.

When we wish to speedup our computers, it is imperative to keep in mind where the bottleneck is.  If you had 1 hr commute to work on the Autobahn, upgrading your Yugo to a Mercedes would significantly improve your commute time.  Go to a Mclaren F1 and it has major improvement again.  But say you commute at the worst possible time in LA, what difference does a faster car make?  An even better analogy is my commute.  Fast roads but a lot of stop lights.  Most of my time is at stop lights.  If I double my speed, I only improve the time between the stop lights, so it takes me 22 min instead of 25 min, even thought I’m driving 2x as fast.  With most computers, HD's are the bottleneck, but not always.  Even when they are, what exactly is the bottleneck about the hd?  Is the random access? Seek time?  Throughput?  It varies by application.  Certainly speeding one thing up doesn't hurt, but if that wasn't our stop light, it might not make a difference.

Albeit fringe tech, it is perfectly acceptable to stripe SSD's, increasing the speed of SSD's "slowest"  aspect.  As a true technolust guy, I plan to stripe a pair of 4gb iRams for the OS portition of my next computer.  I have heard of a sub 5 second windows load time.  Oh baby.

ALL of this was to answer the question - Why would someone say RAID sux.  (damn im longwinded)  I would guess because they thought throughput was their bottleneck, went through expense and trouble of striping some drives, and found out throughput was in fact NOT their bottleneck.

Just my $0.02.

Peach.
 
 
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