I'm gonna try this this weekend. I might pickup a few more sticks since I only have 1 2gb, 1 1gb and an old 512mb stick from who knows when lol. Nice idea OP.
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Poor mans SSD ;-)
- Thread starter EdbBob
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Well it's running
To speed it up:1. Check that you have two sticks on each bus. You can see what sticks are on what bus in System Profiler.
2. Try to copy a large file to and from the raid to see what performance the raid has. Open activity monitor, press CMD+1 and look under Disk Activity. What's the performance?
3. What other Peripherals do you have on the usb ports? My usb tv tuner takes some bandwith when it's running.
Did you measure the speed of one of your sticks before raiding them? To have a decent performance from 4 sticks they'll have to be pretty fast. Otherwise you need more sticks.
Hope it helps
Raid0 is normally (with HDD's) mostly used to gain speed, whereas it has no built in safety in case of one drive going down. Because all data are spread across the raid one drive failure means that the hole raid becomes unreadable. This is actually an interesting feature with the flash raids. If you shut your computer down and bring one of the sticks your wife can't read your mail or check your dirty downloads
One of the major differences between HDD's and SSD's are that HDD's normally fail during reads while SSD's normally fail during write (but they are probably still readable). That should make raid0 a lot safer with a flash raid.
Raid1 is a simple mirror of one drive to another. You can combine raid0 and raid1 giving you raid1+0 wich has slightly slower perf than raid0 with half the capacity. I havent been able to try that yet, and I'm not sure it's possible as a software raid in OS X, but if anybody knows how to set it up please let us know?
Raid5 is the smart solution. It uses one drive as a parity drive and the rest of the drives for data. Good perf and almost same capacity as raid0, but in OS X, I don't think it's possible with a software raid. Again if anybody knows different let me know...
For now, I think the best solution for the flash raid is to use Time Machine to back it up. That's one of the best backup programs I've ever seen. One thing though: You'll probably use an external disk for backup, and that should possibly be a firewire disk for best performance of the raid.
I don't think this is tested enough to run serious applications yet, so be careful out there. I have yet to see what happens when a stick becomes unwriteable... But I've had it running for some days now, and it seems pretty solid
Awesome idea.
If its quite slow its probably because you paid $10 for an 8gb Flash drive.
I paid $40 for a 2gb drive not so long ago, but its amazingly fast.
I thought OS X only installed on Firewire external drives? Well thats news to me, will have to give it ago sometime.
If its quite slow its probably because you paid $10 for an 8gb Flash drive.
I paid $40 for a 2gb drive not so long ago, but its amazingly fast.
I thought OS X only installed on Firewire external drives? Well thats news to me, will have to give it ago sometime.
I actually paid 27.99 each for the 4 8gb stick. I don't have a firewire port on the new macbook, only USB's.
I have them all on 1-4 port hub now, I will try to spread them out over the 2 hubs, and see if that makes a diff.
Update: Just tried 2 on each hub, and got a performance of 33MB/s write from my internal HDD, and 45MB/s read from the USB raid to the internal HDD. not so bad I guess. It feels alot peppier now that I moved across the 2 diff hubs.
Now i am wondering if I should get another 4 sticks for 120.00 bucks, or return the 8gig sticks and get 8-4gig sticks for slightly more money/ better performance. This is just an experiment, and not at all gonna be something I stick with long term. Its pretty cool. If i really like it I might spring for the 128GB SSD, to replace my 250 5400rpm.
Well is saying more reliable, you actually mean less reliable, due to the nature of the flash drive, this is a raid 0 were are talking about.
wow this is really interesting!
so in a way if you make a RAID flash drive you can use it as a backup OS if something ever happens? (thats if you install OS X on it) i might try this except i'll use it as a hard drive for storing data
so in a way if you make a RAID flash drive you can use it as a backup OS if something ever happens? (thats if you install OS X on it) i might try this except i'll use it as a hard drive for storing data
I think you can get away alot cheaper per GB if you just got a standard hard drive for external backup. You are looking at 100GB for less than $100.00 for a hard drive, whereas a flash drive RAID is gonna cost ya at least 100.00 for like 32GB.
Raid0 is normally (with HDD's) mostly used to gain speed, whereas it has no built in safety in case of one drive going down. Because all data are spread across the raid one drive failure means that the hole raid becomes unreadable. This is actually an interesting feature with the flash raids. If you shut your computer down and bring one of the sticks your wife can't read your mail or check your dirty downloads
One of the major differences between HDD's and SSD's are that HDD's normally fail during reads while SSD's normally fail during write (but they are probably still readable). That should make raid0 a lot safer with a flash raid.
Raid1 is a simple mirror of one drive to another. You can combine raid0 and raid1 giving you raid1+0 wich has slightly slower perf than raid0 with half the capacity. I havent been able to try that yet, and I'm not sure it's possible as a software raid in OS X, but if anybody knows how to set it up please let us know?
Raid5 is the smart solution. It uses one drive as a parity drive and the rest of the drives for data. Good perf and almost same capacity as raid0, but in OS X, I don't think it's possible with a software raid. Again if anybody knows different let me know...
For now, I think the best solution for the flash raid is to use Time Machine to back it up. That's one of the best backup programs I've ever seen. One thing though: You'll probably use an external disk for backup, and that should possibly be a firewire disk for best performance of the raid.
I don't think this is tested enough to run serious applications yet, so be careful out there. I have yet to see what happens when a stick becomes unwriteable... But I've had it running for some days now, and it seems pretty solid
Ed, very cool ! I actually did this a long time ago with LS-120 mag/optical drives for fun ... only 4 of them :-(
I will make a slight correction here about RAID5. RAID 5 doesn't designate a single disk for parity; it does use one drive worth of space for parity in the array but the parity is rotated throughout the array .. spread out on each disks interleaved with the data blocks. It's a minor nit but it does matter at some level. RAID 5 is giving way to dual parity schemes now like raid 6 or RAID DP.
If you want the good performance and still want some data protection from a drive failing, I second your recommendation of using RAID 1+0
I'm still a Mac newbie so I don't even know if you can make a RAID 1+0 array from disk utility. Can you?Take care,
sa
Hey there
Nice! 42 MB/s must be at least as good as a 5400 rpm 2.5" disk in a MacBook.Well 42 MB/s with 4 sticks should give close to 84 M/s with 8 sticks if my theory is correct and they are equally separeted on two usb busses. 84 MB/s is like having a 10.000 rpm WD Raptor wich is considered the fastest sata HDD. Not bad for 200§ i think
I've had 3 sticks running at 50 MB/s on one bus so i still think 8 A-data 200x sticks will max out read performance at about 100 MB/s when the bus is quiet from other devices (keyb and mouse doesn't affect perf).It all depends on the speed of the sticks. If 4 and 8 GB sticks have the same speed, 8x4 GB gives twice the performance as 4x8, but a 32 GB system drive is to small for me as I want to install applications as well.
From what I've seen with Kingstons 8 GB are far faster than 1 GB when it comes to write perf. Dunno about 4 GB.
One last thought: Since USB doesn't use interrupts, I have a gut feeling that as few sticks as possible, to max out the busses is optimal. But I could be wrong
Yep you could do that. Or use different raids for serious work and fooling around with geeky software. The possibilities are endless
A backup OS could easily run on two fast sticks if it's only used for "system maintenance".True, but don't forget that IF it's possible to have a 100 MB/s with no access time we are talking high end SSD performance wich is a lot more expensive, and I can use it on my iMac with usb without taking the machine apart... Using it for backup doesn't really make sence. We're talking cheap speed, not cheap storage. (Poor man's SSD ;-)
Ed, very cool ! I actually did this a long time ago with LS-120 mag/optical drives for fun ... only 4 of them :-(
I will make a slight correction here about RAID5. RAID 5 doesn't designate a single disk for parity; it does use one drive worth of space for parity in the array but the parity is rotated throughout the array .. spread out on each disks interleaved with the data blocks. It's a minor nit but it does matter at some level. RAID 5 is giving way to dual parity schemes now like raid 6 or RAID DP.
If you want the good performance and still want some data protection from a drive failing, I second your recommendation of using RAID 1+0
Take care,
sa
Thanks, didn't know that! I've mostly fooled around with raid0 since i work with film compositing and that means a lot of MB/s. Always wanted raid5 but I was not willing to pay for a hardware raid controller just to have safety
Call me a greedy bastard, but "a computer cant be cheap or fast enough"Gotta wiki raid5 some more. Wiki is the true source of all good info! And info wants to be free...
Btw. EdbBob is a nick name because EDB in danish meant Electronic Data Treatment in the 70's and I ride a 1948 Bobber, leading to the rest of the nickname. A calculator was called an "Electron Brain"
found out that the sticks I had were very slow, but were performing as specificed. I am getting 4 more 8 gig sticks, and returning the bestbuy ones. I have been looking around on the net for the fastest ones. It looks like the Corsair voyager GT seems to be the fastest @ 35mB/s read 28mB/s write. I ca max out each bus with 2 sticks, each bus being 60mB/s
In theory, yes
Corsair also promise that you can write to them for 10 years, 24/7! Looking forward to hear about those. And, they look kind of cool Update: 75 MB/s from USB Memory Sticks
I've received enough sticks from A-data to perform a test with 8x8 GB in raid0. The sticks are PD7 200x 8 GB. They are mounted via two Trust HU-5770 USB Hubs each connected to one separate USB bus on my iMac.
It's getting more difficult to benchmark this because the raid is so fast that the disk I'm writing to is the bottleneck, so I tried to playback a HD 1080 uncompressed TGA sequence form the raid using Framecycler.
The results are promising. 75 MB/s! That's possibly the most data pulled through usb on an iMac ever! Write is about 50 MB/s. To compare that, playing back the same sequence from a 2 TB Raid0 running on the FW800 port gives me about 53 MB/s read speed, wich means that the flash raid is about 41% faster!!! Not bad
I don't know if this is max performance of a flash raid but I'll have to find a sponsor and build an even bigger raid
Next thing to do is to install OS X Leopard (or should I go for Snow Leopard?!?) Back in a few hours with more results.
Thanks for all your the interest in this little experiment. "I can live for two months on a good compliment." - Mark Twain
I've received enough sticks from A-data to perform a test with 8x8 GB in raid0. The sticks are PD7 200x 8 GB. They are mounted via two Trust HU-5770 USB Hubs each connected to one separate USB bus on my iMac.
It's getting more difficult to benchmark this because the raid is so fast that the disk I'm writing to is the bottleneck, so I tried to playback a HD 1080 uncompressed TGA sequence form the raid using Framecycler.
The results are promising. 75 MB/s!
That's possibly the most data pulled through usb on an iMac ever! Write is about 50 MB/s. To compare that, playing back the same sequence from a 2 TB Raid0 running on the FW800 port gives me about 53 MB/s read speed, wich means that the flash raid is about 41% faster!!! Not bad I don't know if this is max performance of a flash raid but I'll have to find a sponsor and build an even bigger raid
Next thing to do is to install OS X Leopard (or should I go for Snow Leopard?!?
) Back in a few hours with more results.Thanks for all your the interest in this little experiment. "I can live for two months on a good compliment." - Mark Twain