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Phoenix32 · 10-14-2006, 01:36 PM

Okay, me being me, I just can't shut up and watch that one pass me by. I have to correct a very common error here.

JBOD is not individual disks, but Sam, who means well and is a good guy, was in fact telling you to set them as individual disks. JBOD is in fact a cousin to RAID. It does stand for "Just a Bunch Of Disks", but that is the point. JBOD is a Bunch Of Disks (2 or more) put into an array to look as if it was a single drive. They are not "stripped", "mirrored", or contain any "parity data", just strung together to look like a single drive. In fact, JBOD is where mixing and matching hard drives is okay because that is what it was designed for. It was originaly designed so that various spare drives laying around on the work benches could be put to good use. What I find interesting is that Adaptec SNAP advertising often lists JBOD as one of the modes supported by their SNAP units (or at least they get advertised that way by others) and yet as far as any SNAP unit I have seen 1st hand, JBOD is not a real option in the menus. Funny thing is, I see this often within advertising of RAID equipments of many manuacturers, and they too do not support this mode. Individual Disks is individual disks, not JBOD. (now off my soap box)

Back on topic...

Tec, as far as I know, if you are using OS version 3.4.805 or above, you can use any size hard disk currently available. Where the limitations are going to come in is the OS, Heat, and Power.

- To go above the LBA 48-bit barrier of 137 GB, you are going to have to use a SNAP OS that supports LBA 48-bit (v3.4.805 and above).

- For Heat, do not use drives that generate a lot of heat and ensure you have good cooling through your SNAPs by making sure you have good fans inside and they are clean etc.

- As for Power, the 12V rail on the SNAP 2x00 OEM power supply is rated at 3A maximum load and you need to take a little out for overhead, say .3A to .5A for fans etc, and it is not a good idea to run a power supply at max load all the time. 70% of max load is a good number to work with for continuous use. So given this info, a little math here, 3A x 70% = 2.1A - .4A = 1.7A. Divide the max load and continuous use numbers by two drives and this leaves you with 12V @ 1.5A startup power and 12V @.85A continuous/use/idle power each for your drives.

So doing the math, based on rated specs, you see the results. 12V @ 1.5A startup power and 12V @.85A continuous/use/idle power. Now with that said, I know for a fact that the Quantum 30 GB drives that were commonly installed in SNAP units, were rated at 1.7A Startup and approximately .5A idle/use. As you can see, that exceeds the max startup power a little. Obviously, the max rated specs on the SNAP 2x00 OEM power supply are a little (I said a little) under rated. Now add to this that many people have been sticking Seagate 250 GB (among others) in these SNAPs, which are rated at 2.5A startup and 1.1A normal idle/use. This means they are running their SNAPs drawing as much as 5.4A on Startup and 2.6A continuous (or 87% maximum load). As a Hardware guy, I have to say this is pushing the limits and not good for longevity, but people are getting away with it most of the time. Keep in mind, every time they shut down and start up that SNAP 2x000, they are running the risk of blowing that power supply (pushing it to almost twice it's max rated limit during drive spin up). Also keep in mind that at 87% of maximum load all the time when it is up and running, that is a lot of strain on the power supply and will cut it's life span. Keeping the SNAP cool inside, and thus the power supply, will help some on that. Also keep in mind that drive power ratings have a tendancy to be a little high because they rate an entire drive family by the highest power drain of any drive in that family as a general rule of thumb (not always).

Now, I am not saying do not put 250, 320, 400, 500 GB drives in there. What I am saying is know the risks. If it were me, I would look for drives using perpendicular recording because they have less platters and thus use less power during spin up and continuous use. If you use Seagate, I would not use 7200.7 or 7200.8 drives as they have higher failure rates and also draw more power and generate more heat. If you really want to research your drives better, go here

http://www.storagereview.com

If you blow one of your SNAP 2x00 OEM power supplies, go here

http://www.northwesttechnical.com

As for how to replace the current drives, here you go.

1. Set drives to INDIVIDUAL DISKS (no RAID arrays)
2. Power down the SNAP
3. Remove slave drive 2
4. Install first new drive
5. Power up SNAP and let it format/init the new drive (might take a little bit)
6. AFTER the new drive is formatted/initialized, turn the SNAP off
7. Remove the master drive 1
8. Install the second new drive
9. Cross fingers
10. Power up SNAP and let it format/init the new drive (might take a little bit)
11. If all went well, you are complete
12. If all did not go well, See David here on the forum
13. Just to be safe, reinstall OS
14. Configure disks as you prefer (Individual, RAID 1, RAID 0)

NOTE: If all did not go well, the most likely cause is the OS being on the drives

So, did that answer the question(s)?

Don't ya'll just love me

10-14-2006, 01:36 PM	#6
Phoenix32 Thermophile Join Date: May 2006 Location: Yakima, WA Posts: 1,282	Re: SNAP 2200 HDD Sizes ? Okay, me being me, I just can't shut up and watch that one pass me by. I have to correct a very common error here. JBOD is not individual disks, but Sam, who means well and is a good guy, was in fact telling you to set them as individual disks. JBOD is in fact a cousin to RAID. It does stand for "Just a Bunch Of Disks", but that is the point. JBOD is a Bunch Of Disks (2 or more) put into an array to look as if it was a single drive. They are not "stripped", "mirrored", or contain any "parity data", just strung together to look like a single drive. In fact, JBOD is where mixing and matching hard drives is okay because that is what it was designed for. It was originaly designed so that various spare drives laying around on the work benches could be put to good use. What I find interesting is that Adaptec SNAP advertising often lists JBOD as one of the modes supported by their SNAP units (or at least they get advertised that way by others) and yet as far as any SNAP unit I have seen 1st hand, JBOD is not a real option in the menus. Funny thing is, I see this often within advertising of RAID equipments of many manuacturers, and they too do not support this mode. Individual Disks is individual disks, not JBOD. (now off my soap box) Back on topic... Tec, as far as I know, if you are using OS version 3.4.805 or above, you can use any size hard disk currently available. Where the limitations are going to come in is the OS, Heat, and Power. - To go above the LBA 48-bit barrier of 137 GB, you are going to have to use a SNAP OS that supports LBA 48-bit (v3.4.805 and above). - For Heat, do not use drives that generate a lot of heat and ensure you have good cooling through your SNAPs by making sure you have good fans inside and they are clean etc. - As for Power, the 12V rail on the SNAP 2x00 OEM power supply is rated at 3A maximum load and you need to take a little out for overhead, say .3A to .5A for fans etc, and it is not a good idea to run a power supply at max load all the time. 70% of max load is a good number to work with for continuous use. So given this info, a little math here, 3A x 70% = 2.1A - .4A = 1.7A. Divide the max load and continuous use numbers by two drives and this leaves you with 12V @ 1.5A startup power and 12V @.85A continuous/use/idle power each for your drives. So doing the math, based on rated specs, you see the results. 12V @ 1.5A startup power and 12V @.85A continuous/use/idle power. Now with that said, I know for a fact that the Quantum 30 GB drives that were commonly installed in SNAP units, were rated at 1.7A Startup and approximately .5A idle/use. As you can see, that exceeds the max startup power a little. Obviously, the max rated specs on the SNAP 2x00 OEM power supply are a little (I said a little) under rated. Now add to this that many people have been sticking Seagate 250 GB (among others) in these SNAPs, which are rated at 2.5A startup and 1.1A normal idle/use. This means they are running their SNAPs drawing as much as 5.4A on Startup and 2.6A continuous (or 87% maximum load). As a Hardware guy, I have to say this is pushing the limits and not good for longevity, but people are getting away with it most of the time. Keep in mind, every time they shut down and start up that SNAP 2x000, they are running the risk of blowing that power supply (pushing it to almost twice it's max rated limit during drive spin up). Also keep in mind that at 87% of maximum load all the time when it is up and running, that is a lot of strain on the power supply and will cut it's life span. Keeping the SNAP cool inside, and thus the power supply, will help some on that. Also keep in mind that drive power ratings have a tendancy to be a little high because they rate an entire drive family by the highest power drain of any drive in that family as a general rule of thumb (not always). Now, I am not saying do not put 250, 320, 400, 500 GB drives in there. What I am saying is know the risks. If it were me, I would look for drives using perpendicular recording because they have less platters and thus use less power during spin up and continuous use. If you use Seagate, I would not use 7200.7 or 7200.8 drives as they have higher failure rates and also draw more power and generate more heat. If you really want to research your drives better, go here http://www.storagereview.com If you blow one of your SNAP 2x00 OEM power supplies, go here http://www.northwesttechnical.com As for how to replace the current drives, here you go. 1. Set drives to INDIVIDUAL DISKS (no RAID arrays) 2. Power down the SNAP 3. Remove slave drive 2 4. Install first new drive 5. Power up SNAP and let it format/init the new drive (might take a little bit) 6. AFTER the new drive is formatted/initialized, turn the SNAP off 7. Remove the master drive 1 8. Install the second new drive 9. Cross fingers 10. Power up SNAP and let it format/init the new drive (might take a little bit) 11. If all went well, you are complete 12. If all did not go well, See David here on the forum 13. Just to be safe, reinstall OS 14. Configure disks as you prefer (Individual, RAID 1, RAID 0) NOTE: If all did not go well, the most likely cause is the OS being on the drives So, did that answer the question(s)? Don't ya'll just love me Last edited by Phoenix32; 10-14-2006 at 02:19 PM.