Re: [luau] Software RAID (Donation of Oracle 9i Linux)
I'm thinking about using NFS and NIS+ to keep these server accounts in sync with the Sun Enterprise 450 a few doors down running the SunRay lab, but I am worried about security between the two rooms. Some genius used HUBS across a large portion of the campus, so security of NFS and NIS+ over the existing network would be quite bad. Would this work over a cheap, direct cross-over link between the two rooms? Then I guess the only problem would be the very expensive additional 100mbit Ethernet interface for the Sun E450. =( We are about to implement rsync to keep our fleet of servers current with one another. I like the algorithm, security, and speed of it. It sounds like it may work well for this task I can help in any way possible. scott
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
W. Wayne Liauh wrote: What would be the point of doing a RAID with 1 drive :) You get 0 redundency. True, in theory. But suppose you are working on a 1,000 page leagl brief, then all of a sudden you hid a bad sector in your hard drive which causes your document to become corrupted? A new question. Will the same-drive RAID help in a virus infested situation? For example, suppose I downloaded a Microsoft Word .doc file which contains a macro virus. Will this Microsoft virus do the same damages on the redundent partition? Of course it will. RAID makes copies of everything, below the filesystem layer. A RAID array ensures that both disks are identical. While on the subject, I would NOT reccomend doing RAID on a single disk with different partitions: it would be slower than you would believe. RAID has to make sure all devices have committed the info before it can continue (to keep the array consistant, of course hardware raids with battery backup can work around this with lots of cache and keeping the disks up to date minus cache). This would cause massive disk seeks every time the drive was accessed, killing performance. --MonMotha
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
of course hardware raids with battery backup can work around this with lots of cache and keeping the disks up to date minus cache). Help me with this one. I built a server with a hardware raid controller. I noticed that Adaptec offers a backup battery module for it, but I don't understand the scenario when it would be used. If the card can't get power from the motherboard, then there is likely no power to the drives. I know I don't understand something here, can you enlighten me. :-) scott
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
R. Scott Belford wrote: of course hardware raids with battery backup can work around this with lots of cache and keeping the disks up to date minus cache). Help me with this one. I built a server with a hardware raid controller. I noticed that Adaptec offers a backup battery module for it, but I don't understand the scenario when it would be used. If the card can't get power from the motherboard, then there is likely no power to the drives. I know I don't understand something here, can you enlighten me. :-) scott In order for the array to be redundant, all drives must be consistant with each other. This means that the raid controller/software can't continue with the next operation until ALL devices have completed the previous one (SCSI can queue up multiple operations, but the write isn't done until ALL drives in the array are at the same state). In order to compensate for this, many big RAID cards (like my AMI MegaRAID) have a battery backed RAM cache. If the power goes out, all the drives are in a consistant state (as assured by the controller) with each other, but not nesecarilly with what the OS thought it was. The cache has to be maintained across resets to keep the array in a consistant state if cache is to be used (and believe me, it helps performance tremendously). This is why the cards have a battery. DRAM (and some cards use SRAM) takes VERY little power, so a tiny little battery pack can keep it powered for a very long time (days, months, etc), ensuring that the cache data isn't lost in the event of an unclean power down. This is always a good idea. --MonMotha
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
I see and I understand. Thanks for the time taken to respond. I can justify the expense for the battery now that I understand what I need it for. It really does sound like I need it if I am serious about data integrity in all worse case scenarios. scott
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
With a RAID1 it is mirrored. This means that if you write a file to 1 drive, it will be added to the other. This will protect your system from going down. If 1 drive fails, the other drive is working. This also means that if a file is downloaded and is virused, it still will affect your system :) Brian What would be the point of doing a RAID with 1 drive :) You get 0 redundency. True, in theory. But suppose you are working on a 1,000 page leagl brief, then all of a sudden you hid a bad sector in your hard drive which causes your document to become corrupted? A new question. Will the same-drive RAID help in a virus infested situation? For example, suppose I downloaded a Microsoft Word .doc file which contains a macro virus. Will this Microsoft virus do the same damages on the redundent partition? ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau
RE: [luau] Software RAID (Donation of Oracle 9i Linux)
Not really :) You can do a RAID1 with 2 drives (mirror) a RAID5 with 3 Drives (4 is recomend 3 for the RAID 1 as a spare) Brian -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of W. Wayne Liauh Sent: Thursday, August 15, 2002 1:38 PM To: [EMAIL PROTECTED] Subject: [luau] Software RAID (Donation of Oracle 9i Linux) Can you do a software RAID with just one HD? ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
W. Wayne Liauh wrote: Not really :) Just thought that with the current advancement of multiple-head HDs, things might have changed. But I suppose if someone can develop a new type of BIOS? Most consumer grade IDE hard drives don't support reading from multiple heads at the same time, not that it would matter much as IDE drives can only do one thing at once, before they return the result to the system. SCSI drives of course have tagged command queueing, and I seem to recall that some allow reading from multiple heads at once, but it is controlled by the drive's firmware, not the PC host. RAID, by definition, is a Redundant Array of Inexpensive Devices. Normally these devices are whole packages, not pieces parts inside a single unit. --MonMotha
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
In litteral terms, you can do software raid on linux with 1 HD and two partitions. However, it probably hurts performance, rather than improving it. The multiple heads on a hard drive all line up vertically and scan what's called a cyllinder (multiple sectors stacked on top of each other). They cannot read two partitions at the same time. You could test out software raid with two partitions, but I don't think you'd be too happy with it. You can probably get RAID 1 going with a very slight advantage. It won't save you in case your drive fails entirely, but if you start to get bad sectors or filesystem errors, at least your HD is backed up on another partition. -Eric Hattemer - Original Message - From: W. Wayne Liauh [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, August 15, 2002 1:54 PM Subject: [luau] Software RAID (Donation of Oracle 9i Linux) Not really :) Just thought that with the current advancement of multiple-head HDs, things might have changed. But I suppose if someone can develop a new type of BIOS? ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau
RE: [luau] Software RAID (Donation of Oracle 9i Linux)
What would be the point of doing a RAID with 1 drive :) You get 0 redundency. Brian -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Eric Hattemer Sent: Thursday, August 15, 2002 2:53 PM To: [EMAIL PROTECTED] Subject: Re: [luau] Software RAID (Donation of Oracle 9i Linux) In litteral terms, you can do software raid on linux with 1 HD and two partitions. However, it probably hurts performance, rather than improving it. The multiple heads on a hard drive all line up vertically and scan what's called a cyllinder (multiple sectors stacked on top of each other). They cannot read two partitions at the same time. You could test out software raid with two partitions, but I don't think you'd be too happy with it. You can probably get RAID 1 going with a very slight advantage. It won't save you in case your drive fails entirely, but if you start to get bad sectors or filesystem errors, at least your HD is backed up on another partition. -Eric Hattemer - Original Message - From: W. Wayne Liauh [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, August 15, 2002 1:54 PM Subject: [luau] Software RAID (Donation of Oracle 9i Linux) Not really :) Just thought that with the current advancement of multiple-head HDs, things might have changed. But I suppose if someone can develop a new type of BIOS? ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
Add RAID to 4 drives better. I have 5-20gb hdds and have RAID on the last 4. You cant add RAID to the hdd you have the OS installed. I have 1,5. Good to have Parity especially with the electrical systems here in Hawaii where the average lifespan of a P/S is 1 1/2 years. Too much flux in the voltage. - Original Message - From: Brian Low [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, August 15, 2002 3:23 PM Subject: RE: [luau] Software RAID (Donation of Oracle 9i Linux) What would be the point of doing a RAID with 1 drive :) You get 0 redundency. Brian -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Eric Hattemer Sent: Thursday, August 15, 2002 2:53 PM To: [EMAIL PROTECTED] Subject: Re: [luau] Software RAID (Donation of Oracle 9i Linux) In litteral terms, you can do software raid on linux with 1 HD and two partitions. However, it probably hurts performance, rather than improving it. The multiple heads on a hard drive all line up vertically and scan what's called a cyllinder (multiple sectors stacked on top of each other). They cannot read two partitions at the same time. You could test out software raid with two partitions, but I don't think you'd be too happy with it. You can probably get RAID 1 going with a very slight advantage. It won't save you in case your drive fails entirely, but if you start to get bad sectors or filesystem errors, at least your HD is backed up on another partition. -Eric Hattemer - Original Message - From: W. Wayne Liauh [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, August 15, 2002 1:54 PM Subject: [luau] Software RAID (Donation of Oracle 9i Linux) Not really :) Just thought that with the current advancement of multiple-head HDs, things might have changed. But I suppose if someone can develop a new type of BIOS? ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
There is little point. I'm sure someone can think of an absurd situation in which it might help, but its just interesting that the linux kernel allows software raid on a partition by partition basis, even if the two partitions are on the same drive. Its actually quite useful in that you can set up 2 hard drives each with a linux partition and a windows partition, then set linux to do software raid on it. That's what I always do. Windows software raid takes over both hard drives, then requiers a third because it makes them non-bootable. Really a backup device beats any system of 1HD software raid 1, but it might be fun to mess around with if you're bored. Certainly setting up software raid 0 can be fun on a desktop system, though. That's what I do, and I'm quite happy with it as long as redhat sets the DMA on (I always have to force it on on two different motherboards because of its over ambitious bad controller protection). -Eric Hattemer - Original Message - From: Brian Low [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, August 15, 2002 3:23 PM Subject: RE: [luau] Software RAID (Donation of Oracle 9i Linux) What would be the point of doing a RAID with 1 drive :) You get 0 redundency. Brian -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Eric Hattemer Sent: Thursday, August 15, 2002 2:53 PM To: [EMAIL PROTECTED] Subject: Re: [luau] Software RAID (Donation of Oracle 9i Linux) In litteral terms, you can do software raid on linux with 1 HD and two partitions. However, it probably hurts performance, rather than improving it. The multiple heads on a hard drive all line up vertically and scan what's called a cyllinder (multiple sectors stacked on top of each other). They cannot read two partitions at the same time. You could test out software raid with two partitions, but I don't think you'd be too happy with it. You can probably get RAID 1 going with a very slight advantage. It won't save you in case your drive fails entirely, but if you start to get bad sectors or filesystem errors, at least your HD is backed up on another partition. -Eric Hattemer - Original Message - From: W. Wayne Liauh [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, August 15, 2002 1:54 PM Subject: [luau] Software RAID (Donation of Oracle 9i Linux) Not really :) Just thought that with the current advancement of multiple-head HDs, things might have changed. But I suppose if someone can develop a new type of BIOS? ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
You cant add RAID to the hdd you have the OS installed. I have 1,5. Good to You actually can add raid to the hard drive where you have the OS installed in most modern distros. Its a bit tricky in the old ones. The old ones require that you install to a different hard drive, then set up a software raid table, then move the system to the raid array, then edit the fstab, then reboot. This is a lot of work. In systems after about RH 7.1, the graphical install allows you to put / on a software raid array. Usually what you'll want to do, however, is make one partition on the first drive be the /boot partition (non-raid) just to make kernel configuration easier. Then put / on the raid array. You can get some of the performance bonuses from raid 0/5 by putting /usr, /home, /bin, /opt and whatever on separate drives if you have a big enough system. -Eric Hattemer Brian -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Eric Hattemer Sent: Thursday, August 15, 2002 2:53 PM To: [EMAIL PROTECTED] Subject: Re: [luau] Software RAID (Donation of Oracle 9i Linux) In litteral terms, you can do software raid on linux with 1 HD and two partitions. However, it probably hurts performance, rather than improving it. The multiple heads on a hard drive all line up vertically and scan what's called a cyllinder (multiple sectors stacked on top of each other). They cannot read two partitions at the same time. You could test out software raid with two partitions, but I don't think you'd be too happy with it. You can probably get RAID 1 going with a very slight advantage. It won't save you in case your drive fails entirely, but if you start to get bad sectors or filesystem errors, at least your HD is backed up on another partition. -Eric Hattemer - Original Message - From: W. Wayne Liauh [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, August 15, 2002 1:54 PM Subject: [luau] Software RAID (Donation of Oracle 9i Linux) Not really :) Just thought that with the current advancement of multiple-head HDs, things might have changed. But I suppose if someone can develop a new type of BIOS? ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau ___ LUAU mailing list [EMAIL PROTECTED] http://videl.ics.hawaii.edu/mailman/listinfo/luau
Re: [luau] Software RAID (Donation of Oracle 9i Linux)
Eric Hattemer wrote: You cant add RAID to the hdd you have the OS installed. I have 1,5. Good to You actually can add raid to the hard drive where you have the OS installed in most modern distros. Its a bit tricky in the old ones. The old ones require that you install to a different hard drive, then set up a software raid table, then move the system to the raid array, then edit the fstab, then reboot. This is a lot of work. In systems after about RH 7.1, the graphical install allows you to put / on a software raid array. Usually what you'll want to do, however, is make one partition on the first drive be the /boot partition (non-raid) just to make kernel configuration easier. Then put / on the raid array. You can get some of the performance bonuses from raid 0/5 by putting /usr, /home, /bin, /opt and whatever on separate drives if you have a big enough system. -Eric Hattemer Depends on the RAID level. If you are starting from single drive, and you want to go to a RAID level that is redundant (1, 4, or 5...anything but 0), what you can do is configure the array with the drive currently in use as a failed disk, meaning that when it initilizes the array, it will bring it up in degraded mode, not using the disk that you're currently on. You then copy everything over, reboot onto the new array (still in degraded mode) and raidhotadd in the last disk. This is how I converted my slack system to RAID 5. --MonMotha
