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RAID card for my PC??
I have a ton of files (50 gig and growing) that I am very tired of backing up
and managing. I saw a RAID card for $60 for a PC that runs 2 mirrored hard drives. Also saw 120 gig hard drives for $60. Hmmm… for $180 I get true RAID with BIG drives in my desktop! This means that I don't have to make periodic CD backups nearly so often. Change something on one drive and it gets done on both without me having to think about it. And it is very unlikely that both drives will go down at once. What happens if one drive dies? Does the other one seamlessly take over, or must the PC be rebooted? Do I have to take it apart to swap cables, or would it just keep running? If it just keeps running, how do I know that a drive is dead? Are there any drawbacks to running RAID on a PC? Anyone have experience mirroring drives like this? Your comments appreciated. thanks |
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TANKIE said in :
I have a ton of files (50 gig and growing) that I am very tired of backing up and managing. I saw a RAID card for $60 for a PC that runs 2 mirrored hard drives. Also saw 120 gig hard drives for $60. Hmmm. for $180 I get true RAID with BIG drives in my desktop! This means that I don't have to make periodic CD backups nearly so often. Change something on one drive and it gets done on both without me having to think about it. And it is very unlikely that both drives will go down at once. What happens if one drive dies? Does the other one seamlessly take over, or must the PC be rebooted? Do I have to take it apart to swap cables, or would it just keep running? If it just keeps running, how do I know that a drive is dead? Are there any drawbacks to running RAID on a PC? Anyone have experience mirroring drives like this? Your comments appreciated. thanks You have confused mirroring with backup. Mirroring won't give you backup for your files. The mirror drive gives you the same files as on your primary drive. Also, writes will be slowed slightly (because it must write the same data to 2 drives) but reads may be sped up if round-robin read access is used. Mirroring is a *hardware* backup in that it lets you recover from hardware disaster. While software RAID may perform logical file reads to copy the files onto the mirror drive, I have to wonder (but don't know) if hardware mirroring might not end up giving you an exact mirror on a sector basis. That means if the registry is screwed up on the primary than your "backup" on the mirror drive is also corrupted. If your file system is corrupted then it is also corrupted on the mirror drive. If hardware is used for mirroring and if hardware mirroring makes an EXACT copy then it gets just as screwed up as the primary drive. Mirroring is meant to let you quickly get your system back to its prior state but only to that exact prior sta te. If you want backups, and to recover your system to an exact state as before, get disk imaging software (DriveImage, Ghost, and I hear BingNT makes disk images, too). You could get software that makes .iso disk images but there is no compression. Ghost also has problems in that you need to use the /IA switch to do a save of a physical disk image (that reads sectors) rather than a logical one (that reads the files), but it won't skip unused sectors and so it wastes space recording them. While disk images are great for restoring your system to a known prior (and probably good) state, disk images are a pain to use when you just want to recover a few files, like your Word doc or a DLL file that goes missing. DriveImage has its ImageExplorer to extract files from its disk image fileset but it becomes very slow if you need to extract thousands of files from a directory, like for all your clipart, and appears to have problems extracting logical files from the physical image for those that were EFS protected). So you'll still probably want to use NT Backup or a 3rd party backup program to save logical copies of, at least, your data files. Use mirroring for physical recovery (i.e., hardware disaster recovery) to get your computer back up quickly. Use disk images to provide you a means of taking snapshots of your drive for recovery from logical errors. If you want backups, use that 2nd drive as where you save disk images and file backups. However, this 2nd drive will always be spinning. Or, if removable, is still prone to mechanical failure. So use it only for the most recent set of disk images and file backups from where you copy them later onto removable media as you rotate through them. Even if the backup hard drive fails, you'll still have the removable media to use in another same-type drive or in a replacement drive, so at most you lose one backup set if the hard drive fails. Of course, if you only save one disk image and/or one file backup then it needs to go onto removable media rather than a hard drive which is far more prone to fail. Nothing like months down the road then finding out your backup drive has "soft" sectors with reduced retentivity that generate errors on reads made months or years after the writes. When using removable media, ALWAYS enable the option to verify it contents. Backup media that hasn't been verified that what it contains is what got written to it often results in some very dire consequences later when and only then you find you cannot read from that removable media, akin to throwing spare batteries in your travel kit only to find while on vacation in some remote location that the batteries were dead. So decide whether you want to backup your files (as disk images or file backups) or whether you want to backup the availability of your computer (with mirroring). For a work desktop computer with critical development performed on it or when used as a server, uptime is very important. For a home computer, uptime is not critical and you just go get a replacement drive on which you restore whatever snapshot (disk image) or file backup you want. Hard drive die just through normal use but removable media dies when it has been physically abused, so don't rely entirely on a hard drive to let you restore a snapshot or files. I've seen users that thought it was cool and easy to use a USB-connected hard drive onto which they did a drive copy, saved one or more disk images, or saved backup filesets only to later find the drive went dead or got jarred enough so that it wasn't usable anymore and all their backups were gone. Use the hard drive only as the first device in a rotation set so you only have to explain or suffer the loss of just those backups and still go back to removable media for the prior backup. Yes, the two hard drives are not likely to fail at the same time - unless the damage is common to both, like a PSU that goes beserk and outputs too-high voltages (I got nailed by one but a long time ago), a power surge, ESD at the controller or motherboard that runs up the common cable to both drives, and so on. But then mirroring doesn't give you backup (of your files). It just gives you quick recovery from hardware failure. Although I save disk images, I also save file backups because often I want to get at just one or few of my old data files. Note that the NT Backup program will NOT compress your file backups. It only has the option to *enable* compression if the [tape] device supports it. It does do any compression on its own. You'll need a 3rd party backup program that includes compression regardless onto what media it writes its backup fileset. Also note that if you use the 2nd hard drive for backups (instead of mirroring) using disk images that you will need to configure your disk imaging software to slice up the disk image files into sizes that will fit onto whatever removable media that you plan to later move that snapshot fileset. For example, if you later intend to save the disk image from the hard drive onto CD-R media then make sure the disk image program creates files that are 650MB maximum in size. -- __________________________________________________ __________ *** Post replies to newsgroup. Share with others. *** Email: domain = ".com" and append "=NEWS=" to Subject. __________________________________________________ __________ |
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#4
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The RAID card that you are talking about does NOT offer data redundency.
You have to get a much more expensive card for that. If your RAID 0 setup that you are considering has a harddrive fail, ALL data will be lost. -- DaveW "TANKIE" wrote in message ... I have a ton of files (50 gig and growing) that I am very tired of backing up and managing. I saw a RAID card for $60 for a PC that runs 2 mirrored hard drives. Also saw 120 gig hard drives for $60. Hmmm. for $180 I get true RAID with BIG drives in my desktop! This means that I don't have to make periodic CD backups nearly so often. Change something on one drive and it gets done on both without me having to think about it. And it is very unlikely that both drives will go down at once. What happens if one drive dies? Does the other one seamlessly take over, or must the PC be rebooted? Do I have to take it apart to swap cables, or would it just keep running? If it just keeps running, how do I know that a drive is dead? Are there any drawbacks to running RAID on a PC? Anyone have experience mirroring drives like this? Your comments appreciated. thanks |
#5
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"DaveW" schreef in bericht
news6wrc.36228$gr.3620517@attbi_s52... The RAID card that you are talking about does NOT offer data redundency. You have to get a much more expensive card for that. If your RAID 0 setup that you are considering has a harddrive fail, ALL data will be lost. + people often forget the most important reason why taking backups: user stupidity. "Oops, I deleted that file. Now I still need it." No RAID level can fix this ... J. |
#6
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On Fri, 21 May 2004 23:17:40 GMT, "DaveW" wrote:
The RAID card that you are talking about does NOT offer data redundency. You have to get a much more expensive card for that. If your RAID 0 setup that you are considering has a harddrive fail, ALL data will be lost. Untrue, even the cheap SiI $15 cards do RAID1. |
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