Re: Replacement RAID hard drives - do they have to be clean?
Ken Heard kensli...@teksavvy.com writes: One of my boxes has a RAID1 using two Seagate SATA 3.0 1 tb hard drives. I need to replace one of them, and I would like to use as a replacement a Samsung SATA 2.0 1 tb drive which already has on it data which I do not need to keep. My first question is: although both drives are the same size, can I get away with having one drive a Seagate 3.0 and the other Samsung 2.0? That depends on your RAID controller. It occurred to me that if I made the change described in the first paragraph -- but without somehow making the data already on it unreadable -- there would be a different data set on each drive; so that the RAID1 software would not necessarily know which drive should be the data source to copy to the other drive. It also occurred to me that the software could combine the data on each drive, so that both drives would have both data sets. That depends on your RAID controller. It's probably a very good idea to clean the drive before plugging it in. Clean the drive would mean to use something like dd to overwrite the whole drive with zeroes. I consequently assume that the data on the replacement drive must somehow be made unreadable. Is that assumption correct? If so, do the data have to be shredded, or is it sufficient simply either to delete them or simply reformat the drive? To actually delete all data on a disk beyond all recoverability, you basically have to melt down the drive. Modern drives usually don't allow you to format them. Finally, once I have a clean new drive installed, will the RAID1 copying process partition the new drive the same way as the other drive and copy the files without further human intervention? That depends on your RAID controller. At least it should rebuild the RAID once you told it to use the disk as a replacement for the old one. -- Knowledge is volatile and fluid. Software is power. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/878ulddjtq@yun.yagibdah.de
Re: Replacement RAID hard drives - do they have to be clean?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Gary Dale wrote: On 16/09/14 03:03 PM, Ken Heard wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 One of my boxes has a RAID1 using two Seagate SATA 3.0 1 tb hard drives. I need to replace one of them, and I would like to use as a replacement a Samsung SATA 2.0 1 tb drive which already has on it data which I do not need to keep. My first question is: although both drives are the same size, can I get away with having one drive a Seagate 3.0 and the other Samsung 2.0? snip Any replacement drive has to be large enough to hold the RAID data. If your current RAID1 array is 3T, you cannot add a 2T drive to it without first shrinking the file system then the RAID array. You could however copy all the data to a new RAID1 array consisting of the 2T drive only, then add a 3T drive to it. The new array will again only hold 2T. As it happens all of the drives involved are the same size, 1 tb; so I would not have to deal with the problem you raise. What however is different is the *type* of drive; one is SATA 2.0 and the other is 3.0. Regards, Ken -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAlQZqx4ACgkQlNlJzOkJmTcuxgCdE1PtAQ7IwSQIN+3wfifFBSw5 g8oAn1x3fHhSHJSGABAEsW4p1Z9GW0S+ =dOyA -END PGP SIGNATURE- -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/5419ab1e.4080...@teksavvy.com
Replacement RAID hard drives - do they have to be clean?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 One of my boxes has a RAID1 using two Seagate SATA 3.0 1 tb hard drives. I need to replace one of them, and I would like to use as a replacement a Samsung SATA 2.0 1 tb drive which already has on it data which I do not need to keep. My first question is: although both drives are the same size, can I get away with having one drive a Seagate 3.0 and the other Samsung 2.0? It occurred to me that if I made the change described in the first paragraph -- but without somehow making the data already on it unreadable -- there would be a different data set on each drive; so that the RAID1 software would not necessarily know which drive should be the data source to copy to the other drive. It also occurred to me that the software could combine the data on each drive, so that both drives would have both data sets. I consequently assume that the data on the replacement drive must somehow be made unreadable. Is that assumption correct? If so, do the data have to be shredded, or is it sufficient simply either to delete them or simply reformat the drive? Finally, once I have a clean new drive installed, will the RAID1 copying process partition the new drive the same way as the other drive and copy the files without further human intervention? Regards, Ken Heard -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAlQYiY0ACgkQlNlJzOkJmTc3pQCaA1RHwbzqUChWWwBiqIKYEMXn ascAn27qNBO3OTJUW6NSNAejyPljDzfN =x7+o -END PGP SIGNATURE- -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/5418898d.4050...@teksavvy.com
Re: Replacement RAID hard drives - do they have to be clean?
On 16/09/14 03:03 PM, Ken Heard wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 One of my boxes has a RAID1 using two Seagate SATA 3.0 1 tb hard drives. I need to replace one of them, and I would like to use as a replacement a Samsung SATA 2.0 1 tb drive which already has on it data which I do not need to keep. My first question is: although both drives are the same size, can I get away with having one drive a Seagate 3.0 and the other Samsung 2.0? It occurred to me that if I made the change described in the first paragraph -- but without somehow making the data already on it unreadable -- there would be a different data set on each drive; so that the RAID1 software would not necessarily know which drive should be the data source to copy to the other drive. It also occurred to me that the software could combine the data on each drive, so that both drives would have both data sets. I consequently assume that the data on the replacement drive must somehow be made unreadable. Is that assumption correct? If so, do the data have to be shredded, or is it sufficient simply either to delete them or simply reformat the drive? Finally, once I have a clean new drive installed, will the RAID1 copying process partition the new drive the same way as the other drive and copy the files without further human intervention? Regards, Ken Heard Any replacement drive has to be large enough to hold the RAID data. If your current RAID1 array is 3T, you cannot add a 2T drive to it without first shrinking the file system then the RAID array. You could however copy all the data to a new RAID1 array consisting of the 2T drive only, then add a 3T drive to it. The new array will again only hold 2T. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/54188d8d.6070...@torfree.net
Re: Replacement RAID hard drives - do they have to be clean?
On Tue, 16 Sep 2014 15:03:41 -0400 Ken Heard kensli...@teksavvy.com wrote: My first question is: although both drives are the same size, can I get away with having one drive a Seagate 3.0 and the other Samsung 2.0? Indeed, this is a very recommended configuration, as HDz of the same brand (and much worse: same brans/model/series) have many more chances to break down together. It occurred to me that if I made the change described in the first paragraph -- but without somehow making the data already on it unreadable -- there would be a different data set on each drive; so that the RAID1 software would not necessarily know which drive should be the data source to copy to the other drive. It also occurred to me that the software could combine the data on each drive, so that both drives would have both data sets. That doesn't work like that; first, you have a special block that tells who's who, 2nd, as you'll add the samsung to the array, the system considers that last arrived = new = slave, not master (of data). I consequently assume that the data on the replacement drive must somehow be made unreadable. Is that assumption correct? If so, do the data have to be shredded, or is it sufficient simply either to delete them or simply reformat the drive? That doesn't matter as the software RAID will detect data presence (IF superblocks are at the same place, read: same partition(s) as now), thus, it MAY complain about this data presence and you MIGHT be obliged to force data overwrite on it. Finally, once I have a clean new drive installed, will the RAID1 copying process partition the new drive the same way as the other drive and copy the files without further human intervention? Keep in mind that it can fail for the following reason: HDz aren't exactly the same size (except when same brand, model, series); so if your samsung (partition or full HD, YMMV about raw RAID or not) is even 1 sector less than the ST one, RAID will refuse to reconstruct. More isn't a problem as RAID will only use what it needs. If you reach this point, I strongly suggest making a bit copy (dd) of the working ST HD, then try to shrink it (if the FS allows it, eg: XFS doesn't), then if it succeed, re-add the samsung. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/20140916212213.69c6c6c6@msi.defcon1
Re: Replacement RAID hard drives - do they have to be clean?
On Tue, Sep 16, 2014 at 03:03:41PM -0400, Ken Heard wrote: One of my boxes has a RAID1 using two Seagate SATA 3.0 1 tb hard drives. I need to replace one of them, and I would like to use as a replacement a Samsung SATA 2.0 1 tb drive which already has on it data which I do not need to keep. My first question is: although both drives are the same size, can I get away with having one drive a Seagate 3.0 and the other Samsung 2.0? Yes. I consequently assume that the data on the replacement drive must somehow be made unreadable. Is that assumption correct? If so, do the data have to be shredded, or is it sufficient simply either to delete them or simply reformat the drive? I'm going to assume you're using mdadm. You need to make the new drive have a large partition that is usable as a RAID area. Even if the drive is already a single partition, you will want to change the partition type to fd. Finally, once I have a clean new drive installed, will the RAID1 copying process partition the new drive the same way as the other drive and copy the files without further human intervention? No, you need to partition the new drive and then tell mdadm that it will become part of the RAID. Then everything will be copied across automatically. There is a faq for mdadm. -dsr- -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/20140916191224.gn13...@randomstring.org
