Re: [gentoo-user] {OT} Why RAID1?
Stroller schrieb: On 17 Dec 2008, at 10:25, KH wrote: ... Also there have been articles that if one drive of a raid dies there is a chance that you cannot recover your data. This is based on the theory, that one of the other drives have hidden errors. The chances for this grow with the size of the hd. [Citation Needed] http://hardware.slashdot.org/article.pl?sid=08/10/21/2126252from=rss http://blogs.zdnet.com/storage/?p=162 kh
Re: [gentoo-user] {OT} Why RAID1?
Volker Armin Hemmann schrieb: On Mittwoch 17 Dezember 2008, Stroller wrote: On 17 Dec 2008, at 10:25, KH wrote: ... Also there have been articles that if one drive of a raid dies there is a chance that you cannot recover your data. This is based on the theory, that one of the other drives have hidden errors. The chances for this grow with the size of the hd. [Citation Needed] gentoo wiki and gentoo documentation. That is why you should check your raid regularly for errors. I do that but I also had problem with my raid when there have not been any errors. # echo check /sys/block/md1/md/sync_action Well someone once said: There are two kinds of people: Those who never had a disk failure and those who have backups. kh
Re: [gentoo-user] {OT} Why RAID1?
Iain Buchanan schrieb: On 17/12/08 19:57, KH wrote: Neil Bothwick schrieb: On Wed, 17 Dec 2008 11:18:24 +0100, KH wrote: Which is why you still need offsite backups. Best you have them with your grandparents in another town. Maybe there is a flood ;-) Mine are a thousand miles away, so unless its another Biblical flood... That scares me. Mine are only 60 miles away. Maybe I should search a friend in Australia ... no good. We're expecting a cyclone up north, and down south they're so dry it'll probably catch fire... Lets go for sure: http://rss.slashdot.org/~r/Slashdot/slashdotHardware/~3/FxV7Am-GaYk/article.pl I think there is another one in the swiss alps ... kh
Re: [gentoo-user] {OT} Why RAID1?
On 18 Dec 2008, at 11:44, KH wrote: Stroller schrieb: On 17 Dec 2008, at 10:25, KH wrote: ... Also there have been articles that if one drive of a raid dies there is a chance that you cannot recover your data. This is based on the theory, that one of the other drives have hidden errors. The chances for this grow with the size of the hd. [Citation Needed] http://hardware.slashdot.org/article.pl?sid=08/10/21/2126252from=rss http://blogs.zdnet.com/storage/?p=162 That article is bollocks, and widely debunked. Stroller.
Re: [gentoo-user] {OT} Why RAID1?
Stroller schrieb: On 18 Dec 2008, at 11:44, KH wrote: Stroller schrieb: On 17 Dec 2008, at 10:25, KH wrote: ... Also there have been articles that if one drive of a raid dies there is a chance that you cannot recover your data. This is based on the theory, that one of the other drives have hidden errors. The chances for this grow with the size of the hd. [Citation Needed] http://hardware.slashdot.org/article.pl?sid=08/10/21/2126252from=rss http://blogs.zdnet.com/storage/?p=162 That article is bollocks, and widely debunked. Stroller. [Citation Needed] ;-) kh
Re: [gentoo-user] {OT} Why RAID1?
On Tue, 16 Dec 2008 18:24:27 -0800, Grant wrote: I'm about to buy a couple Samsung Spinpoint F1 hard drives and I was planning on setting them up in a RAID0 array. Everyone seems to love RAID1 though, and I'm a little confused as to why. Don't daily backups secure 99% of the data that RAID1 does? No. If you backup runs in the early hours on a cron script and your drive fails at 6pm, not only have you lost a full day's work, but you'll spend the rest of the evening restoring your backups to a new drive. The next day you'll be tired and bleary-eyed, and still a day behind. With RAID1 (or 5), you just plug in another drive. RAID should not be considered an alternative to backups, but a separate layer of data security. They even protect in the event of theft or fire which RAID1 doesn't. Which is why you still need offsite backups. -- Neil Bothwick A closed mouth gathers no foot. signature.asc Description: PGP signature
Re: [gentoo-user] {OT} Why RAID1?
On Wed, 17 Dec 2008 11:18:24 +0100, KH wrote: Which is why you still need offsite backups. Best you have them with your grandparents in another town. Maybe there is a flood ;-) Mine are a thousand miles away, so unless its another Biblical flood... -- Neil Bothwick Earlier, I didn't have time to finish anything. This time I w signature.asc Description: PGP signature
Re: [gentoo-user] {OT} Why RAID1?
I'm about to buy a couple Samsung Spinpoint F1 hard drives and I was planning on setting them up in a RAID0 array. Everyone seems to love RAID1 though, and I'm a little confused as to why. Don't daily backups secure 99% of the data that RAID1 does? They even protect in the event of theft or fire which RAID1 doesn't. If one hard drive dies in a RAID1 array, does the system keep running? If so, that's good, but there are so many other components that could die. In 15 years I've lost the power supply, video card, modem, motherboard, and CPU, but never a hard drive. With all these potential points of failure, how much greater system reliability do mirrored hard drives really offer? In fifteen years I've lost roughly fifteen hard drives and one power supply. Hard drives have moving parts and that equals failures. Congratulations on being lucky, though you have wonder why so many thing that don't normally have issues are having issues in your system. :-) Do you guys think RAID1 is unnecessary with an SLC SSD drive? I actually did lose one or two laptop hard drives now that I think about it. The other stuff: power supply - cheapness video cards - heat modem - lightning motherboard and CPU - overclocking (never again) - Grant
Re: [gentoo-user] {OT} Why RAID1?
Neil Bothwick schrieb: On Tue, 16 Dec 2008 18:24:27 -0800, Grant wrote: They even protect in the event of theft or fire which RAID1 doesn't. Which is why you still need offsite backups. Best you have them with your grandparents in another town. Maybe there is a flood ;-) kh
Re: [gentoo-user] {OT} Why RAID1?
Grant wrote: Do you guys think RAID1 is unnecessary with an SLC SSD drive? No need for RAID1, brand new technology always works right in the first generation. There are never problems. :-D It would be interesting to run RAID1 between an SSD and SATA drive. I wonder what sort of issues the disparity in speed would cause. kashani
Re: [gentoo-user] {OT} Why RAID1?
Do you guys think RAID1 is unnecessary with an SLC SSD drive? No need for RAID1, brand new technology always works right in the first generation. There are never problems. :-D It would be interesting to run RAID1 between an SSD and SATA drive. I wonder what sort of issues the disparity in speed would cause. I thought the drives had to be identical. - Grant
Re: [gentoo-user] {OT} Why RAID1?
On Mittwoch 17 Dezember 2008, Grant wrote: I'm about to buy a couple Samsung Spinpoint F1 hard drives and I was planning on setting them up in a RAID0 array. Everyone seems to love RAID1 though, and I'm a little confused as to why. Don't daily backups secure 99% of the data that RAID1 does? They even protect in the event of theft or fire which RAID1 doesn't. raid does not replace backups. If one hard drive dies in a RAID1 array, does the system keep running? yes, and that is whay raid1 (with two disks) is a good idea. If so, that's good, but there are so many other components that could die. In 15 years I've lost the power supply, video card, modem, motherboard, and CPU, but never a hard drive. With all these potential points of failure, how much greater system reliability do mirrored hard drives really offer? I had a PSU killing two mobos - and I had half a douzend harddisk failures in 12 PC years. Everything else never died. Even the PSUs going bad did it so slowly that there was enough of time to get a replacement. Harddisks sucks - Raid1,5,6 make the sucking less painfull.
Re: [gentoo-user] {OT} Why RAID1?
Neil Bothwick schrieb: On Wed, 17 Dec 2008 11:18:24 +0100, KH wrote: Which is why you still need offsite backups. Best you have them with your grandparents in another town. Maybe there is a flood ;-) Mine are a thousand miles away, so unless its another Biblical flood... That scares me. Mine are only 60 miles away. Maybe I should search a friend in Australia ...
Re: [gentoo-user] {OT} Why RAID1?
On Wed, 2008-12-17 at 12:51 -0800, Grant wrote: Do you guys think RAID1 is unnecessary with an SLC SSD drive? No need for RAID1, brand new technology always works right in the first generation. There are never problems. :-D It would be interesting to run RAID1 between an SSD and SATA drive. I wonder what sort of issues the disparity in speed would cause. I thought the drives had to be identical. No, the only real requirement is that they both be (virtual) block devices. It's just that the maximum array size for RAID1 will be the size of the smaller drive.
Re: [gentoo-user] {OT} Why RAID1?
Grant schrieb: I'm about to buy a couple Samsung Spinpoint F1 hard drives and I was planning on setting them up in a RAID0 array. Everyone seems to love RAID1 though, and I'm a little confused as to why. Don't daily backups secure 99% of the data that RAID1 does? They even protect in the event of theft or fire which RAID1 doesn't. If one hard drive dies in a RAID1 array, does the system keep running? If so, that's good, but there are so many other components that could die. In 15 years I've lost the power supply, video card, modem, motherboard, and CPU, but never a hard drive. With all these potential points of failure, how much greater system reliability do mirrored hard drives really offer? - Grant I also had a lot of hard drives die (like 7 by now). Also I have a lot of not to use anymore backup CDs and DVDs. They become old and that isn't to good for them. One should backup a CD/DVD every year or so (don't trust the this dvd is golden and will be there in 100 years. I am extremely sure they did't test it, yet ;-) ) Also there have been articles that if one drive of a raid dies there is a chance that you cannot recover your data. This is based on the theory, that one of the other drives have hidden errors. The chances for this grow with the size of the hd. kh
Re: [gentoo-user] {OT} Why RAID1?
On Wed, 2008-12-17 at 12:30 -0800, kashani wrote: Grant wrote: Do you guys think RAID1 is unnecessary with an SLC SSD drive? No need for RAID1, brand new technology always works right in the first generation. There are never problems. :-D It would be interesting to run RAID1 between an SSD and SATA drive. I wonder what sort of issues the disparity in speed would cause. WRT writes it will pretty much nullify the advantage of having the SSD since all writes will be the speed of the slowest drive (the SATA). A write request is not completed until all mirrors are written to. You likely will have a slower reads as well since nearly half the time the reads are coming from the much slower SATA drive (i.e. the time you'll be waiting on the seeks/reads on the SATA will be much longer than all the reads on the SDD).
Re: [gentoo-user] {OT} Why RAID1?
On 17 Dec 2008, at 02:24, Grant wrote: ... Everyone seems to love RAID1 though, and I'm a little confused as to why. Everyone loves RAID1 because it backs up your data. Note the use of quotation marks. You stated that data throughput was a bottleneck for your system, so RAID1 may not give you the benefits you require. Under RAID0 any given byte is read or written 1/2 from drive A 1/2 from drive B. Under RAID1 any given byte may be read or 1/2 from drive A 1/2 from drive B, but must be written completely to both drives. Compared to a single drive: RAID1 doubles sustained read speed (write speed unaffected). RAID0 doubles sustained read AND write speeds. Stroller.
Re: [gentoo-user] {OT} Why RAID1?
On 17 Dec 2008, at 10:25, KH wrote: ... Also there have been articles that if one drive of a raid dies there is a chance that you cannot recover your data. This is based on the theory, that one of the other drives have hidden errors. The chances for this grow with the size of the hd. [Citation Needed]
Re: [gentoo-user] {OT} Why RAID1?
On Mittwoch 17 Dezember 2008, Stroller wrote: On 17 Dec 2008, at 10:25, KH wrote: ... Also there have been articles that if one drive of a raid dies there is a chance that you cannot recover your data. This is based on the theory, that one of the other drives have hidden errors. The chances for this grow with the size of the hd. [Citation Needed] gentoo wiki and gentoo documentation. That is why you should check your raid regularly for errors.
Re: [gentoo-user] {OT} Why RAID1?
On Mittwoch 17 Dezember 2008, Albert Hopkins wrote: On Wed, 2008-12-17 at 12:30 -0800, kashani wrote: Grant wrote: Do you guys think RAID1 is unnecessary with an SLC SSD drive? No need for RAID1, brand new technology always works right in the first generation. There are never problems. :-D It would be interesting to run RAID1 between an SSD and SATA drive. I wonder what sort of issues the disparity in speed would cause. WRT writes it will pretty much nullify the advantage of having the SSD since all writes will be the speed of the slowest drive (the SATA). A write request is not completed until all mirrors are written to. and I am not sure that the SSD is the fast writer ...
Re: [gentoo-user] {OT} Why RAID1?
On 17/12/08 19:57, KH wrote: Neil Bothwick schrieb: On Wed, 17 Dec 2008 11:18:24 +0100, KH wrote: Which is why you still need offsite backups. Best you have them with your grandparents in another town. Maybe there is a flood ;-) Mine are a thousand miles away, so unless its another Biblical flood... That scares me. Mine are only 60 miles away. Maybe I should search a friend in Australia ... no good. We're expecting a cyclone up north, and down south they're so dry it'll probably catch fire... -- Iain Buchanan iaindb at netspace dot net dot au Dr. Jekyll had something to Hyde.
[gentoo-user] {OT} Why RAID1?
I'm about to buy a couple Samsung Spinpoint F1 hard drives and I was planning on setting them up in a RAID0 array. Everyone seems to love RAID1 though, and I'm a little confused as to why. Don't daily backups secure 99% of the data that RAID1 does? They even protect in the event of theft or fire which RAID1 doesn't. If one hard drive dies in a RAID1 array, does the system keep running? If so, that's good, but there are so many other components that could die. In 15 years I've lost the power supply, video card, modem, motherboard, and CPU, but never a hard drive. With all these potential points of failure, how much greater system reliability do mirrored hard drives really offer? - Grant
Re: [gentoo-user] {OT} Why RAID1?
Grant wrote: I'm about to buy a couple Samsung Spinpoint F1 hard drives and I was planning on setting them up in a RAID0 array. Everyone seems to love RAID1 though, and I'm a little confused as to why. Don't daily backups secure 99% of the data that RAID1 does? They even protect in the event of theft or fire which RAID1 doesn't. If one hard drive dies in a RAID1 array, does the system keep running? If so, that's good, but there are so many other components that could die. In 15 years I've lost the power supply, video card, modem, motherboard, and CPU, but never a hard drive. With all these potential points of failure, how much greater system reliability do mirrored hard drives really offer? In fifteen years I've lost roughly fifteen hard drives and one power supply. Hard drives have moving parts and that equals failures. Congratulations on being lucky, though you have wonder why so many thing that don't normally have issues are having issues in your system. :-) Do I back my stuff up? Yes. Do I also run RAID1? Yes. Why? Because having to go dig you backup out is really time consuming whereas ordering a new hard drive and plugging it in requires next to no work. In almost all cases I can think of your RAID1 system will continue to keep running with the lost of a single disk. Also RAID1 acts like RAID0 when you're reading from it so there is a performance increase on reads. kashani
Re: [gentoo-user] {OT} Why RAID1?
Get the best of both worlds with raid 5. Personally, I do raid 0 and I agree with you on raid redundancy not being very useful. Backup ftw. I cycle out my hard drives every year or two and make the old ones be backups, I've only ever had the backups die. - Ian
Re: [gentoo-user] {OT} Why RAID1?
On Tue, Dec 16, 2008 at 7:45 PM, smallnow small...@gmail.com wrote: Get the best of both worlds with raid 5. Personally, I do raid 0 and I agree with you on raid redundancy not being very useful. Backup ftw. I cycle out my hard drives every year or two and make the old ones be backups, I've only ever had the backups die. - Ian Hmm. I grew up with very expensive hard drives, and never thought of this. Time to rethink. My first Unix hard drive replacement was a 20MB drive replacing 10MB and it cost $600 (1985 dollars) plus the old drive. Circa 1985. You didn't do that too often on a home system. Now that I'm seeing 1,000,000 MB eSATAs for under $100 this is starting to make sense. Thanks for the idea. ++ kevin -- Kevin O'Gorman, PhD
