Re: [opensuse] Of software RAID on SUSE Linux
On Sunday 30 November 2008, you wrote:
On Thu, Nov 27, 2008 at 5:50 PM, Tero Pesonen <mlist-suse@tpesonen.net> wrote:
Of course, a RAID won't help against other kinds of data loss, such as the power supply's failing and killing other components with some mighty spike; or from fire, or flood, or what ever. That is OK. That's why I backup.
Are you using a UPS?
I've never used a UPS device before for a desktop at home. I've been thinking of acquiring one for the new system -- the one with the RAID -- so as to avoid problems in case of a black-out. I've read that this is recommended with RAIDs as the disks need to keep in sync and no-one knows what'll happen when they all power down unexpectedly. So having the system go down gracefully is preferred. I have not yet looked at products or prices. But if I had a UPS for my home box, and the power went out, and the UPS went to work for a short period of time, how would my system know to "init 0" or something like that during the time the UPS would be able to feed it? Do you have one, and if so, how does your setup work?
In other words, may I combine disks from different manufacturers, with different specs, etc. without affecting the RAID somehow negatively?
It is OK to mix manufacturers and capacities. It is good to mix discs with different manufacture dates. This makes it less likely that the discs will fail at the same time. But I would not mix buses, spindle speed or cache size because I would not want to thrash one disc while leaving the other one idle.
OK.
So, while you can mix discs, I bought an identical pair of hard discs for my RAID 1. Using a pair of identical discs takes the guesswork out of building a RAID. And I am satisfied with the result.
I guess two might suffice for me, too. Two identical Seagate ES.2 SATA's might work. They're specsed by the manufacturer for 24h use, for whatever that is worth (I always run my desktop 24h/d, and keep KDE up for months at time... so the disks spin a good deal. This is mostly because the OS-disks cannot be spinned down with hdparm for more than a few seconds due to the kernel's constantly flushing them. So, at night they are merely idling away at 7200rpm.) I prefer not to turn the power on and off too much, as doing so seems the most efficient way for killing modern-day crappy PC components. Keeping the thing running seems to provide the most stable system. I've only experienced one power cut on my home box over the past 10 years. Luckily, that did not cause any fs errors, and reiserfs recovered from it with a boot-time fsck (that did quite a bit of work, though) without leaving any problems even though the disk had been writing when the power was cut.
On the other hand, replacing disks later with larger capacity ones will cause no problem as they only need to meet the minimum size criterion. Hence, I could replace them one-by-one such that each new disk, replacing a removed old one, is first let to fully integrate/reconstruct; finally, after all disk have been replaced, I could enlarge a partition or two, for example, as allowed by the new shared minimum, thus increasing the capacity of the virtual device that is being RAIDed.
Remember to back up before experimenting.
Of course. Thanks to my rigorous habit of backing-up, despite hard drive failures, I have never really lost any important data.
You might want to look at using LVM rather than expanding partitions.
I'll do that. Thanks for the tip!
My System
I have a three disc system. I have one disc for the OS. And I have a matched pair of Seagates in a RAID 1. The OS disc is a throwaway disc. In other words, if something happens to it, I can just buy a new disc, build a new install of openSuSE and be on my way. I have no personal data on that disc. All of my data is on the RAID 1. And I have a separate mount point for my stuff that does not overlap with any standard Linux mount point such as /home or whatever. So the biggest risks to my data are a double hardware failure or operator error.
That seems like a good strategy. I will have to consider that kind of approach too.
I also have a removable hard drive with the same capacity as my RAID that I use for backing up.
Mike
Thanks for your comments! Tero Pesonen -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sunday, 2008-11-30 at 22:23 +0200, Tero Pesonen wrote:
But if I had a UPS for my home box, and the power went out, and the UPS went to work for a short period of time, how would my system know to "init 0" or something like that during the time the UPS would be able to feed it?
First, you need one that has some time of communication port with the computer. The old type just had some contacts, that were plugged into some of the auxiliary control lines of a serial port, and this way, the status of "online, on batt, or batt nearly depleted" can be communicated to the computer. Then, there are better types with an ethernet, usb port, or real serial port, and contain some kind of microprocessor. And some of them can be controlled by linux, using the package "nut", or sometimes, a proprietary package of the maker. Bad news is that they can cost almost double the price of a plain UPS. - -- Cheers, Carlos E. R. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iEYEARECAAYFAkkzArQACgkQtTMYHG2NR9WEqQCfVcWf5l4aIAvkFhNgU4hh0eBU 4jsAnR2/30o7kTGzLdr18QxNaVrSECoy =3h4D -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Carlos E. R. wrote:
On Sunday, 2008-11-30 at 22:23 +0200, Tero Pesonen wrote:
But if I had a UPS for my home box, and the power went out, and the UPS went to work for a short period of time, how would my system know to "init 0" or something like that during the time the UPS would be able to feed it?
First, you need one that has some time of communication port with the computer.
The old type just had some contacts, that were plugged into some of the auxiliary control lines of a serial port, and this way, the status of "online, on batt, or batt nearly depleted" can be communicated to the computer. Then, there are better types with an ethernet, usb port, or real serial port, and contain some kind of microprocessor.
And some of them can be controlled by linux, using the package "nut", or sometimes, a proprietary package of the maker. Bad news is that they can cost almost double the price of a plain UPS.
I have a couple, made by APC that work well. They're connected by USP and managed by apcupsd, which is included with OpenSUSE. They are inexpensive and available in many computer and office supply stores. -- Use OpenOffice.org <http://www.openoffice.org> -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Sun, Nov 30, 2008 at 3:23 PM, James Knott <james.knott@rogers.com> wrote:
Carlos E. R. wrote:
On Sunday, 2008-11-30 at 22:23 +0200, Tero Pesonen wrote:
But if I had a UPS for my home box, and the power went out, and the UPS went to work for a short period of time, how would my system know to "init 0" or something like that during the time the UPS would be able to feed it?
First, you need one that has some time of communication port with the computer.
The old type just had some contacts, that were plugged into some of the auxiliary control lines of a serial port, and this way, the status of "online, on batt, or batt nearly depleted" can be communicated to the computer. Then, there are better types with an ethernet, usb port, or real serial port, and contain some kind of microprocessor.
And some of them can be controlled by linux, using the package "nut", or sometimes, a proprietary package of the maker. Bad news is that they can cost almost double the price of a plain UPS.
I have a couple, made by APC that work well. They're connected by US[B] and managed by apcupsd, which is included with OpenSUSE. They are inexpensive and available in many computer and office supply stores.
I contacted APC a while back to get my Back-UPS XS 1500 working with PowerChute-like soft shutdowns. But I gave up on it since I never used it that much. My computer is usually off. The techs at APC were pretty helpful. But they did not tell me anything I did not already know. apcupsd is really the place to get started. Come to think of it, I'm not even sure I could communicate with my UPS. I remember there being some disagreement whether my USB-to-RJ-45 cable would work or not. Maybe the apcupsd project could shed more light on compatibility. Sorry I can't be of more help. Supported UPSes and Cables http://www.apcupsd.org/manual/Supported_UPSes_Cables.html Mike -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Sunday 30 November 2008, James Knott wrote:
Carlos E. R. wrote:
On Sunday, 2008-11-30 at 22:23 +0200, Tero Pesonen wrote:
But if I had a UPS for my home box, and the power went out, and the UPS went to work for a short period of time, how would my system know to "init 0" or something like that during the time the UPS would be able to feed it?
First, you need one that has some time of communication port with the computer.
The old type just had some contacts, that were plugged into some of the auxiliary control lines of a serial port, and this way, the status of "online, on batt, or batt nearly depleted" can be communicated to the computer. Then, there are better types with an ethernet, usb port, or real serial port, and contain some kind of microprocessor.
And some of them can be controlled by linux, using the package "nut", or sometimes, a proprietary package of the maker. Bad news is that they can cost almost double the price of a plain UPS.
I have a couple, made by APC that work well. They're connected by USP and managed by apcupsd, which is included with OpenSUSE. They are inexpensive and available in many computer and office supply stores.
OK. APC seems to be well represented in pretty much everywhere. I'll take a look at what they have to offer. Thanks, Tero Pesonen -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Monday, 2008-12-01 at 17:52 +0200, Tero Pesonen wrote:
OK. APC seems to be well represented in pretty much everywhere. I'll take a look at what they have to offer.
You are not limited to apc; I have a belkin, and it works well with nut. - -- Cheers, Carlos E. R. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iEYEARECAAYFAkk0DLYACgkQtTMYHG2NR9VEjwCghLju32eZsqwFUcfwxLpBEMkf BHsAn1IaAP4WAXgSoSWesghmlAxtSuz2 =3UyU -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On 01 December 08, Carlos E. R. wrote:
On Monday, 2008-12-01 at 17:52 +0200, Tero Pesonen wrote:
OK. APC seems to be well represented in pretty much everywhere. I'll take a look at what they have to offer.
You are not limited to apc; I have a belkin, and it works well with nut.
Problem is, neither apcupsd nor nut are very easy to setup. As a matter of fact, they're simply a PITA and most 'average' users give up after just a few minutes of trying. It's unfortunate, because if one has an UPS and isn't nearby to turn the machine off when the power goes out, the battery gets used up lots faster (meaning it won't last nearly as long as if it could be automatically shutdown in a minute or less with the software). :( -- The Second Amendment is in place in case the politicians ignore the others. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Monday, 2008-12-01 at 22:28 -0600, JB2 wrote:
Problem is, neither apcupsd nor nut are very easy to setup. As a matter of fact, they're simply a PITA and most 'average' users give up after just a few minutes of trying. It's unfortunate, because if one has an UPS and isn't nearby to turn the machine off when the power goes out, the battery gets used up lots faster (meaning it won't last nearly as long as if it could be automatically shutdown in a minute or less with the software). :(
You are absolutely right, I had to fight it over with nut for some days. I won. Part of the battle has been registered here, in this mail list ;-) I opened several bugzillas about the problems I found, and I still have in my to-do list checking of the proposed changes in one of the bugzillas. Actually, nut wold have worked almost out of the box if a certain change is applied to the configuration. The problem is knowing which change... and only for one model. The list of hardware and drivers they have is not very helpful in this respect. But the way, nut doesn't power off immediately, but it waits till the UPS unit reports itself as nearly depleted. This is not configurable, as far as I could see. However, you can define your own rules to power off by time, but this is not trivial. I have set mine to suspend to disk (not 'halt') after two minutes. The developers think that it is better to use the battery till almost no charge remain, in the hope that electricity returns in time. I think different, because power problems can repeat themselves, and, at least in my case, the battery takes 8 hours to recharge: time enough for another outage. - -- Cheers, Carlos E. R. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iEYEARECAAYFAkk1ZCwACgkQtTMYHG2NR9UczACgmWDBhLnq9AksqNFYEpcJijLt aCcAn1wEpkHAQaR19I4FYtb6TlYPMk7F =WZPi -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
participants (5)
-
Carlos E. R. -
James Knott -
JB2 -
Michael Mientus -
Tero Pesonen