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Home > Archive > Data Storage > October 2004 > Raid 0 vs Raid 1 - To be or not to be
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Raid 0 vs Raid 1 - To be or not to be
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| BigGuy 2004-10-29, 7:45 am |
| I have just gotten a new system with 2 160GB SATA drives and am trying
to decide which RAID configuration would be best RAID 0 or RAID 1. I
would appreciate any suggestions to make my choice easier.
| |
| Nik Simpson 2004-10-29, 7:45 am |
| BigGuy wrote:
> I have just gotten a new system with 2 160GB SATA drives and am trying
> to decide which RAID configuration would be best RAID 0 or RAID 1. I
> would appreciate any suggestions to make my choice easier.
Are you looking for performance/capacity, or data availability, it's a
binary choice, RAID 0 for the former and RAID 1 for the latter.
--
Nik Simpson
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| BigGuy 2004-10-29, 5:45 pm |
| "Nik Simpson" <n_simpson@bellsouth.net> wrote in message news:<2uetjsF27fsfgU1@uni-berlin.de>...
> BigGuy wrote:
>
> Are you looking for performance/capacity, or data availability, it's a
> binary choice, RAID 0 for the former and RAID 1 for the latter.
Nik:
Thanks. Binary choices are not always easy choices.
I am going from my old system with a 20GB drive up to a new system
with two SATA 160GB droves. I guess that RAID 1 would eliminate the
need to do incremental backups. And if I run out of space I can
always add another drive or two.
| |
| Nik Simpson 2004-10-29, 5:45 pm |
| BigGuy wrote:
> "Nik Simpson" <n_simpson@bellsouth.net> wrote in message
> news:<2uetjsF27fsfgU1@uni-berlin.de>...
>
> Nik:
>
> Thanks. Binary choices are not always easy choices.
> I am going from my old system with a 20GB drive up to a new system
> with two SATA 160GB droves. I guess that RAID 1 would eliminate the
> need to do incremental backups. And if I run out of space I can
> always add another drive or two.
RAID-1 is not a substitute for backups. Yes it protects you from a drive
failure, but it doesn't protect you from the "nut loose at the keyboard"
syndrome. For example, if you accidentally delete an important file, then
it's just as gone as if you only had a single drive.
--
Nik Simpson
| |
| Robert Wessel 2004-10-30, 2:45 am |
| BigBear@columbus.rr.com (BigGuy) wrote in message news:<7a2dce8d.0410291336.32b6605c@posting.google.com>...
> Thanks. Binary choices are not always easy choices.
> I am going from my old system with a 20GB drive up to a new system
> with two SATA 160GB droves. I guess that RAID 1 would eliminate the
> need to do incremental backups. And if I run out of space I can
> always add another drive or two.
Flatly wrong. Mirroring (RAID1) protects you against disk failure
*only*. If you delete a file from a volume on the array, format the
volume, or trash it in some other way (a virus wipes the volume,
whatever), you will have two identical and redundant copies of the now
damaged/destroyed volume.
RAID(!0) has very little impact on the need to do backups. Data loss
is far more common because of some action that damages the data on the
volume than from losing a physical disk. Of course losing a disk (if
there's no redundancy) is pretty catastrophic, and also prevents you
from bringing the system back up until you replace the disk (RAID does
help those, of course). RAID is much more about availability than
backup.
In fact, if you go with RAID0 (striping), you will loose the entire
volume if *either* disk fails, and that might lead you to increase
your backup frequency (again, in most cases the impact on a proper
backup scheme will be negligible).
| |
| Adrian 'Dagurashibanipal' von Bidder 2004-10-30, 7:45 am |
| -----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Clinging to sanity, BigGuy mumbled in his beard:
> I have just gotten a new system with 2 160GB SATA drives and am trying
> to decide which RAID configuration would be best RAID 0 or RAID 1. I
> would appreciate any suggestions to make my choice easier.
This is a really easy choice.
If and only if you require maximal disk performance on data that is
either not important or can be easily regenerated, go with RAID 0
For example, a usenet news server might store its news spool on RAID 0 -
if a disk breaks, just replace and restart the server with an empty
news spool. (IIRC in times before journalled filesystems were common,
administrators even did mkfs instead of fsck on the news spool on boot,
because an INN-style news spool takes ages to fsck - just to illustrate
one of the cases where RAID 0 may make sense)
In all other cases, go with RAID1, or when you can afford to lose the
few hours worth of data between last back up and disk failure and you
can live with the downtime, use tha capacity of the disks fully without
redundancy.
Backup has basically nothing to do with RAID - 99% of the cases where
you'll be restoring files from backup are
- you've been stupid and wiped some files
- your users have been stupid and wiped some files
- you and/or your user have been stupid and/or unlucky, and buggy
software or trojans or hackers have wiped your files.
In none of these cases, RAID does anything for you.
greetings
- -- vbi
- --
Beware of the FUD - know your enemies. This week
* The Alexis de Toqueville Institue *
http://fortytwo.ch/opinion/
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| |
| BigGuy 2004-10-31, 7:45 am |
| Adrian 'Dagurashibanipal' von Bidder <grazdan@fortytwo.ch> wrote in message news:<9563119.fYHDTP1yls@altfrangg.fortytwo.ch>...
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Clinging to sanity, BigGuy mumbled in his beard:
>
>
> This is a really easy choice.
>
> If and only if you require maximal disk performance on data that is
> either not important or can be easily regenerated, go with RAID 0
>
> For example, a usenet news server might store its news spool on RAID 0 -
> if a disk breaks, just replace and restart the server with an empty
> news spool. (IIRC in times before journalled filesystems were common,
> administrators even did mkfs instead of fsck on the news spool on boot,
> because an INN-style news spool takes ages to fsck - just to illustrate
> one of the cases where RAID 0 may make sense)
>
> In all other cases, go with RAID1, or when you can afford to lose the
> few hours worth of data between last back up and disk failure and you
> can live with the downtime, use tha capacity of the disks fully without
> redundancy.
>
>
> Backup has basically nothing to do with RAID - 99% of the cases where
> you'll be restoring files from backup are
>
> - you've been stupid and wiped some files
> - your users have been stupid and wiped some files
> - you and/or your user have been stupid and/or unlucky, and buggy
> software or trojans or hackers have wiped your files.
>
> In none of these cases, RAID does anything for you.
>
>
> greetings
> - -- vbi
>
> - --
> Beware of the FUD - know your enemies. This week
> * The Alexis de Toqueville Institue *
> http://fortytwo.ch/opinion/
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.2.4 (GNU/Linux)
> Comment: get my key from http://fortytwo.ch/gpg/92082481
>
> iKcEARECAGcFAkGDlBxgGmh0dHA6Ly9mb3J0eXR3
by5jaC9sZWdhbC9ncGcvZW1h
> aWwuMjAwMjA4MjI/ dmVyc2lvbj0xLjUmbWQ1c3VtPTVkZmY4NjhkMTE4
NDMyNzYw
> NzFiMjVlYjcwMDZkYTNlAAoJEIukMYvlp/fWB0kAn3h3iwHkxOhC+oY/VEiKAr75
> zjwxAKCzYRz/K9SFOZ9NSQu1sPIRUUFAlA==
> =KAnK
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Thanks Adrian:
Now I get it. Or should I say will get it - one more drive just for
backups. Then, in RAID 1, with the additional Hard drive, I will have
a stable working system - lots of storage, easy backup. Whew! I
thought I would never get it straight.
BigGuy
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