hi ya
On Sat, 8 Mar 2003, Juhan Kundla wrote:
>
> I have a task to set up a file server. I have very small budget but
> quite high demands for data integrity. I must do everything possible to
> ensure, that i can recover data after hardware or user failures.
> The performance of the computer is not very important.
does "data integrity" means that the server cannot go down or that
you cannot lose data, even if the server is offline for a day or two
if the server cannot go down, you will need to be using mirroring (raid1
or raid5 )
if you just want to be able to recover data ( not lose a single file ) ...
- implement a "good" backup scheme ..
- you will have restrictions, can people afford to lose a days
work ?? ( if not, run backups during the workday too )
- you wil lose data, unless you have saved multiple copies of
it at the time the file was created ...
- paranoid way to prevent data loss, write the "transaction"
to your servers in SF, LA, NYC, Chicago
> There is no way i could buy expensive hardware (SCSI and tape drives are
> really not an option). I think i can afford two or three IDE disks. So
> here is my plan.
if data reliability is important... i would NOT use scsi..
( all my dead drives are scsi drivers ( runns too hot )
( all my bad ide disks are ibm deskstars ...
> I buy two smaller (and cheaper) IDE disks and use them in RAID-1 array.
> I hope that this gives me good protection against hardware failures. If
> one disk fails, then other will still have my data intact, right? The
> main question is, that how good is the software RAID, when one drive is
> not lost completely, but it starts to have more and more bad blocks?
> Will the RAID-1 protect me from data corruption in that case? Any
> comments?
good... for knowing backups is needed
> I know, i still have to take backups, because the RAID and mirroring
> won't protect me against other types of failures. I was thinking about
> using a separate much bigger IDE disk for backups. If the backup drive
> would be 7 times bigger than those smaller disks, then i could take a
> full backup every weekday and have seven copies of my data, every copy
> taken in different time. This gives me maximum one week to react to data
> loss or corruption and if i accidently deleted wrong files, i would
> could restore them from backup, that is not older than 24 hours.
given disk space is limited .. and limited budgets ...
a. you should only backup data from last full backup that was performed
- if you're paranoid, since 2 full-backups ago
- if you do weekly full backups, than do daily incremental backups
of the last 22 days...
-- assume that your full backups will fail regularly...
- backup disk will be too full
- network will be down regularly... for whatever reason
which renders your daily incrementals worthless unless you
can recover the missing day's worth of incremental backups
-- a missing day or missing file due to poor full backups or poor daily
incremental backup scheme renders all subsequent incremental backups
useless
- make sure incremental backups are performed across several
full backups ( how ever often you do full backups )
-- only backup user data .... and server config ...
( no point to backup system files like /usr/X11R6 for example )
-- if your main data disk is 40GB ...
- a 2nd 40GB disk will give you about a months worth of backups
( depending on if you have 40GB of ascii docs or 40GB of mpegfiles )
- a 3rd 40GB disk is good .. just in case a backup failed
-- test the backups is working on a regular basis...
-- insert a test file ...
-- some time next week seethat when a fresh disk is restored,
that your "test files" exists
backup scripts
http://wwww.Linux-Backup.net
raid stuff
http://www.1U-Raid5.net
c ya
alvin
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