What is RAID0 good for?

My friend has a Win XP PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

On Aug 14, 10:44*am, M.L. wrote:
My friend has a Win XP *PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

RAID 0 is nor really RAID as there is no redundancy. As discovered,
if one drive fails, in effect all data is lost.

The reason for it, in theory it will make the drive run faster. For
the average user, this speed difference may never be seen.

A safer option would be to use JBOD (Just a Bunch Of Disks) and
concatinate the two to make a single 500GB drive.

If a 500GB drive was not required, then 2 x 250GB drives would be a
nice simple solution. This is the option I would choose.

To protect against single disk failure, you require RAID 1. However a
virus problem would still ingect both drives.

To change the setup will require reformating both drives, and so all
current data MUST be backed up first, and then the operating system
etc will need reloading. Probably not worth the effort, just make
sure you have regular backups.

Michael
www.cnwrecover.com

"M.L." wrote:

My friend has a Win XP PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

Just FYI, background on RAID:
http://en.wikipedia.org/wiki/Standard_RAID_levels

*TimDaniels*

M.L. wrote:

My friend has a Win XP PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

RAID does not help against Malware at all. That is not
its purpose. Incidentially RAID-zero has zero RAID
functionality and does indcreae the risk of data-loss, while
it gives some speed improvement.

No, there is not much sense in this configuration for your friend.

Arno

--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email:
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans

On 8/14/2010 5:44 AM, M.L. wrote:

My friend has a Win XP PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

By your description, I think you may be confusing RAID0 with RAID1.
Please let us know whether you are actually talking about RAID 0 or 1?

RAID1 is otherwise known as mirroring. Mirroring is when you have two
exactly identical copies of data in two identical sized hard drives. The
advantage of this is that if one of the two drives dies, the other one
will carry on completely unaffected, and you won't lose any data. The
disadvantage is that your physical drive capacity is halved. Instead of
having 2 x 250GB = 500GB, you only get 250GB.

RAID0 is also known as striping. Striping refers to a performance
enhancement technique where the two drives are added together in such a
way as to interleave disk access. So for example, the first block of
data will reside on disk 1, and the second will be on disk 2, the third
will go back to disk 1, the fourth will go back to disk 2, etc. This
allows the one drive to fetch data even before the previous drive has
finished fetching its data. This allows both drives to remain busy
simultaneously, effectively doubling throughput (though debatable). One
advantage of this is that two 250GB drives will look like one big 500GB
drive. One disadvantage of this is that if one drive fails, the data on
both drives is corrupt, as exactly half of each file is split over two
separate drives, you won't have the full data. Half data is effectively
zero data, as far as you're concerned.

There is a less sophisticated alternative to striping called
concatenation. This is basically just joining one drive to the back of
another drive. This also makes two 250GB drives look like one big 500GB
drive, but instead of interleaving each drive simultaneously, it just
fills up the first drive, and once that's full, it then starts filling
up the second one. Much less sophisticated, but it offers the
possibility that you won't lose all of your files simultaneously. But
even that's debatable, as some file systems may not be able to recover
from the loss of half of their disk space.

Yousuf Khan

In article , " wrote:
On Aug 14, 10:44=A0am, M.L. wrote:
My friend has a Win XP =A0PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

RAID 0 is nor really RAID as there is no redundancy. As discovered,
if one drive fails, in effect all data is lost.

The reason for it, in theory it will make the drive run faster. For
the average user, this speed difference may never be seen.

A safer option would be to use JBOD (Just a Bunch Of Disks) and
concatinate the two to make a single 500GB drive.


How is JBOD "safer" than Raid0 ?

If a 500GB drive was not required, then 2 x 250GB drives would be a
nice simple solution. This is the option I would choose.

To protect against single disk failure, you require RAID 1. However a
virus problem would still ingect both drives.

To change the setup will require reformating both drives, and so all
current data MUST be backed up first, and then the operating system
etc will need reloading. Probably not worth the effort, just make
sure you have regular backups.

Michael
www.cnwrecover.com

GMAN wrote:
In article , " wrote:
On Aug 14, 10:44=A0am, M.L. wrote:
My friend has a Win XP =A0PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

RAID 0 is nor really RAID as there is no redundancy. As discovered,
if one drive fails, in effect all data is lost.

The reason for it, in theory it will make the drive run faster. For
the average user, this speed difference may never be seen.

A safer option would be to use JBOD (Just a Bunch Of Disks) and
concatinate the two to make a single 500GB drive.


How is JBOD "safer" than Raid0 ?

It is, but only by a tiny bit and only with the right
filesystem. The thing is that with RAID0, all data is lost
on a disk failure. With concatenated disks, you may recover
data from the non-failed disk.

Both options are strictly for temporary, low-reliability
storage. Don't use them to hold production data that is
not replicated in other places.

Arno
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email:
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans

On 16/08/2010 05:47, Arno wrote:
wrote:
In , wrote:
On Aug 14, 10:44=A0am, wrote:
My friend has a Win XP =A0PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

RAID 0 is nor really RAID as there is no redundancy. As discovered,
if one drive fails, in effect all data is lost.

The reason for it, in theory it will make the drive run faster. For
the average user, this speed difference may never be seen.

A safer option would be to use JBOD (Just a Bunch Of Disks) and
concatinate the two to make a single 500GB drive.


How is JBOD "safer" than Raid0 ?

It is, but only by a tiny bit and only with the right
filesystem. The thing is that with RAID0, all data is lost
on a disk failure. With concatenated disks, you may recover
data from the non-failed disk.


"JBOD" has two meanings - it can mean "spanning" or "concatenation",
which is what you mean here, or it can mean "treat as several
independent disks".

For spanned disk sets, you have little improvement in safety over Raid0
- files are often scattered around so that you will often have parts on
each disk, and metadata in particular is often spread over the disk
(unless the disk space is very underused - in which case a single disk
is a better choice). In particular, if the first disk is lost then you
will practically speaking lose everything.

Treating the two disks entirely independently is a lot safer, especially
if you copy data across the two disks regularly. So that sort of "JBOD"
is much better than Raid0 (and much safer than Raid1 for typical home
usage).

Both options are strictly for temporary, low-reliability
storage. Don't use them to hold production data that is
not replicated in other places.


Raid is not about data safety - it's about uptime/downtime, and the
convenience of not having to restore from backup when a disk dies. It
doesn't replace backups and data replication.

On 14/08/2010 11:44, M.L. wrote:

My friend has a Win XP PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

Raid0 stripes the two drives for speed and increased capacity, it does
not make any copies.

Raid1 mirrors the drives, so that each holds an exact copy of the other.
This is mainly so that if one of the drives dies, everything carries
on the same. It can also make reads a bit faster, but writes a bit slower.


Redundant raid (raid1 or higher) offer no protection against the likely
causes of problems on a home machine - they only protect against hard
drive failure. While hard drives do occasionally die, the biggest
threats the typical home users' data faces are malware, user error, and
file system corruption. A Raid1 mirror will faithfully replicate all
these faults across the two drives.


So what your friend really needs is a drive for using, and a decent
backup of their data. Given that hardware, the easiest system is to use
one disk as the main disk, and the other as an independent disk for
backups. Keep copies of everything important on both disks, and you
will have a reasonably safe system. It won't protect against the most
vicious of malware that scans the whole system for files to destroy, or
the most stupid of user errors, or the most unlucky of failures (combine
it with copying to CD/DVDs). But it will be a big step forward.

David Brown wrote:
On 16/08/2010 05:47, Arno wrote:
wrote:
In , wrote:
On Aug 14, 10:44=A0am, wrote:
My friend has a Win XP =A0PowerSpec B647 desktop with two 250 GB hard
drives configured in the BIOS as RAID0. It appears that whatever
happens to one drive happens to the other, so when she was infected
with a virus both hard drives were infected, and both were
simultaneously cleaned by the same antivirus scanner.

What good is having those 2 drives perform like that when she is a
non-techie home user who would be better off with the use of 2
independent hard drives? Is there a way to turn off the RAID behavior
so she can get usage more suitable to her needs? Thanks.

RAID 0 is nor really RAID as there is no redundancy. As discovered,
if one drive fails, in effect all data is lost.

The reason for it, in theory it will make the drive run faster. For
the average user, this speed difference may never be seen.

A safer option would be to use JBOD (Just a Bunch Of Disks) and
concatinate the two to make a single 500GB drive.


How is JBOD "safer" than Raid0 ?

It is, but only by a tiny bit and only with the right
filesystem. The thing is that with RAID0, all data is lost
on a disk failure. With concatenated disks, you may recover
data from the non-failed disk.


"JBOD" has two meanings - it can mean "spanning" or "concatenation",
which is what you mean here, or it can mean "treat as several
independent disks".

Actually it typically means either "spanning" or "independent disks
in one storage device". It makes absolutely no sense to call some
independent disks a "JBOD". Not that people have been using that
term for a lot of things. It actually has no defined meaning at all.

For spanned disk sets, you have little improvement in safety over Raid0
- files are often scattered around so that you will often have parts on
each disk, and metadata in particular is often spread over the disk
(unless the disk space is very underused - in which case a single disk
is a better choice). In particular, if the first disk is lost then you
will practically speaking lose everything.

That is why I said "very little", as in "insignificant".

Treating the two disks entirely independently is a lot safer, especially
if you copy data across the two disks regularly. So that sort of "JBOD"
is much better than Raid0 (and much safer than Raid1 for typical home
usage).

Both options are strictly for temporary, low-reliability
storage. Don't use them to hold production data that is
not replicated in other places.


Raid is not about data safety - it's about uptime/downtime, and the
convenience of not having to restore from backup when a disk dies. It
doesn't replace backups and data replication.

I don't agree. RAID (nonzero) does replace replication, it does not
replace backup. It happens to be about data safety, it just
gives you a worse coverage than a backup, so you typically still
need a backup in addition. But if you, for example, do not need
a backup but can do a new installation with fixed, well known
effort, RAID is one way to bring teh failure probability down
enough that a backup becomes cost-ineffective.

Arno
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email:
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans