Re: ZFS with Linux: An Open Plea

On Mon, Apr 16, 2007 at 10:18:45PM +0200, Tomasz K?oczko wrote:
Of cources it can be true in most cases (probably for some more advanced
RAID controlers). Few weeks ago I perform some basic test on Dell 2950
with 8x73GB SAS disk .. just as for kill time (waiting for access to some
bigger box ;). This small iron box have inside RAID controller (Dell uses
in this box LSI Logic SAS MegaRAID based ctrl). Anykind combinations on
controler level RAID was slower than using this as plain JBOD with LVM or
MD+LVM. Diffrence between HW and soft RAID was not so big (1-6% depending
on configuration) but allways HW produces worser results (don't ask me
why). Finaly I decide using this disk as four RAID1 luns only because
under Linux I can't read each phisical disk SMART data and protecting this
by RAID on controller level and collecting SNMP traps from DRAC card was
kind of worakaround for this (in my case it will be better constanlty
monitor disk healt and collesting some SMART data for observe trends on
for example zabbix graphs for try predict some faults using triggers). On
top of this was configured diffrent types of volumes on LVM level (some
with stripping some without, some with bigger some with smaller chunk
size).

Does it matter that google's recent report on disk failures indicated
that SMART never predicted anything useful as far as they could tell?
Certainly none of my drive failures ever had SMART make any kind of
indication that anything was wrong.

I think the main benefit of MD raid, is that it is portable, doesn't
lock you into a specific piece of hardware, and you can span multiple
controllers, and it is likely easier to have bugs in MD raid fixed that
in some raid controller's firmware if any were to be found. Performance
advantages are a bonus of course.

--
Len Sorensen
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Relevant Pages

  • Re: Platzierung und Größe der Auslagerungsdatei
    ... der Controller steckt, ... Bei der Latency ist die Raptor um Faktor 1,4, bei der Seektime um Faktor ... We recommend that you plan to use less than 80% disk utilization at ... Raid 0 has the same cost as no raid. ...
    (microsoft.public.de.german.windows.server.general)
  • Re: Have you booted from SRC/P RAID?
    ... You're thinking of a completey different kind of RAID configuration. ... The SRC/P is a SCSI-RAID controller card that inserts into a PCI slot ... whether it's a physical disk or a logical disk, ...
    (comp.unix.solaris)
  • Re: Installing Adaptec 1420SA SATA RAID controller
    ... neither disk nor RAID array. ... What about returning the Adaptec controller and replacing it with some ...
    (microsoft.public.windows.server.sbs)
  • Re: New SATA hard drive not being detected
    ... powering on the PC (or doing a warm boot). ... Another possible problem is that the SATA controller may also be a RAID ... partition and format the disk. ...
    (microsoft.public.windowsxp.help_and_support)
  • Re: SBS 2003 Program Files Partition
    ... Well if you only have one RAID Controller then you can only use one RAID ... > When I was talking about different partitions I had in mind that you would ... > have less trouble with disk fragmentation (since the most write accesses ...
    (microsoft.public.windows.server.sbs)