From mboxrd@z Thu Jan 1 00:00:00 1970 From: SandeepKsinha Subject: Re: RAID4 and RAID5 Code Date: Sat, 16 May 2009 10:02:05 +0530 Message-ID: <37d33d830905152132w4abe803bk2c066d90fbf4ce8e@mail.gmail.com> References: <37d33d830905140957q6e180d89v4cd4a21d23471481@mail.gmail.com> <4A0D9384.1020805@zytor.com> <37d33d830905150914v5d780e44s6cc2174944530ddb@mail.gmail.com> <4A0DB688.7050301@harddata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <4A0DB688.7050301@harddata.com> Sender: linux-raid-owner@vger.kernel.org To: Maurice Hilarius Cc: hpa@zytor.com, vger majordomo for lists , linux-raid-owner@vger.kernel.org List-Id: linux-raid.ids On Sat, May 16, 2009 at 12:08 AM, Maurice Hilarius wrote: > SandeepKsinha wrote: > > .. > > RAID 4 vs RAID 5 > Actually debatable. They have their own pros and cons and especially > where you don't consider the physical properties of disk. > Addition of new disk, differences in speed of disks, etc.. create > bottlenecks especially in case of RAID5. > > Except hot spot issue with RAID 4, I find it better than all others. > Also, most of the proprietary solutions from IBM, Adaptec and NetApp > suggest RAID4 as compared to others. > > No offenses please, this is just an opinion. > > > In a lot of=A0 uses, RAID4 is actually preferable. > Putting all parity data on one disk allows us to "cheat" and use a fa= ster > drive for that parity disk. > Thus we can gain some performance over RAID5 or 6. > > To avoid the risk factor increase, we can use a more reliable AND fas= ter > disk/interface for that parity device. > > For reads we gain a fair bit of performance by doing this. > > Further, we may "cheat" by using a single larger parity disk. > By doing so, if we add more data disks, we still have reserve space f= or > growth on the larger parity disk. > > Yes, our write rates are lousy, but for some uses this is OK. > Yes, rebuilds are slow too.. > What makes you think that the rebuilds are slower? > > > -- > With our best regards, > > Maurice W. Hilarius=A0=A0=A0=A0=A0=A0=A0=A0 Telephone: 01-780-456-977= 1 > Hard Data Ltd.=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 FAX:=A0=A0= =A0=A0=A0=A0=A0=A0=A0 01-780-456-9772 > 11060 - 166 Avenue=A0=A0=A0=A0=A0=A0=A0=A0 email:maurice@harddata.com > Edmonton, AB, Canada =A0=A0=A0=A0 T5X 1Y3 --=20 Regards, Sandeep. =09 =93To learn is to change. Education is a process that changes the learn= er.=94 -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html