Re: SCSI Channel to LTO drive rule of thumb
Where comes this divide by two rule from? Is this something related only to 3590 drives? For SCSI this cannot be true because there would be no way to have 5-6 disks on a bus with this rate divide. Zlatko Krastev IT Consultant Cook, Dwight E (SAIC) [EMAIL PROTECTED] on 20.12.2001 17:55:54 Please respond to ADSM: Dist Stor Manager [EMAIL PROTECTED] To: [EMAIL PROTECTED] cc: Subject:Re: SCSI Channel to LTO drive rule of thumb Well, I can fill you in on 3590 drives and that might be close to LTO's for each drive on the chain, add half of the previous drives thruput with 3590-B1A's a single drive on a scsi card all by itself is rated at 9 MB/sec add another one on the chain, you will gain another 4.5 MB/sec (9/2) or a total of 13.5 MB/sec add another one on the chain, you will gain another 2.25 MB/sec (4.5/2) or a total of 15.75 MB/sec add another one on the chain, you will gain another 1.125 MB/sec (2.25/2) or a total of 16.875 MB/sec so you see, past two drives on a card, things get ugly fast... -Original Message- From: Taylor, David [mailto:[EMAIL PROTECTED]] Sent: Thursday, December 20, 2001 9:21 AM To: [EMAIL PROTECTED] Subject: SCSI Channel to LTO drive rule of thumb Hi *, Can anyone share with me, a good rule-of-thumb for the maximum number of LTO drives that should be attached to a single Ultra-II SCSI bus? Using the theoretical max transfer rates of 15 MB/s for the drives and 80 MB/s for the SCSI, I shoould be able to put 5 drives on one bus and still have room to spare (theoretically).What is the generally accepted maximum number, in the real world? TIA David Taylor ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com **
Re: SCSI Channel to LTO drive rule of thumb
Hi The maximum would be 2 drives. But I'd suggest only one drive per bus. best Regards Daniel Sparrman --- Daniel Sparrman Exist i Stockholm AB Bergkällavägen 31D 192 79 SOLLENTUNA Växel: 08 - 754 98 00 Mobil: 070 - 399 27 51 Taylor, David To: [EMAIL PROTECTED] DTaylor@WBMIcc: .COMSubject: SCSI Channel to LTO drive rule Sent by: of thumb ADSM: Dist Stor Manager [EMAIL PROTECTED] RIST.EDU 2001-12-20 16:20 Please respond to ADSM: Dist Stor Manager Hi *, Can anyone share with me, a good rule-of-thumb for the maximum number of LTO drives that should be attached to a single Ultra-II SCSI bus? Using the theoretical max transfer rates of 15 MB/s for the drives and 80 MB/s for the SCSI, I shoould be able to put 5 drives on one bus and still have room to spare (theoretically).What is the generally accepted maximum number, in the real world? TIA David Taylor ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com **
Re: SCSI Channel to LTO drive rule of thumb
Well, I can fill you in on 3590 drives and that might be close to LTO's for each drive on the chain, add half of the previous drives thruput with 3590-B1A's a single drive on a scsi card all by itself is rated at 9 MB/sec add another one on the chain, you will gain another 4.5 MB/sec (9/2) or a total of 13.5 MB/sec add another one on the chain, you will gain another 2.25 MB/sec (4.5/2) or a total of 15.75 MB/sec add another one on the chain, you will gain another 1.125 MB/sec (2.25/2) or a total of 16.875 MB/sec so you see, past two drives on a card, things get ugly fast... -Original Message- From: Taylor, David [mailto:[EMAIL PROTECTED]] Sent: Thursday, December 20, 2001 9:21 AM To: [EMAIL PROTECTED] Subject: SCSI Channel to LTO drive rule of thumb Hi *, Can anyone share with me, a good rule-of-thumb for the maximum number of LTO drives that should be attached to a single Ultra-II SCSI bus? Using the theoretical max transfer rates of 15 MB/s for the drives and 80 MB/s for the SCSI, I shoould be able to put 5 drives on one bus and still have room to spare (theoretically).What is the generally accepted maximum number, in the real world? TIA David Taylor ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com **
Re: SCSI Channel to LTO drive rule of thumb
Don't forget to factor in drive compression. I have seen 4 to 1, which requires 60 MB/sec bandwidth to keep the LTO drive streaming. (If an LTO doesn't stream, figure 1.5 to 6 MB/sec before compression, depending on file size) Orville L. Lantto Datatrend Technologies, Inc. 121 Cheshire Lane #700 Minnetonka, MN 55305 Email: [EMAIL PROTECTED] V: 952-931-1203 F: 952-931-1293 C: 612-770-9166 Taylor, David [EMAIL PROTECTED] Sent by: ADSM: Dist Stor Manager [EMAIL PROTECTED] 12/20/01 09:20 AM Please respond to ADSM: Dist Stor Manager To: [EMAIL PROTECTED] cc: Subject:SCSI Channel to LTO drive rule of thumb Hi *, Can anyone share with me, a good rule-of-thumb for the maximum number of LTO drives that should be attached to a single Ultra-II SCSI bus? Using the theoretical max transfer rates of 15 MB/s for the drives and 80 MB/s for the SCSI, I shoould be able to put 5 drives on one bus and still have room to spare (theoretically).What is the generally accepted maximum number, in the real world? TIA David Taylor ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com **
Re: SCSI Channel to LTO drive rule of thumb
Actual observed transfer rate here is 15 MB/sec per drive, two drives on the same card. These are feature code 6205 dual SCSI-II cards in an IBM S7A, with just one port in use. I feel I'm being limited by the SCSI cards, because this application is showing a 3:1 compression ratio on tape and should be seeing something along the lines of 35 to 45 MB/sec if IBM's write-up on the LTO can be believed. (I get between 245 and 342 MB of data on the 95 GB LTO tape). I hope to get some additional 12 meter cables after the first of the year and see if I can get better performance by using both ports on the card. OTOH, I may be running into internal limitations on the PCI bus from the S7A -- the cards are in slots listed in the PCI Adapter Placement reference, but in the seventh and beyond listed slots (the more preferred slots having fiber channel and gigabit ethernet cards). Depending on the system you're driving the tapes from, you may hit a bottleneck at the system bus level before you hit the SCSI-II bottleneck. Tom Kauffman NIBCO, Inc -Original Message- From: Cook, Dwight E (SAIC) [mailto:[EMAIL PROTECTED]] Sent: Thursday, December 20, 2001 10:56 AM To: [EMAIL PROTECTED] Subject: Re: SCSI Channel to LTO drive rule of thumb Well, I can fill you in on 3590 drives and that might be close to LTO's for each drive on the chain, add half of the previous drives thruput with 3590-B1A's a single drive on a scsi card all by itself is rated at 9 MB/sec add another one on the chain, you will gain another 4.5 MB/sec (9/2) or a total of 13.5 MB/sec add another one on the chain, you will gain another 2.25 MB/sec (4.5/2) or a total of 15.75 MB/sec add another one on the chain, you will gain another 1.125 MB/sec (2.25/2) or a total of 16.875 MB/sec so you see, past two drives on a card, things get ugly fast... -Original Message- From: Taylor, David [mailto:[EMAIL PROTECTED]] Sent: Thursday, December 20, 2001 9:21 AM To: [EMAIL PROTECTED] Subject: SCSI Channel to LTO drive rule of thumb Hi *, Can anyone share with me, a good rule-of-thumb for the maximum number of LTO drives that should be attached to a single Ultra-II SCSI bus? Using the theoretical max transfer rates of 15 MB/s for the drives and 80 MB/s for the SCSI, I shoould be able to put 5 drives on one bus and still have room to spare (theoretically).What is the generally accepted maximum number, in the real world? TIA David Taylor ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com **
Re: SCSI Channel to LTO drive rule of thumb
This is documented in the 3584 UltraScalable Tape Library Planning and Operator Guide, table 28. Drives with No Compression: LTO Ultrium Ultra2 SCSI4 LTO Ultrium Ultra SCSI 2 Drives with 2:1 Compression: LTO Ultrium Ultra2 SCSI2 LTO Ultrium Ultra SCSI 1 __ William Mansfield Senior Consultant Solution Technology, Inc Taylor, David To: [EMAIL PROTECTED] DTaylor@WBMI. cc: COM Subject: SCSI Channel to LTO drive rule of thumb Sent by: ADSM: Dist Stor Manager [EMAIL PROTECTED] IST.EDU 12/20/2001 09:20 AM Please respond to ADSM: Dist Stor Manager Hi *, Can anyone share with me, a good rule-of-thumb for the maximum number of LTO drives that should be attached to a single Ultra-II SCSI bus? Using the theoretical max transfer rates of 15 MB/s for the drives and 80 MB/s for the SCSI, I shoould be able to put 5 drives on one bus and still have room to spare (theoretically).What is the generally accepted maximum number, in the real world? TIA David Taylor ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com **
